Monday, January 19, 2015

CW TX 14316kc

RF Linear
Last year made a CW transmitter. Power was very low. So decided to make a linear, then  after a year my cw tx is perfectly working with this  homebrew linear.

Here is the picture.

All details will updated later on. Atleast this is working......( updated as on 27jan)

Main power supply is the 24-0-24 @5amp with 0-12 @1amp . The cheap computer fan is used to cool it. The bottom plat is a thick metal one. Used as a heat sink.

One 12v dc @1amp, white box is used to supply the power to swr meter and keyer. Here the SWR meter requires the reverse polarity power supply.

The open box is exciter with having its own power supply on right had extreme. Well I can drive the exciter from the main transformers... will do that.... one friend said this much power sources.... well its on the assembly bench so I took liberty of using more....

Here is the ckt diagram.

linear amp after modification

(with input 50ohm resistor exciter can not drive amp
so removed the resisotors )

The RF Power Amp is used to drive the inv-v dipole antenna. Antenna is on the roof top....

Inverted-V antenna

On first test, i tried to load the dipole only 12feet from ground. But could not get the report. Well on suggestions, I made another antenna on the top of building. It was not cut to exact freq. Bought 20swg copper wire. 100 gram at rs.60/-. ... Used common dish wire to connect with TX. The plastic tube used as end insulator. Antenna was done in clear hurry..... but it worked well....

Used 20watt RF power. The SWR meter shows me the 3.0 reading. Then 2DEV gave me hint to put the antenna away from rooftop about 10feet with some plastic pole. I used a bamboo. then SWR reduced to 2.6 ok. One important thing I learned that for the receiving you can put dipole anywhere but for transmitting you must put your dipole/inv-v ver high and without any obstructions ( metal building) tree might be not that much trouble....  Put antenna atleast 30feet and up and you can punch a hole with 20watt north to south. For 5watt I got about 55 report. for 20watt about 57 report.

On my request 2KD also suggested few things. Well as the rooftop renovation work is going on will assemble/modify the antenna next week and try to have cw/dsb toway contact.

My test signals could be heard all Gujarat, sought india. But, the central india and Northern india I could not get the report....

What I feel:::   In the secondary school you get your first kiss..... (its different matter I have never got a kiss).

But atlast I have become the transmitting ham. Will modify it to DSB and hook up a receiver.

There are many hams to thanks. They helped me in varous stages of deveoplement by moral supprts, pcb, guidance, critical reports, critical words and above all kept my company....... 2TOO,2KD,2DEV,2UPX, 2PTR,3YFD,OM Ashok khachar, OM Vagishetty, Om Gurudata, 3HMM,3HML,3JOJ,3JOG, Om Mehta- Jamnagar, ( Last year during cwtx exciter time 2RAK, 2ATN,2UUU & 2ESE,3SXT,3SXN,2ORO....) also land lots more..... THANKS.....

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