There is such a device and it is frequently used in VHF/UHF systems. It's
called a sequencer. I don't know if anyone has ever adapted them for HF,
but what it essentially does is prevent the radio from sending RF until the
amplifier is keyed. The radio has to be modified a bit in order to do this,
but it isn't that difficult to do.
Downeast Microwave is one of the companies that sell these.
They are popular in VHF/UHF systems because preamps are typically used for
receiving weak signals. The preamps must be switched out of the transmit
path before any RF is applied otherwise they will blow. The sequencer is
designed to control this and I'd bet it can control an HF power amplifier as
well.
73,
Jon
NA9D
on 6/26/01 5:45 PM, carl seyersdahl at carlseye@tampabay.rr.com wrote:
>
> In the world of transmitters and amplifiers, it seems it has always been
> standard procedure to control the amplifier via a relay or other circuit in
> the transmitter(exciter). In modern solid state exciters this generally
> requires a fast switching amplifier circuit, which of course doesn't seem to
> exist. Why then is the system not reversed, ie: make the amp control the
> exciter?? this seems to me to be a simple answer to "hotswitching" amps.
> most exciters today have "accessory connectors" which nearly always contain
> a separate transmit control connection.
> any comments on this??? P.S. I built an amp that way and had no trouble
> with slow switching!!
-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)
Member: ARRL, AMSAT, DXCC, NRA
http://www.qsl.net/ke9na
"A life lived in fear is a life half lived."
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