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24th Jan 2009, 9:11 pm | #1 |
Tetrode
Join Date: Jan 2007
Location: Lincoln, Lincs. UK.
Posts: 94
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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 |
Moderator
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,289
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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 |
Tetrode
Join Date: Jan 2007
Location: Lincoln, Lincs. UK.
Posts: 94
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Re: AM TX Design.
Oh most definitely valve
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25th Jan 2009, 10:12 am | #4 |
Retired Dormant Member
Join Date: Jan 2009
Location: Margate
Posts: 19
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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...
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25th Jan 2009, 11:18 am | #5 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,195
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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 |
Tetrode
Join Date: Jan 2007
Location: Lincoln, Lincs. UK.
Posts: 94
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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 |
Rest in Peace
Join Date: Apr 2008
Location: Worcester, Worcestershire, UK.
Posts: 330
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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 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,935
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Re: AM TX Design.
Hope i am not too far off topic Pat,but what antenna do you use? Regards David GM8JET
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26th Jan 2009, 1:49 pm | #9 |
Rest in Peace
Join Date: Jun 2006
Location: Chard, South Somerset, UK.
Posts: 7,457
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Re: AM TX Design.
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. |
26th Jan 2009, 6:20 pm | #10 |
Rest in Peace
Join Date: Apr 2008
Location: Worcester, Worcestershire, UK.
Posts: 330
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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 |
Octode
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,324
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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 |
26th Jan 2009, 9:06 pm | #12 | |
Octode
Join Date: Jan 2004
Location: Southport, Merseyside, UK.
Posts: 1,156
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Re: AM TX Design.
Quote:
John |
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28th Jan 2009, 7:45 pm | #13 |
Tetrode
Join Date: Jan 2007
Location: Lincoln, Lincs. UK.
Posts: 94
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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 |
Rest in Peace
Join Date: Apr 2008
Location: Worcester, Worcestershire, UK.
Posts: 330
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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 |
Tetrode
Join Date: Jan 2007
Location: Lincoln, Lincs. UK.
Posts: 94
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Re: AM TX Design.
Pat
thanks for the info I'll keep an eye on it. Charlie |