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Homebrew Transmitters & Power supplys

PostPosted: Sun Sep 09, 2012 5:59 pm
by KB3WYZ
Hi All, Just wondering if any of you folks like to build your own Transmitters and power supplys?
I have built Three Transmitters so far. All were tube type and CW only.
Just wondering if anyone has a schematic for a transmitter using a 6aG7 and two 807's for
the finals?
Gary, KB3WYZ

Re: Homebrew Transmitters & Power supplys

PostPosted: Sat Sep 22, 2012 11:53 pm
by k8jd
Looking back 51 years, I built a single tube 80M transmitter when I was 16 years old. It came from plans in a magazine. Most of the parts came from junk TVs and radios people gave me. I used a cigar box as the chassis since I had no metal working tools or skills. It worked !
The next year I got an ARC/5 transmitter and had to build a power supply to run it 'then after I found it was chirping badly I had to add a tube based voltage regulator for the osc and final screen voltage. That worked too.

Re: Homebrew Transmitters & Power supplys

PostPosted: Sun Nov 04, 2012 6:08 pm
by K1NV
Hi Gary,
I haven't seen any replies to your query about 807 transmitters, so since I just joined the forum, I'll make a comment.

You can peruse the old ARRL handbooks from the late 1940's and 1950's to find some nice homebrew ideas. The 807 can be a little difficult to tame in the higher frequency bands, but it will do a good job on 80 and 40M. I have built transmitters with an 807 and 1625 (12V fil.) with good success. A pair of them should give you a good solid 60-80 watts out with 600-700 volts on the plates. One of the early WRL Globe series transmitters used a pair of them and the WW II Command transmitters used a pair of 1625's.

It's a good idea to recess the base of an 807 below the chassis to help isolate the grid tank from the plate tank to aid in stability. Keep the leads short and use a generic "parasitic suppressor" at the plate cap connection to swamp out any VHF oscillations that might develop. A 6AG7 should drive two class C tubes adequately but it would be good to add a buffer stage between if you intend use on the higher frequency bands. The 807 will work above 6 meters, but there are better tubes for that range that will provide greater efficiency.

Good luck with your project.

Jon, K1NV 2609-T

Re: Homebrew Transmitters & Power supplys

PostPosted: Tue Nov 06, 2012 6:55 pm
by KB3WYZ
Hello Jon,
Thanks for your kind responce. I don't think this
forum is to active, I have posted several comments and
questions and never heard anything back.
About the 807 project, it is coming along alright, I have the
power supply built already. It has 800VAC/CT and a 6.5VAC@3.5a and 5VAC @ 5a.
so that should drive the two 807 finals.
Yes, I always have my eyes open for old ARRL mag's and old Popular electronics
from the 50's and 60's.
I am 68 years old and trying to master CW....Not to easy. I just got a heathkit DX-60B
xmtr and a VFO on ebay. My SKCC # is 9595 And I have been sending out CQ"S on 7.114
Don't know if anyone hears me or not...I can't copy all that good yet!
I use a cheat sheet to send out my call sign and SKCC #.
If you have any 50's ARRL books I would be happy to buy them.
Regards, Gary
KB3WYZ

Re: Homebrew Transmitters & Power supplys

PostPosted: Mon Dec 03, 2012 5:19 pm
by k8jd
Hi Gary, I think we finally had a QSO on 40m. Keep signed in on the K3UK SKCC page or Elmer page to find people to QSO lwith and above all,
LISTEN for QRS QSOs you can copy and get familiar with the procedures to follow in a QSO and in Calling a CQ.
Best of luck with your transmitter project. My first attempt in building was a 6AG7 Xtal osc driving a single 807 final. (I was 16 years old then)
It never worked.,
Next I built the single 6AQ5 Xtal osc that ran 6W DC power and got out all over the midwest on 80M !
I also built a HV power supply that had exploding filter capacitors (under voltage ratings) that frightened my mother who thought I would eventually kill myself .