AM TX Design. - UK Vintage Radio Repair and Restoration Discussion Forum

cendoubleu · 24th Jan 2009, 9:11 pm

Split from this thread:-

https://www.vintage-radio.net/forum/...ad.php?t=36637

----------------------------------------

I guess this may be a question for the homebrew area and please reassign mr moderator if you see fit, but does anyone know of an AM TX design(possibly SSB but maybe too hard)?

Charlie

Station X · 24th Jan 2009, 9:20 pm

Valve or transistor? Power output?

cendoubleu · 24th Jan 2009, 9:37 pm

Oh most definitely valve

g3yuh_ron · 25th Jan 2009, 10:12 am

SSB valve is certainly not for beginners, best intro would be high level DSB I would think, fairly straighforward and good fun...

Ed_Dinning · 25th Jan 2009, 11:18 am

Hi Charlie, try the various RSBG handbooks from the 40's to the 70's. The ARRL ones as well. There may be some in your local library, but they are often offered for sale. If Birketts are still going in Lincoln they may have some.
They are also a very good primer on radio/ electronics theory generally.
Let me know if you need any bits as I have some transmitting varailble caps as well as transformers etc.
Depending on power. frequency, etc you will be using I would suggest going for an 807 output valve. Rugged and easy to obtain.

Ed

cendoubleu · 25th Jan 2009, 12:52 pm

Thanks for all the suggestions folks. I am keeping a lookout for an RSGB handbook and indeed did buy one before Xmas from Ebay. Unfortunately I hadn't noticed it was the part 2 one which mainly covers antennas etc. Birketts doesn't appear to have any books these days. Thanks Ed for the offer of parts, most appreciated.
All these ideas are just musings at the moment and I think I may actually build myself a valve-based receiver first as I haven't built any valve equipment since an 0-V-0 regen in my teens. I have built a few s/s receivers and a 40m s/s SSB transceiver which worked reasonably well. First thing to get together is a power supply, most of the parts for which I have out of a defunct valve sig-genny. Thinking of various voltage outputs using zeners.

Charlie

Oldtimer74 · 26th Jan 2009, 12:54 am

Hi there. What about making a replica of the AT5 TX. Quite simple and suitable parts not difficult. Circuit available if you want it. I can work all over the UK on 80m with one running about 7 watts.

Pat G3IKR

HamishBoxer · 26th Jan 2009, 12:43 pm

Hope i am not too far off topic Pat,but what antenna do you use? Regards David GM8JET

Skywave · 26th Jan 2009, 1:49 pm

Quote:

Originally Posted by cendoubleu

. . . but does anyone know of an AM TX design ?
Charlie

Hi Charlie,
This looks just like what you're looking for: click on the following link:

http://www.eddystoneusergroup.org.uk...ewsletters.htm

and then scroll down to "EUGN89" - and open it. It's a PDF file.

This is an electronic copy of the Eddystone "Lighthouse" Magazine Issue 89, Feb. 2005. It features a simple AmRad valve TX designed by Graeme Wormald, G3GGL. I haven't tried it myself (yet), but I would be interested to hear of the results of other people's efforts.

Al / Skywave.

Oldtimer74 · 26th Jan 2009, 6:20 pm

David. I use a half wave centre fed with open wire line at about 40ft. Have good earth system here, consisting of about 100 ft of old pyrotenax cable buried about 2 ft under the aerial - heavy clay soil - although I am told that with a half wave the earth does not matter. I think it makes a lot of difference.
Always monitoring 3.615 when in shack.
Pat

Ian - G4JQT · 26th Jan 2009, 7:02 pm

Have you thought of making a "Chinese Copy" of the Codar AT5? Well proved, 1960s/70s AM 160/80m tx. Gives about 7 watts of RF output. Could be optimised for 80m.

I doubt any of the parts are impossible to substitute and the crystal oscillator from "EUGN89" above could probably be used instead of the VFO if you wanted.

Needs crystal mic but inserts available from cpc.farnell.com

I have all data if needed.

Regards,

Ian

John M0GLN · 26th Jan 2009, 9:06 pm

Quote:

Originally Posted by Skywave

http://www.eddystoneusergroup.org.uk...ewsletters.htm

and then scroll down to "EUGN89" - and open it. It's a PDF file.

This is an electronic copy of the Eddystone "Lighthouse" Magazine Issue 89, Feb. 2005. It features a simple AmRad valve TX designed by Graeme Wormald, G3GGL. I haven't tried it myself (yet), but I would be interested to hear of the results of other people's efforts.

Al / Skywave.

If you are considering making one of these, as I am thinking of doing, there are some further thoughts from Graeme on the Xtal oscillator and speech amplifier in issues 90 and 94.

John

cendoubleu · 28th Jan 2009, 7:45 pm

Thanks for all the ideas and links; given me plenty to read and think about. Espcially nice to see all the eddystone newsletters available with all that info. Interesting also about the Codar transmitter. I have seen these for sale on occasion and appear to have reached collectable/'cult' status judging by the prices so I think 'homebrew' would be the way to go on that one.

Thanks once again to all

Charlie

Oldtimer74 · 30th Jan 2009, 1:11 am

There is an AT5 on Ebay at the moment reasonable price but worth looking at.
Pat G3IKR

cendoubleu · 30th Jan 2009, 8:11 pm

Pat

thanks for the info I'll keep an eye on it.

Charlie

24th Jan 2009, 9:11 pm	#1
cendoubleu Tetrode Join Date: Jan 2007 Location: Lincoln, Lincs. UK. Posts: 94	AM TX Design. Split from this thread:- https://www.vintage-radio.net/forum/...ad.php?t=36637 ---------------------------------------- I guess this may be a question for the homebrew area and please reassign mr moderator if you see fit, but does anyone know of an AM TX design(possibly SSB but maybe too hard)? Charlie

24th Jan 2009, 9:20 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: AM TX Design. Valve or transistor? Power output? __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Jan 2009, 9:37 pm	#3
cendoubleu Tetrode Join Date: Jan 2007 Location: Lincoln, Lincs. UK. Posts: 94	Re: AM TX Design. Oh most definitely valve

25th Jan 2009, 10:12 am	#4
g3yuh_ron Retired Dormant Member Join Date: Jan 2009 Location: Margate Posts: 19	Re: AM TX Design. SSB valve is certainly not for beginners, best intro would be high level DSB I would think, fairly straighforward and good fun...

25th Jan 2009, 11:18 am	#5
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: AM TX Design. Hi Charlie, try the various RSBG handbooks from the 40's to the 70's. The ARRL ones as well. There may be some in your local library, but they are often offered for sale. If Birketts are still going in Lincoln they may have some. They are also a very good primer on radio/ electronics theory generally. Let me know if you need any bits as I have some transmitting varailble caps as well as transformers etc. Depending on power. frequency, etc you will be using I would suggest going for an 807 output valve. Rugged and easy to obtain. Ed

25th Jan 2009, 12:52 pm	#6
cendoubleu Tetrode Join Date: Jan 2007 Location: Lincoln, Lincs. UK. Posts: 94	Re: AM TX Design. Thanks for all the suggestions folks. I am keeping a lookout for an RSGB handbook and indeed did buy one before Xmas from Ebay. Unfortunately I hadn't noticed it was the part 2 one which mainly covers antennas etc. Birketts doesn't appear to have any books these days. Thanks Ed for the offer of parts, most appreciated. All these ideas are just musings at the moment and I think I may actually build myself a valve-based receiver first as I haven't built any valve equipment since an 0-V-0 regen in my teens. I have built a few s/s receivers and a 40m s/s SSB transceiver which worked reasonably well. First thing to get together is a power supply, most of the parts for which I have out of a defunct valve sig-genny. Thinking of various voltage outputs using zeners. Charlie

26th Jan 2009, 12:54 am	#7
Oldtimer74 Rest in Peace Join Date: Apr 2008 Location: Worcester, Worcestershire, UK. Posts: 330	Re: AM TX Design. Hi there. What about making a replica of the AT5 TX. Quite simple and suitable parts not difficult. Circuit available if you want it. I can work all over the UK on 80m with one running about 7 watts. Pat G3IKR

26th Jan 2009, 12:43 pm	#8
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,932	Re: AM TX Design. Hope i am not too far off topic Pat,but what antenna do you use? Regards David GM8JET

26th Jan 2009, 6:20 pm	#10
Oldtimer74 Rest in Peace Join Date: Apr 2008 Location: Worcester, Worcestershire, UK. Posts: 330	Re: AM TX Design. David. I use a half wave centre fed with open wire line at about 40ft. Have good earth system here, consisting of about 100 ft of old pyrotenax cable buried about 2 ft under the aerial - heavy clay soil - although I am told that with a half wave the earth does not matter. I think it makes a lot of difference. Always monitoring 3.615 when in shack. Pat

26th Jan 2009, 7:02 pm	#11
Ian - G4JQT Octode Join Date: Jun 2004 Location: Reading/Fakenham, UK. Posts: 1,323	Re: AM TX Design. Have you thought of making a "Chinese Copy" of the Codar AT5? Well proved, 1960s/70s AM 160/80m tx. Gives about 7 watts of RF output. Could be optimised for 80m. I doubt any of the parts are impossible to substitute and the crystal oscillator from "EUGN89" above could probably be used instead of the VFO if you wanted. Needs crystal mic but inserts available from cpc.farnell.com I have all data if needed. Regards, Ian

28th Jan 2009, 7:45 pm	#13
cendoubleu Tetrode Join Date: Jan 2007 Location: Lincoln, Lincs. UK. Posts: 94	Re: AM TX Design. Thanks for all the ideas and links; given me plenty to read and think about. Espcially nice to see all the eddystone newsletters available with all that info. Interesting also about the Codar transmitter. I have seen these for sale on occasion and appear to have reached collectable/'cult' status judging by the prices so I think 'homebrew' would be the way to go on that one. Thanks once again to all Charlie

30th Jan 2009, 1:11 am	#14
Oldtimer74 Rest in Peace Join Date: Apr 2008 Location: Worcester, Worcestershire, UK. Posts: 330	Re: AM TX Design. There is an AT5 on Ebay at the moment reasonable price but worth looking at. Pat G3IKR

30th Jan 2009, 8:11 pm	#15
cendoubleu Tetrode Join Date: Jan 2007 Location: Lincoln, Lincs. UK. Posts: 94	Re: AM TX Design. Pat thanks for the info I'll keep an eye on it. Charlie