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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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1st Sep 2021, 2:41 pm | #21 |
Octode
Join Date: Jun 2004
Location: Reading/Fakenham, UK.
Posts: 1,323
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Re: AM Conversion for CW TX
This is very closely based on the Codar AT5 - I've just changed the VFO for a crystal oscillator. The significant bit for you is probably the audio amp and the modulation transformer which just uses the mains side (with centre tap) of a 15 VA transformer with the secondary windings unused.
(Posting the whole article was easier than explaining the circuit!) |
1st Sep 2021, 4:06 pm | #22 |
Octode
Join Date: Mar 2020
Location: Blackburn with Darwen, Lancashire, UK.
Posts: 1,572
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Re: AM Conversion for CW TX
Just a thought, how about an audio and modulator stage from the TR1998, it has valves and modulation transformers on it, drives a TT15 valve with anode mod. There is a compete stage for sale elsewhere or I could well have the mod transformer on it's own if I can find it.
Adrian |
1st Sep 2021, 7:51 pm | #23 |
Octode
Join Date: Jan 2004
Location: Southport, Merseyside, UK.
Posts: 1,156
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Re: AM Conversion for CW TX
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19th Sep 2021, 12:01 pm | #24 |
Tetrode
Join Date: Feb 2012
Location: Bishop Auckland, County Durham, UK.
Posts: 92
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Re: AM Conversion for CW TX
There is also a complete high level AM modulator available on ebay from time to time. It's from the PTR175 transmitter, and has 2 X 2E26 valves in it complete with mod transformer and audio preamp.
Andy |