RACES

 

Radio Amateurs Civil Emergenies

To,

GSDMA throgh district collectors office.

Veraval

Thank you for inviting me for providing citizens input as Ham radio operators.

My name is indrajit. I am one of the oldest Radio ham based at the Junagadh. My identification call sign is VU3INJ . VU stand for india, 2/3/22/33 etc grade nuber, INJ is 2-3-word alphabet. This call sign recognized world over and points to me only.

We have very few radio amateurs in old junagadh district and lesser in Gir-Somanth district. Hams are concentrated around Rajkot, Bhavnagar, Surat, Baroda, Amdavad, Gandhinagar, Mumbai etc

Junagadh, Gir somanath, Porbunder [ all old Junagadh district ], Bhavanagar, Jamanagar has long sea shore lines thus prone to natural calamities. One of the serious threat is Tsunami. Thus i seize this opprtunity to apraise few thoughts regarding usefulness of radio.

Ham radio is primarily used for self learning the electronics & communicatins, radio engineering, making own stuff and self communication as non profit hobby.

Historically in the early days around 1900 the long wave used with simple instruments for ship to shore morse code message. See titanic movie & famous SOS message. There was no rules regulations except non-interference to commercial service & interest of state. There were already transatlantic cables for communications usages. The USA was leading in making technology rules world overs under International Telegraph & Telecome Unions. American Hams were allotted short waves. Their experimentation leading to many technology innovations, commercial interest grew thus world over only few bands of frequncies on non-interference primary basis was given to ham radio related comunications. India honors it. ARRL is their leading body.

In india, Central govt allotts the licenses to all, be it govt agencies, commercial or citizens under Indian Telegraph Act etc . license is a must to use any radio equippment for any communcation. Only central govt has jurisdiction over this matter. State agencies are exluded in this matters.

Radio Hams helped in first, second WW for providing self trained engineer expertize. In natural calamities radio hams volunteers to civilian aid. We expect that in the time of natural calamities the radio hams will come with their fancie equipments and help local govt agencies. It is not so simple, the states govt secretariat HQ gives autharizations and relaxes rules for hams to operate in field for certain time period everything is tolerated as long as useful to society.

In india the usage of citizen band and ham radio usage is there but not higlighted.

Is there a way out lets explore ;--

We citizens in good times have easy communications due to mobile fone network, BSNL fibre optics. The govt have , the police wireless network of HF & VHF, RRTY & many digital modes, Forest has VHF network, customs, port authorities, air port, cost guards with own dedicated HF network. Railways have its own servers, firbre network under CRIS delhi,& telefone,VHF. Powerline suplliers has their own point to point. But, all these are not accessible to even state's other agencies nor states general administrations. Gujarat state has state wide area network. GSWAN. All are bell and whiste, when calmities comes nothing works for citizens.

All these comunication platfoms have their dedicated users but not tailoured for the emergencies as they can not be deployed within short time in the fields. Satelite fones can also replace land based comunications platforms but its costly in equipment, use and number of devices needed will be large. Not easy solution for releif work.

Then why depend on Amateurs ?

Ham radio can be deployed into field within short time with enough manpower with minimum of cost and can provide point to point, state/dist HQ to field & within local areas. Long range and short range, low power to high power stations. VHF HF all mode. Beside ham radio systems do not require testing time as they are always in use.

How to use Ham radio in disaster management, Tsunami situatoins ?

Its a valid question, for that we need licensed ham radio operators and their eqipments with temporary moratorium in license operating restrictions.

Where we can find hams ?

First easiest is search them https://www.qrz.com/db/VU3INJ

second is hamfest directory, call boooks which list all past present HAMS with their postal address. Many hams have their social media groups of their CLUB stations.

Third, In gujarat state we have biggest elite working club GIAR, Gandhinagar with its own web site. Most of them are state secretariates babus and other well todo good hearted peoples. doing examinations, expeditions, making new hams .They are instrumental in many good work. https://giar.org/

Fourth in-house. If GSDMA dont find local hams then make/ create new hams from their own staff. Investing in them will help increase the network reachability, instant access to dedicated human technical assets which makes situations easy.

What is the disaster management need & how ham radio can fit in.

In my humble imagination it will be, primary chanel is not/working but you want backup chanel or your intented area is not covered by primary regular communication system when it failed due to emergencies , then

State HQ/Gandhinagar wants to relay a message information,

with HF equipment relayed message come to districts and/or clubstation or

to local ham radio statation in nearby area,

which further gives that to concerned ones.

In the field where we are doing relief & rescue work we need to communicate, there low power hand-held VHF walkey-talkey comes into handi work, seemleesly talking with each other in local language in real time with all human emotions. Voice is an excellent mode here.

Anyone having ham radio equipment & licenses can use it. In radio hams presence other civilion can use radio. Generally VHF radio works 5km to 50km depending on antenna radio power mode etc Now a days radio VHF equipment are manufactured in india and comes cheap in bulk buy.

What is the problem

All communications, equipments, frequncies, usage highly regulated by central govt. Even local state bodies are not excempt from it. Hower noble cause, you can not break law. We need radio amateurs, if we can't find , then we should create them.

How to create hams & use them for disaster mangement use.

Yes, we do have glaring example in south india, there NIAR national institution of amateur radio made club stations, gave coaching training for examination of ham radio licenses. Facilitated for examination to be taken by Wireless Planning & Coordination Wing, govt. NIAR with state and central govts equipment-funds/grants deployed many HF VHF radio stations for volunteer work. http://www.niar.org/

first we can impliment same model with help of our own GIAR. This way you can fetch volunteers from general public, provide equipments from govt funds.

Second way is fetching from govt serving individuals. In district administrations there are many educated qualified peoples in various technical / normal posts. Say police 'wireless' service, Science teachers, Science college professors, polytechnic teaching staff ,department of post & telegraph, there willing volunteers can be found and requested to render services as ham. retd staff will also work fine.

Third way, Science and engineering students can be also motivated to give examination and get ham licenses. And if institutes can install club stations then it will be a big solutions.

Forth way, creating in-house in disaster management communcation centre. the GDMA staff volunteers can be motivated to give exam and use govt funded radios and establishing ham radio club within GSDMA premises as done is USA. ARRL, american radio relay league also do RACES radio amateurs civil emergencie https://www.arrl.org/

In india who gives lienses ?

WPC wing, Ministry of Communications Department of Telecommunications Sanchar Bhawan, 20 Ashoka Road New Delhi- 110001

here is https://saralsanchar.gov.in/wpc_usermanual_list_for_home.php read ASOC

The WPC is the National Radio Regulatory Authority in India and manages the country's frequency spectrum for all wireless users, including amateur radio enthusiasts.

The WPC conducts the Amateur Station Operator's Certificate (ASOC) Examination, which is mandatory for obtaining an amateur radio license. There are many types of licenses, Restricted Grade [VHF telephony only] Grade II, Grade I, Advanced Grade I with various different frequencies mode power usage differences.

State-region has its own Radio Monitoring Station, forbidden for any inquiry visit or tresspass, they monitor everything. The organization is responsible for monitoring the airwaves to ensure compliance with regulations. They take exames and gives result to regional HQ which gives it to Delhi .After an applicant passes the examination and meets all other security requirements, the WPC issues the license and allots a unique call sign.

To become a licensed ham radio operator in India, an applicant must Be an Indian citizen and at least 12 years of age. The examination tests knowledge of basic radio theory, regulations, and Morse code proficiency for certain license grades are required which needs training. [very important for success in examination] License fees are nominal & low. Only equipments cost high.

Apply through the Saral Sanchar portal--

as per Office Memorandum No. P-14036/03/2023- COP, dated 28 February 2025 all applications for amateur radio licenses must be submitted online through the Saral Sanchar portal of the Department of Telecommunications (DoT)

The rules for amateur radio operation in India are governed by the following .The Indian Wireless Telegraphs (Amateur Service) Rules, 1978 (and subsequent amendments)The Indian Wireless Telegraph Rules, The Indian Telegraph Act, 1885.

role of police is regarding verification during license process, this is the biggest bottleneck any citizen faces as this request is different from their regular police work.

Administration has official secrets act. IPC chapter VI offences against state. Generally all ham are security cleared by state and central agencies. Hams are visible, accesible, well regulated, documented. Thus nothing to fear from them. Ham radio frequencies are monitored by central govt ITU ARRL other hams world over and any untowards incident, misuse, piracy etc are always complaint made to wireless monitoring agencies of central govt. Ham radio frequencies are openly audited by listener world over.

Lets see freqience bands modes

BAND meter	Frequencies megahertz	CW, RRTY and Data modes	Voice mode
160	1.800-2.0	1.800-1.860	1.843-2.000
80	3.500-4.0	3.500-3.750	3.700-4.0
60	5.5	Not allowed in india
40	7.00-7.300	7.000-7.150	7.150-7.300
30	10.1-10.15	10.100-10.125 cw 10.125-10.150 rtty data	Not allowed in india
20	14.000-14.350	14.000-14.150	14.150-14.350
17	18.068-18.168	18.068-18.100	18.110 -18.168
15	21.000-21.450	21.000-21.200	21.200-21.450
12	24.890-24.990	24.890-24.930	24.930-24.990
10	28.0-29.7	28.000-28.300	28.300-29.700
2	144.000-146.000	digital telemetry etc	NBFM

Indian hams generally use 2 meter, 20 meter, 40 meter SSB voice & CW.

The old marine radio equipments from alang shipbreaking is nolonger available and not useful .But there are many excellent designs kits parts from china components supply are in open market. Dont make own equipment but In my humble opinion save a bit of money and import from japan/usa ie YASUE kenwood etc.

For Emergencies usage the factory built equipments are must. They are costly but useful. Hand held walkey talkey VHF/UHF in various power ratings are needed. For base station high power VHF station with big antena, directional antenna will be useful. They should be easy to use , low weight, water proof, easy to repair.

Ham radio is for ham only. Unfortunately disaster management authority can not get seperate frequiency in it, but in Citizens Band of 26.957 to 27.275 mhz any citizen can use it with some restriction. For Citizen Band no licensing required only factory built equipment with fixed power mode frequencies. State govt GSDMA may think over this citizenband. Going for citizen band will be also viable option for day to day radio use instead of ham radio.

For field usage some sort of battery, generator, solarpanel, chargers etc needed. Some packing bags water tight containers for communication equipment storage needed. Various types of antenna for VHF and HF needed. Some measuring instruments, small repairing instruments which can be carried needed. When camping in wild, there hygine, water, food suplly, tents etc needed. All this are practical things, once we make few mock drills then can know better. Refine the parameters and devise a checklist of all things.

My advise after many years of hamming is that we needs to constantly be prepared and do preparation consistantly, so when times comes we do what we are supposed to do -Aid /rescue/ save stranded injured citizens without harming ourselves. Hams are untrained volunteers compared to dedicated emergncies staff. My sincere request, invite HAMs to GSDMA offices, make list of volunteers, what equipment they have, what type of work assistance render and make club station there. If they come, trained well then they will be useful.

In preparing this keynote i have avoided all technical words, details and tried to make sense in few words, thus lots of things associated which are glorified with hams-tales are omitted at this stage. And focused only around how its useful to tsunami rescue and how to become ham to be useful there.

Ham radio is a fascinating very very expensive hobby thus it has bloomed around those people who are willing to work hard or spend money resorces without any pecunary gain. But, togather we can grow and reach out to society at large.

Date 6 october 2025

Junagadh/Veraval

20 meter cw transmitter reviving.

 I have one small around 2watt CW transmitter based on VU2ATN AND RM96 stages. It has one 80 meter VFO which feeds to quardrupler stage from it goes around to the tx stage and then driving the IRF510 LINEAR. those were my earlier days and i did not know nothing about the IRF510 and linear at all. But it heated the 2 watt 50ohm dummy load easily so left it as it was with hope that one fine day i will revive and make it air worthy.

There is one DC receiver strip lying around. My friend VU3INK now VU2JXL is avid cw lover and infact he has made one telegram group for CW only. it is time that i put this TX on air. Plan is to dismantle final IRF stage and put one stage which can bring me around 10 watts CW with 24 volts DC input.  i think it is doable. I also have 14.0 Mhz crystal . this will put me into 14.015 range these peoples are going around. Hope it works out.

Meanwhile enjoy the pictures, everything is hand made. first compartment is a VFO a very stable one. second contains TX cahins, quardrupler, then buffer amplifier, then another tuned amplifier then IRF510 in its rudimentary form. it works.

i doublt will i make a fresh new ones or i make this tx into another one ? will require lots of change. Still not decided what i will be using for the receivers ? POLIAKOV topology my favourite or the modules i have. Because the time is short and i need to make it fast.

the box. i have hand painted it. more thena decade old.

inside the black box. each stage has its own shields as they were talking to each others and putting out the self oscilaations.

VFO and tx chain.

another view.

ENJOY, as it is. wheel has not turned up !!!

SOTA 2021 GIRNAR

 GIRNAR

I recently went to Mount girnar for the event SOTA  I have a good vedio materials and experience to share. But due to the suddent events of the life i could not put that wrtieup in Feb itself an/

it all started with this campaign. That my nearby hams were going to the HILL TOPS  and i should also join them, but that was conficting as i was not travelling due to physical debilities and no-vehicle at that remove place. i thought i also climb the mount girnar. I took my VHF/UHF baofeng handy and made a tour to my nearest hill top MOUNT GIRNAR. To had a sked plan on 145.500 to talk to them.

This journey had dual purpose. to propiate to my devi a very excellent shakti pitham.as had not visited her since 2011. a 10 years time , i was living in that city. Anyway it was now due. i make a sankalp despite my ill healthy to climb and have darshan and possibly talk. But primary target was climbing up for religious reasons.

have look at the fotographs and vedios. (to be uploaded later on)

QSK once again how to make qsk ?

     QSK

Once again i am making the QSK for the earlier made qrp  7.159 mhz vxo controlled cw transceiver. It had only simple switching and was good enough for doing tuing tuing carriers tones. but for the effective cw use you need FULL BREAK-IN QSK. 

I have found the problem why it did not work on air ? faulty dipole antenna coaxial wire. It had aluminium foil which does nto work , i should have used the copper one. dump it and will make a long wire or half-wave from that dipole install and remove the wire. let's see.

how i checked the dipole ? with the 40 meter receiver it was producing more noice then signal and with even a small house antenaa wire it produced less signal and ok volume. so that coaxial has been aproblem. sometimes it takes lots of time to find the true problem.

this time i will brew a linear for 80/40 also so that i can use the 3.686 kc system as well as 7.159 system. you need atleast 15 watts. and the 50 watts are good thing. the single FET IRF840 can produce it easily with 28 volt power supply.

before the linear is made atleast i should have the trx fully ready so this qsk. 

THE CKT.

here is the circuit. its actuall and revised from the earlier version as i changed the components.

QSK revised

The components are placed on the veroboard. I like to use veroboard for this part as it is DC control section and veroboard holes provides easy to put components. Here we are taking the two output one is with delayed on/off control of the  relay. the delay is important. Two diodes are used to clamp the capacitor discharge voltage to a set minimum. It helps quick switching off the relay.
 

component placement !! work in progress

it will be finished and then uploaded the result.  

to be continued.....

how to make pcb

 HOW TO MAKE PCB BY HAND.

pcb making by hand

 
This is a very very crude and old technique. it is wonderful for prototyping the small RF projects. This is a unique in a sense there is no through hole. the component is surface mounted but use normal components. It has maximum copper. It is more rigid and solid then sticking the copper-pads on the copper plain. Here component are also not hanging loose over the copper pad. the computer generated pcb are more efficient, accurate & repeatability. But, hand made pcb are designer, small kit builder, new hobbyist friendly. 

I have seen that these hand made PCB works wonderfully for the RF devices. I use it exlusively.

We need good copper clad boards. Better start with single sided glass epoxy based board. That is mechanically strong, copper is little thicker then the normal ply based copper board.
I use oil-paint to paint the tracks. My recommendation is to use two colors one for tracks, pads etc and one for plain copper ground. That way we do not mix-up while painting. 

First draw the ckt on plain paper. correct it for all mistakes. put the circuits in small small portions/modules. That will help finding the faults or isolating the RF stages.
Then have actual transistors, resitors, inductors, capacitor, connectors etc you want to use for their dimentions.

Once again see how this components will be placed on board, what will be their size, orientations, shieldings etc. Signal flow directions. Vcc lines. Controls, indicators etc.
Oscillators always need to be shielded even if it is xtal controlled.  xtal filters needs more ground plane. 

Be it RF amp or AF amp using a single transistors you need atleast minimum3-5 pads for placing components around transistors. IC needs atleast whatever its pin counts, so on and on.
After placing components with minimum distance & not crowding them you can create the copper islands on papers. check it with components size. See your whole project in simple modules say input RF band pass filter, Rf amplifier, filter, diode detector, xtal oscillator, Af amplifiers, IC amplifier , power supply, connectors. Thus ckt are understood as a modules unit. then giving transistor ic parts number makes easy for us to loacte them in PCB & ckt and for future discussions. Thats it !!! we compartmentalized our pcb into module after module. When you are placing the components see your circuit diagram. refer to it. check you are not missing any components. Visualize it. Thus finally on paper your board is visualized and drawn. use 1 inch graph paper that will increase accuracy.

Now take the pcb. measure it cut according to the size you realized on paper. wash it, clean for dirt thumb prints, greece etc. file the edges clean smooth it.

Generally i use 3 inch by 5 inch size boards. Not hard and fast but this size is ok. On this draw one inch greed lines. These boards are not small nor big. Enough for a small project. 

Sometimes we have to cut the board according to our box or the project in which we already want to add & fit into. there we can use 3-4 small sized boards and put them on vertical stack. usable. imagine. when you use the sealed can/ shieldings then signals do not see others and do not interfere. That's good enough. Sometimes  for shielding put 1-2 cm high copper board that also works good. 

When designing see that you have maximum copper ground area. It should not be broken between two module that  create complications & earth loop. You have connectors at edges, there is round holes for the pcb. if these holes needs to be isolated then plan it early. 

Before etching do not drill holes. That part do not cover with color and it will etch-out and drill hole. So that nut-bold/screw used for that hole will not touch our pcb ground.

After pcb is drawn checked i let is sleep for 12 hours/ over night. Next day i check for any mistakes or things i remember to put at hindsight. 

If there is any variations, just rub the boards with ink-erasur/ alcohol that part of whole pcb board and wash with water dry and do once again with pencil & markers.
Use ruler for straight lines. go slow do not make mistake. Now foto graph that for future reference.

pcb coloring/painting is simple. use the finest knibbed edge / paint brush. dip and brush fir island, tracks. let it be straight lines boxes do not let it blot & spread out etc.
let is dry. 

Then use the different colour paint and paint the copper ground that you do not want to etch. At this time, mistakes are done/happens as colours touches already painted tracks. so be careful. if you make mistake, note it down on paper and move on. when the colour dry at that time remove that colour with small kife very carefully. 

So, the board will start drying within a hour but do not touch it. let it dry over-night. next day these board is ready.
If oil stains your hand wash it with soap.
 

 

Next day when the board is dry see that it is clearly dry paint is not soggy. if need arise let it dry for another day. After then put that pcb into fecl3 ferric clride solution/ or HCl hydro-cloric acide and add h2o2 hydrogen paroxide ( available from medical store) and about half hour one hours it will etch. time to time stirr it. is it bubling or not, then add more h2o2 and it will start bubbling. When the pcb is etched take it out and see are you able to see track from back side. then its done.

wash your pcb with simple water, soap. have little bit of scratch-papers, i use from kitchen. and remove oil paints. Do a visual check. have continuity check with mutlimeter, if needed  cut the track with knife. Now you can not put pcb into etching solutions.

here is the vedio of painting the pcb full 12 minutes process. click here.

https://www.youtube.com/watch?v=61WyLP8NHds

After this you should wrap etched copper pcb in dry cloth or paper till you use it.

For tools i used, marker pen, knife, ruler, paint brush, paper drawings. 

to be continued... etching fotos and end result. 

RESULT

the pcb was etched successfully. here is the part2 vedio of pcb making. it looks nice.

https://www.youtube.com/watch?v=T7KEtFLjVts 

use fresh acid, fresh hydrogen peroxide. add the hydrogen peroxide generously and it will bubble up. wait wait  then it will etch fast. never used the acid used earlier. do not use more acid then dippin the pcb. keep the tray as small as possible, more acid more hydrogen peroxide needed. so use small container that dips the pcb and thats it.

always keep water and cloth to wash acid if it touches your body. use the goggles , white glass for eye protections.

(by the way i have populated the board and DC receiver based on poliyakov design is ready here see the fotograph and write up will be here and vedio will be here :- link to be included later on )

3686kc  poliyakov receiver.

the wheel is successfully invented use it.

JH8SST/7 FT8 dc receiver

JH8SST/7 FT8 dc receiver

In one social media one of my friend, living in JAPAN call sign  JH8SST/7 does lots of home brewing. I liked his design skills. His boards are cute, simple & working.  I saw & followed his design steps as he outlined on the twitter and asked one or two questions and he very courteously replied it. I am putting his work for my information and as a collected resource for inspirations for others. I hope my friend JH8SST will like this write-up. All copy right and credit is due to him. I just publish as it is.

Assembling a direct conversion receiver for 3.5MHz FT8 reception.  

The circuit diagram

First of all the circuit diagram. this ckt is based on VK3YE our all time favorite PETER from Australia.

JH8SST/7 DC receiver circuit

Now, i have a look at the pcb design and the text with them as translated from japanese to english by google translators. I will request JH8SST to look over this pages for any correction etc.

3.531 mhz xtal

design

PCB pattern

pcb pattern etched & ready

DC rx and other 28 Mhz SSB rx board etched togather

Hi patterned boards, do you want ferrocloride bath ?

xtal osc stage ready

Ahha finally completed board !!!

See 9v pp3 battery & board in plastic box.

with antenna tuner board is roaring.

another look of the board please.

Computer FT8 screen dump

beautiful japanese balcony with antennas.

QSL CARD.

JS8 & FT8 are slightly different thing. At present i know nothing about the JS8Call but have a look at its American inventor vedio https://youtu.be/G2kv41mVLPk    a 15 minutes vedio.Hope that will give enough information's about what is JS8Call , how to install software into computer, what should be interface between computer and transceivers and also do not forget to see the video of vk3ye channel. http://js8call.com/

Now the text as translated, you can understand  it as a build log.

1- Inspired by VK3YE's 3 Transistor's only FT8 Direct Conversion receiver, I designed and built the 3.5 MHz FT8 DC receiver. An RF stage was added to make it as RF-Ring Detector-AF, 1-V-1 configuration. I wonder if this simple receiver works for FT8 reception ? 

 

2- The Home Brewing in my winter vacation. I've completed all of the PCB's  as i planned. The 3.5MHz FT8 receiver has been tested and confirmed to work with no problem. It took a bit longer time to complete all of those PCB's. 

 

3- On the first and the second day in my winter vacation, I completed PCB etching. Unfortunately, the parts I ordered for those PCB's were not delivered during the vacation, but I managed to assemble them by using parts I have. The assembling procedure was started from the 4.630MHz Crystal Converter board, and then, 3.5MHz FT8 receiver board. 

 

4-  I ordered the 3.531MHz HC49 / U crystal for the FT8 DC receiver to the Arrow Electric with express surcharge. First, I assemble the crystal oscillator circuit portion and tested. It oscillated with no problem and the frequency was adjusted to 3.5310MHz by a TC/trimmer capacitor. 

 

5- The diode ring detector portion was assembled. 

 

6- The RF transformers were wound on the 10K coil-form, 2SK241 RF FET and related parts were soldered, and the RF stage was completed. The FT8 receiver board was completed. I wonder if this kind of simple receiver really works for FT8 reception ?

 

7- The Audio frequency amplifier portion was assembled. 

 

8-  Completed & put into Akizuki Electronic's plastic case. Does this simple DC receiver really work for receiving FT8 signals ? 

 

9- Testing, the 3.5MHz FT8 receiver. At around 20:00, many signals appeared on the waterfall. The signals from JA1, 2, 3, 6, 9, 0 areas were decoded. The antenna is a only 5m lenths wire + simple coupler. I was excited. 

 

10- My "Mini shack", comprising of Home made 3.5MHz CW receiver for practicing Japanese Characters CW reception and the very simple, RF-Detector-AF amplifier configuration 3.531 MHz FT8 DC receiver. The antenna of the 5m length wire + coupler is too simple, but by using those receivers, now I can enjoy the SWL/shortwave listening of FT8 in addition to the reception and practice of Japanese character CW .

 

--- xxx ---

My note  

Now, i feel that FT8 reception will be achieved by a simple device and that will be inspirational for other to make their own. IMHO The Japanese transistors can  be substituted by any of our locale HF variety or even BC547 will work as used by VK3YE, 2N3819 FET, 1n4148 can be substituted for build. Will i ever try it ? do not know. I need to finish-up my long pending projects, box them up and then think on these digital technology.  

My dear friend JUN did look into the blog and corrected the google's Japanese to English translations. I am thankful for that. Now everything is OK enjoy the wheel.

PCB modules sketch

 This are my standard design for pcb making by hand.

In early days i made the pcb with a very crude way, painting the pcb copper side with oil paint. they dry it and then etch it , wash it then put holes. And polish it. Then populating it. 

It enhanced my RF circuits functions due to copper plains giving a good ground. Earlier i used to make circuits on general purpose 20x30 veroboards. They were good but due to the holes it very not useful in high frequency use. But, there are some uses which it is better to use vero-boards. 

In the plain copper PCB board the substrate are two types. Use epoxy-glass based one, Those are strong mechanically and electrically.

Here are my standard sketch

in first page you can see xtal oscillator , xtal filter, poliyakov diode detectors, RF amp stage with xtals used as IF or TRF . so this is a complete receiver.

 

In second page a simple RF or AF amplifier, common emitter format. that is also a standard building block.

one day i will build this into one and that will be the end of R&D in poliakov receiver. That will be available to all.

DDS VFO CONUNDRUM 2020

DDS VFO this little useful nasty things has always intrigued me from the start. My tick-toe started when i first met dear friend VU2UPX he gave me a pcb & IC to populate to make dds vfo. I procued the at that time famours AD9851 CHINESE module from banglor priya sloka arya ji. He was a very good gentle-men. he gifted the arduino nano. At that time tried to make one DDS VFO BUT could not due to the software skill-set was not enough. My friend from the EU helped me in my medical as well DDS VFO. He made a shield for me. I tried to test but somehow could not make it. As at that time My computer was old and i did not know how to programe ARDUINO etc. 

Time passed on. one fine day our beloved VU2DEV-SK also gave me a DDS VFO. even sasi bhusan of indian homebrewers forum gave a pcb but what i lacked was the ATMEGA328P a programmed IC but no one gave that to me that programmed. So, with time it went to dust.

Then few days back i saw on facebook one of my friend SHUDHINDRA  of banglore providing the VFO based on si5351. i liked his short introductory vedio. I needed something which is not power guzzling. gurudevs VFO was boxed well but it required 12v 1Amp power source of its own and did not understand its functions. ordered teh VFO. i chatted with him on whats-up. oHH now i have two working fones. hee hee. Then deposited money & he sent me via INDIA POST. it arrived. 

You can see its un-boxing vedio click here. I should appreciate his working skills are very good, nice packaging, boards are sweet may be specially custom made. I do not know from where this VFO+BFO is used. but anyway it is useful one. 

After unboxing it i tested it for VFO sections. I had made a superhet receiver board with 10 Mhz IF. it utilized teh xtals. i could not get on air signals with it there is some loss or gain mismatch. hard to probe it. I used it for testing the transmitters signals. I connected that receiver and this new VFO section. i did not connect wire for 10 mhz OSC of si531. The vedio of test is here. I find the DDS VFO very stable and well marked. the display is good. hardware part nothing to tinker for we end user. he has done it carefully. 

He has done everything. Software the arduino board has usb port so you can update if you have skills or simply replace it with y our own arduino. interesting. powered on and it started pumping the RF put to the diode mixer and it received my local Tx signal on 3686kc cw tx. interesting. single side reception is possible with superhet. It use the push button within rotary encoder for changing the resolution of 1 hz, 10 hz, 100 hz, 1k hz, 10 khz, 100 khz, 1 mhz in incremental step. With rotary you can increase or decrease the freq in step. 

Everything was smooth but i am here to find the faults. lets find first fault. This push-button is with rotary encoder, so its very tiring to push and sometimes i miss it as i have not pressed hard. menu also opens up with this. So, this is  software fault. One thing i noticed that push button increase the freq STEP resolutions it does not decrease the resolution steps say from 10 khz you can goto 100 khz step but can not goto 1 khz step. This is very annoying for rapidly changing the frequency. this is software flow. i need to ask him is it intentional where this ckt is originally used may be that will be the case.  up-down switch is highly recommend.

Second thing i find very very annoying is that in this beautiful device there is no provision for the BFO RIT. receiving side we need RIT. there must be a provision for changing BFO frequency, because our homebrew rigs xtals are not perfectly aligned and that is detrimental to receiving and transmitting on same frequency. If one pot is fixed for this that will be a nice thing.

So, this are two flows and it related to the SOFTWARE. it can be changed and i also humbly suggested. May be he will come up with solutions to my questions one day. But over-all it is WORTH HAVING THIS DDS VFO.

i recommend to procure this DDS VFO from him.

 

GDO AN PRM10

GDO AN PRM10 Recently my friend gave me his AN PRM10 grid dip oscillator. Well, in days of micro SDR and softwre DDS VFO who plays with this WW2 age devices ? 

It was a nostalgia for me. Cost was a bitter stip but he made it light due to his affection for me by sending me extra 2,5 kg power transformer, 50 watt dummy load and a meter. There were other buyers but he wanted to sell to actual users. My friend inquired why i did not home-brew anything or not on air for quite some time ? we had big chit-chat about me, my lifes updowns, homebrewing etc. he lowered price for me.He is my generous benefactors over the years. Earlier he had gifted me some RF boards, SPART hard compy a years magazine set. I just grabbed this GDO. I could have bought the microBITX but now a days i am detesting everything slamic. So, i wait for the xtian & pure hindu brewers to get me things. Well, that is my spiritual issue and nothing can be said or done on that. Well will finish later on.

He posted me the device through the couriers. it took strong 10 days to reach me. Then i did a first test of power on and blew the fuse. Then i reverted to him with my problem and tried to make my transformer using the reverse transformer idea but as the loading was pure resistivity, it required the current and voltage. So, once again i requested to send the transformer (as free fund). Very kind of him. its a bit heavy 2.5 kg piece. he specially found out from some radio junk. It was very dusty. dusted it used it. 

Then did the first test. with this new power supply. it dipped only 14 Mhz coils. i was thinking that other coils are 10 Mhz which it did not dip on 10-22 Mhz range nor in 5 to 10 Mhz range. Later on i ferefered my ckt diagram. Actually the If was a tunable 4 Mhz around. so, i said that it is success. hee hee. 

Then today did a oscillation check. injected the RF oscillations into the xtal controlled DC receiver. it produced good stable tone. Freq was very stable. good enough. the stray metal capacitance was not affecting the internal device. so that was the thing if you make a gdo it should be air tight. ok later one. 

on my you-tube channel there are videos. just google AN PRM10 and my videos come up on search. There are not many of these equipment surviving. I do not know whether how it dips or not as never used this type of instruments. thus test is going on, as i have to master this equipment. 

Yes, the equipment works but i will take time to learn.

110 volt AC conundrom.

 110 volt AC conundrom.

I needed some power supply of 110 volt ac for a valve device i recently acquired. Its need was 110 volt ac 20 watt. As all valve radio devices have pure resistive  loading part . So, they require more current capacity that required in start-up etc.

Well we in india have only 220 AC line. We find lots of auto-transformers for many nintendo and other consumer product. They work for them. i can also use them. My problem is i do not want to have live wire at any part of my instrument. That is because my small kids also loiter around my shack/office room/work room and they touch and help me also. when we are testing less worry we have more we concentrate on the work. 220 ac has very small thevenine resistance that means it can source lots of current.

I once had from junk an auto transformer having 220-110-0 . i did not like because when i put my device on it that ruined my fuze. thank god. you can see that in my vedio. link is here first vedio. part 1 

and second vedios is part 2 .

Then i did thought well 110 volt is just half of our line voltage why not put two transformer back to back and get. I thought i got the solution and rushed to the shop. bought two 12-0 , 5 Amp and 12-0-12, 5 amp transformer. With mischievous smile that i conquered my problem urgently wired and the transformer. it cost me 170+170 =340 Rs approximately 5 us$. i said ok as could not get the 110 volt ac transformer. Then made it it gave me around 116 volt ac. i said ok now lets test my American soldering iron of 30 watt. If that work then sure my device with 20 watt power will work. Put my soldering iron and it loaded started to slowly heating up. i said ok, test the voltage and it was around 72 volts.

See my notes. putting here as pictures. Then, i thought that my device is not getting enough source current due to the inherent high resistance. So , i need more current to push. So, on next day i bought another 12-0 , 5 Amp transformer. paralleled it with 6 ohm combiner. Thinking was that it should see small resistance going toward the output 110 volt ac transformers and high resistance path towards other transformer. see 6+6 ohm path and zero to output transformer. 

Then i parallel 12 ohm to get 6 ohm as could not get 4.7 ohm. i think this idea is good but you need some small 1 ohm resistance that will be enough.

well what happened, first i said compare my result with only one transformer, 12 ohm. it gave me No-load 93 volt. good enough. Then with 6 ohm resistor i got 107 volts ok. but on loading 30 watt soldering iron it turned down to 43 volt ac. Why this happening because we have finite VA that wattage and we have internal resistance of the transformer so when you need more current then voltage reduces and you do not have enough umphhh. EMF.

Then i paralled two transformer. See the diagram. 

i tested and it gave 113 volt ac no load and 57 volt with 30 watt load. As last try removed the resistor by bypassing it. so it hold me around 77 volts and the iron was immediately becoming hot. which means it is getting enough current.

Despite having this 3 transformers i am not getting my result. Why why why. i did everything to reduce the thevenine resistance to get more current ?

i paused, if i had asked someone to make me a transformer then in 510/- that person might have made me a brand new transformer. what i will require is 110 volt act with 500 ma to 1 amp current capacity. it might be big. 

I knew that my thinking is right, my problem is thevenine resistance. i do nto want to use 0-18 volt ac in output transformer. As it will increase the no-load voltage and then reduce it to working one still it will be not constant 90 volt, the required minimum. What a conundrum.

What i have not tried. Looked at the setup. Not finding solutions. i gave up. solutions is simple i have more then enought VA as input. Why i am not getting the enough current and voltage as per plan.

Paused. let it go. Then in the night time when i was closing down my room then looked at other transformer. Ohh, the 12-0-12 volt ac has thinner wire compared to my other jumbo 12-0-12 5 amp transformer from different company. Ohh, it seems i found the solutions. I need to replace that big transformer with this tiny transformer.

RULE OF THUMB is that output transformer should be thicker wire then input transformer. 

Lets see.

I tried one of my old very meaty transformer having thick wire. it produced me 120 volt ac. No voltage drop. Then on loading 30 watt iron it got me around 82 volts. That means i am nearing the range of 90 volts. I am going on right directions. If i use these two big beefy with large dia-meter wire i am sure that will work out. as 20 volts loads less. and minimum voltage of 90 volts i am near about. If my shop had those tranformers i might have solutions with less cost. Anyway i will be using these power transformers also in other projects. It is not wastage.

Meanwhile, the original source, the friend who got me this GDO has promised that he has a spare power supply transformer and that will work. waiting for it.

I can say it was partial success because, theoretically i was right in getting the voltage, testing it. But, practically i invested 3 tranformers but my choice of half voltage was wrong i should have chosen 18 volt combinations, 0-18 & 18-0-18 vac with thick wire. lower voltage we go the wire gets thinner.

RULE OF THUMB  choose higher voltage transformers. Less loss in flux, hysterisis, less internal copper resistance.

RULE OF THUMB Second thing, use both transformer with thicker wire, that will reduce voltage droppings. If you are planning learn from my experience. VA ratings should be atleast 4 times of the load.

problem solved. hope this helps you out. It is possible to use this configurations for low power use. Please always avoid auto-transformers. It has shock hazard as its directly connected to the mains AC line. It can source large current so device if not fuze protected or voltage current sensitive, it will be hard to it.

so, wheel is re-invented but it has puncture. so, waiting for the spare wheel.

Third vedio of working power supply ok here is the first working https://www.youtube.com/watch?v=jLmvUZ_2dTo