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Old August 2nd 07, 05:53 PM posted to alt.binaries.pictures.radio,rec.antiques.radio+phono
Jim[_4_] Jim[_4_] is offline
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First recorded activity by RadioBanter: Aug 2007
Posts: 2
Default Design help: Modulator schematic


"Brenda Ann" wrote

As others in the other group have mentioned, you're pushing your luck
with 600V diodes. They have over 700V on them (or they would have if
things were working right). Replace them with 1000V diodes. This also
means you need to replace those capacitors with 1000V capacitors,
preferably AC rated.

As someone else said, you have a major problem with the power supply.
The output voltage should be much higher.

--

I think I have kenned out what that problem IS. It's not a 250-0-250..
it's a 125-0-125 on the secondary.. which would output pretty much what
I'm getting.


This is my transformer. From Mouser

http://www.hammondmfg.com/pdf/5c0030.pdf #261G6
261G6 45250V C.T.@ 130 ma 6.3V @ 2A 1 4.00 2.50 2.63 3.56 2.0



What is the modulation transformer you're using?

If it's a mains transformer it could be going into saturation. Proper
modulation transformers are designed to accomodate a d.c. bias through the
windings which normally requires an airgap in the core. In an ungapped core
the dc bias will drive the core somewhere up the BH curve and the effects
will be exactly as you describe - clipping on one of the peaks