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Title: interesting modulator driver ? Post by: Opcom on August 15, 2009, 11:57:54 PM Picked up this small amp today. Four 6V6's in PP Par. Unfortunately it has been very bastardized and the result was a burned out power transformer. I can replace that. But what is so strange is the circuit.
I keep looking at it, and wondering where the input for the 6V6 grids is. Is it an amp at all? If not, what is it? Title: Re: interesting modulator driver ? Post by: K4TLJ on August 16, 2009, 12:35:59 AM Siren? Audio frequency power oscillator?
Title: Re: interesting modulator driver ? Post by: k4kyv on August 16, 2009, 12:37:28 AM The thing I would question is the .002 1600v capacitor across the primary of the output transformer.
Siren? Audio frequency power oscillator? You're right. I overlooked that the input and output transformers are the same transformer. This is obviously not a wide frequency range amplifier but some kind of oscillator. Title: Re: interesting modulator driver ? Post by: WQ9E on August 16, 2009, 10:50:57 AM Perhaps the recording bias and erase oscillator for the Jolly Green Giant's tape deck? ;)
Title: Re: interesting modulator driver ? Post by: W7TFO on August 16, 2009, 12:27:54 PM With the output ability of a quad of 6V6's, I'd say it was for driving either an AC motor or some type of resonant inductive device. Ampex used a similar scheme for variable speed on tape decks.
Title: Re: interesting modulator driver ? Post by: WBear2GCR on August 17, 2009, 09:50:04 AM Pull the grids off that output xfmr's second winding, bias them, (I'm not a self bias fan in power stages...), xfmr couple that and you may have a good audio power amp... or modulator...
_-_- Title: Re: interesting modulator driver ? Post by: KB3DKS on August 17, 2009, 03:33:31 PM Pat,
Are you sure that the output transformer can contains ony one transformer? I have a couple unknown mfg. transformer units that actually contain two transformers. One of them has a power unit and a choke while another has what could be an output and driver mounted as non coupled. Bill, KB3DKS in 1 Land Title: Re: interesting modulator driver ? Post by: Opcom on August 18, 2009, 12:35:11 AM I don't know anything about the transformer yet. It is interestingly rectangular. Time permitting, I can supply B+ and 6.3V from an adjustable regulated power supply and see what happens. The one windng there with such a low DCR I would guess I should swamp with a 10 ohm resistor or so in case anything takes off.
Title: Re: interesting modulator driver ? Post by: DMOD on August 18, 2009, 09:37:54 PM I think it's either a an Old Civil Defense siren driver or a sonar driver.
Phil - AC0OB Title: Re: interesting modulator driver ? Post by: w4bfs on August 20, 2009, 03:42:36 PM the 5 pin connectors were used in electronic organ accessories .... the sharing of a core might have been some sort of cost reduction along with negative fb ... a lot of Hammond amps used pp-parallel 6v6's ....just a possibility ...73 ...John AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
ps ... I STILL wanna shop at Patricks' sto |