Sunday, March 17, 2019

DDS VFO WTF

I had the dds vfo gifted by my ELMER OM VU2DEV, Dev garu.


At present it’s non use as I want to use it in DC RX but it’s for super het. Let’s hope to use it as it is. 

Thursday, February 7, 2019

Balun for wire antenna

making balun for wire antenna. I wanted to make EFHW.  I want to make delta loop. Wait !!! My time resources are limited.  I said what I have ? Toroid -No. but MW Ferrite road yes. Made balun.





Here is the schematics.
That might work. Hope so.

Wednesday, January 16, 2019

SLA batery charging

SLA battery charging.

I have few batery lying in the shelf. Not charged. Its sealed lead acid battery. that means its sealed. its miniversion of car vehicle batery. Generally 4 vollts are standard. So i have 500 ma - small batery, 1 amp and 2 amp batery. All just not charged , deep discharged.The previous usage experience is that i have to regularly charge it. But, could not find the commercial charger circuit.

There is very strange theories as we have used this batery system 100 years.Ohh baghdad battery ? Anyway i will be makinhg a simple charger circuit and one is fully charged then will constantly tripple charge it.
For amazement look at the battery which might have used for GOLD-electoplating the Egyptian idols and possible to light up lamps.
baghdad batery

baghdad batery


Have a look at the baghdad battery.





















And i opened my SLA batery.

Need to get the distilled water and a syringe to fill it up. You have to reverse connect it. Then fast charge it. Trickle charge it. And use it and recharge it.

2. Cover opened
1.SLA batery

3. Bottle opened
I have to buy the distilled water or use the rain water. yes, i have plenty of rain water. i collect it during rainy season and keep it in bottle for a year long use to worhip my gods idols.  Water tastes good.

Sunday, January 13, 2019

Silent key

every radio station when closing down calls for last message anyone waiting any last message. Station vu3inj calls for this.  From now on everything should be taken as  SK.
Life is beautifully ful 

Sunday, January 6, 2019

7159kc trx qsk

I had a rough time understanding and choosing a proper qsk for my TX and receivers. If you see my early post you will see that I used different modules to make Transmitter and Receiver

In this transceiver i tried to implement TX and RX chain in a single BOX. My results are very satisfactory. So, lets hear the success story of QSK.

By the way For this TRX Next step is to make a cw band xtal VXO of 7000kc (This xtals were given by my friend Arya ) , and 7159kc DSB TX.  Need of VXO is apparent. A single stage af filter is also good. But let me first put it on air with just 10 foot high about 50 feet long wire. It works. Years of homebrewing has told me to make a solid brew. Put your modules firmly , in  a box, shield them. use decoupling , use plenty of space. Make modules and make it in small steps. Test it and see that it works.
Filter 40 meter

Qsk

Filter


Yes wheel is reinvented and revised.
I have put the few fotographs here and will write more about it.

1. You need a Relay DPDT (8 pin relay) , a must to change over the Antenna and Generate control Vcc  ie. RxV, TxV.

2. Transistors can be used to switch few modules. (will describe later on). For SSB single relay will work but for CW you need more control mechanism. Or use a relay and manually switch TX RX on off, clumsy.

3. You also need Diode 1N4148 switching for protecting the front end of RF Amplifiers. I implimented the M0DGQ as given in the SPRAT magazine. picture given below. Here if there is no control voltage switch protects our front end. This switching always introduces some signal loss . but ok with good dipole external antennas.

4. You should use "10k+LED" for indication of Vcc, On-Off,TX,RX, etc. This indication helps in quick visual  fault finding or working of the stage. It helps a lot during the development stage. If current consumption is an issue then later on remove it.

5.I will be listing all the switches usage. Relay, Diode, NE555, 1N4148, BC548,1N4007.




QSK

TRansceiver

VK3YE 

It has RF amp, Ground switch 
and Control voltage

Another QSK


VK#YE VXO


Sunday, December 16, 2018

7159kc again !

Here is my latest 7159kc xtal based CW transmitter.
And 4diode  product detector or ta7358ap  DC RECEIVER IN MAKING.
I made chassis years ago and it was sitting around. Made the 2watt linear.The xtal 7.159mhz cw oscillator  small single transistor tx board was also made earlier. see relevant post back in time.

I was wondering if, i can put a xtal transmitter on air and come up on-air with cw. I had plenty of 40 meter 7159kc DC as well as 3579kc xtal based poliakov receivers. Interesting. I can put my another local ham into air with me to practice my slow cw skill.

logically i started building it. humm ..... with a big linear it produced around 15 watts. it can surely punch a hole through India. i can put dipole, random  longwire as well as EFHW vertical also.

Date 14-12-2018:---Then i started building the suitable box for linear as my previous experience with unboxed linear was that i broke two IRF640 mechanically. It did not breakdown due to heat or vswr !

i was making a box with a big fan, where i can put the linear board as we do in cabinet. But, that building experiment failed due to mechanical problems. Then i said lets do logical work. linear is working. we will put into box later on.

 Meanwhile i started searching the net and fake buck groups to find a c language code for Arduino to key my call in cw. CQ CQ CQ DE VU3INJ VU3INJ VU3INJ K  and in this quest, good hams helped me and lead me to various arduino based keyers. Wow. i said this is good keyers but my Task can be done even with the multivibrator driving relay which keys my tx on off.  So finally, i settled for a simple sketch which keys my tx. will upload that to my uno board and then explore digitally. but that will take time.

Date 18-12-2018:---Antenna is not ready, receiver is not ready. earlier i had bad results using the good receiver in vicinity of transmitter. So i will be using portable homebrew receiver and FSM to measure its LOCAL range. Second thing i want basically a point to point communication around 100km. two places are of my interest. one is my another home and my kids hostel.

Date 19-12-2018:--- I am trying out the QSK for receiver. i do not want any relay chatterings. Its clattering is not good for this small receiver. I will be using a diode based QSK which is well tested by my dear old friend VU2ATNs  in his 20 meter CW QRP transmitter. Fact is that, for the first time i etched the pcb and made a cw transmitter for a college project. OM Atanu is good ham and he published many ckt in Electronics For You Magazine. But in bitx bandwagon his projects did not get much publicity.
QSK

The receiver is a very modular approach. I made various modules over the time.I had a box full  boards from these i found two working modules. I am using jumpers etc so when i do want to replace any AF, PD board etc its just remove the wire and its done. Will try ring-diode based receiver as well as TA7358ap based receiver.  I am steadily working. My office-room looks like a scrap room. My client wondered that are you started dealing in radio repair ? Nope. Anyway.

I was in deep pain . It was physical one. There is some stomach problem and it itches. Then i heard that my beloved ELMER  vu2dev is SK.  In-fact i wanted to have QSO with him on my new TX RX. But alas that could nit happen.Anyway its better to finish it now.

On date 25 dec the xmus is coming here and i want to make QRM still rx is lagging by. Solved the diode series switch issue.  It reduces the antenna input going to ta7358 drastically but still it leaks. So i need a controlled gain rf amp and diode switch . filter tanks. Ohh Jesus, lots of work. :)

The dummy loads problem solved, RF indicator LED not lighting ? So i removed the 0.1 mfd cap and presto the LED lights up on RF. Good.

Fitted the receiver in place. Tested both the boards. I had made them on 2015 imagine 3 years they were sitting idle. Now show time. Solved dry connection. Put connectors. Okey and somehow my new soldering iron gone qrt. Tested rx without any front end. Ok. It can withstand rf. Time to put up qsk and then change xtal to 7024KC with RIT.

Now lets solve the  QSK . I will use the switch as suggested by m0dgq.

Its simple when diode is given firward dc bias it conducts and has low resistance. When reverse biased it has high resistance and blocks the passing of RF.  Higher the frequencies less the separation.  Bulkier the diode less usable in rf. We use back to back diode to get greater separation. Thats it folks. Now time to make rf switching filter tuned ckt FRONT END CARD. As antenna will be big there will be BCB. And QRM . So filter and amp needed.

Wait folks. I have requested a very seniour ham to give me some 7059 xtals. but i doubt it will ever arrive.



;-date 31 dec 2018.  Finally boxed up whole set up and trying to do some qrm-party.  I noticed few problems.
1- Loose connections due to homemade connectors.
2- RF is being leaked from keying amp  to succedding stages. So xtal osc needs to be keyed.
3- It seems antenna is not connected to RF fron end
4- I need to use relay to derive Tx-Rx voltage and Antenna Tx-Rx handover. Despite all these qsk diodes i need the relay.
5- For practical use the VXO is needed. Time to change vxo and rf amp.  Otherwize its good as standalone beep beep beep.

The 2Watt linear is OK when used with my 2 amp 12v DC supply the Vcc voltage line do not drop and i can get good power. at 12vdc 650ma current. and at key down 20 ma. Good enough for tx chain.  At present loading the antenna - a random wire of about 50 feets just 10 feet high. It does not show up in crude FSM made of diodes but its sounds OK in the DEV 40 meter analogue receiver without any antenna.

I will once again make the QSK ckts and see that whether the receiver gets the antenna. Thats it folks. So listen to my canary bird singing beeps on 7159kc. Thats it folks. End of this phase. The Tx-Rx are working. The wheel has been re-invented and re-used or abused. Its working. ENJOY.

Tuesday, November 13, 2018

IRF510 linear 2018


I wanted to make a small linear fact is a small TX system of course CW , beacone for my wish to reach 100km. Here i saw small linear. Hmmm its similar to my earlier experiments. Gave thought.




Then openeded my components BOXES. Yep i have original IRF510 from ine of my lemington road raids. Heatsink ok. Used All components  which i could find in boxes.  There are two pictures of course with beautiful womans.
First day placed the components during day time. My spectacles were broken so had hard time at seeing colourcodes but anyway i use digital multimeter. Finally put components.

Here is ckt diagrams.

Soldered, had a final visual inspection and behold on veroboard i forgot to put ground rail to sourse of IRF.  Soldered.  At night 2 am finished ├ánd load resistor connected. Applied  12v dc . LED ON. Anyway i had used 1N4007 protective diode.  Preset was at half position and it registered around 5-6 mili amp wuiesent without any rf applief and around 250 mili amp when RG apllied. Resistor becomes instantly warm. More than 1watt. When i put preset at max voltage current increased to around 290 mili amp.  Resistors instantly heats up. Line Voltage drops to 10volts. Hmmm .,,,

Put on metal plate. I am done. I dare not to put it on long wireantennas.  I will drive it to a big linear to produce around 15 to 25 watts RF.


Here is my linear running around 15 watt now question is to put it on AIR 7159kc (+\- 5 kc)


Well i had good time.

Will update