STRANGE TRIPLE STAGE PHANTOM

[Stellasstillarat]

I've always wondered why jb, windjammer, black cat and all the other buiders called these what i always believed to be low output amplifiers , modulators?

what is it that defines it as a modulator and not just an rf amplifier? My Demco absolutely doesn't change my 21/2 watt deadn key on my fs2340 but definitely increases the modulation according to where you put the gain knob.

I gotta say driving a phantom with a jb 75 imo takes balls.
The demco modulator I pictured is probably the best known "modulator" and the Elenco is something I'm looking to add to my collection. I know the Elenco's not a Demco.
It's much more advanced and very rare, but it Is a modulator.
P.s. the Demco's mine. The Elenco Belongs to my friend Mike. If you ever grt a leed on one please pm me I'd appreciate it.

One of the great myths of the D&A Phantom is that it is a 1,000 watt amp. No, it isn't. Going by D&As own information the triple-stage Phantom was rated at 1375 watts INPUT. Assuming 60% efficiency this should give an output of around 850 watts max.

Will they do 1,000? It can sure look that way on some meters. But to do that you would have to drive the snot out of them insuring a dirty, splattery signal and oh yeah- you will be replacing those tubes a LOT faster.

In the old days (before high-output radios) we would put a JB 75 modulator between the radio and the amp. That sure made them swing but the price was more rapid tube replacement.

I run mine with about a 4 w dead key and peaking around 8 watts (around 14 w PEP on SSB) On AM this give me a resting carrier of around 450 w with peaks hitting around 600w. On SSB I've seen it hit around 850 but that's the max.

As stated above, an amp is just going to give you more of whatever you put into it. Clean in = clean out. Run it below it's maximums and it should give years of service. I let mine loaf along and haven't had to replace a tube in about 3 years- except for that one tube behind the final load control!

 

[Atlasta]

You pretty much answered your own question. A modulator will not increase the resting carrier any but it will well - MODULATE the carrier. Gives a LOT more swing. Often they are used ahead of amplifiers.

An amplifier amplifies. A modulator modulates. Can an amplifier work as a modulator? Sure it can but at a higher level. Turn on the amp and hit the dead key, there is one level of output. Start speaking into the mic and watch the meter go up.

A true modulator will not increase the resting carrier much, or at all above stock, but will provide higher output while speaking.

To the untrained eye they appear identical from a component point of view. I don't know what exactly the difference in construction is that makes one a modulator and another an amplifier. But they are two different devices.