Bob,
It seems that the plate modulator type hams look down at those running AM
Linears! It would be interesting to run the numbers to look at heat radiated
into the hamshack for say a globe king 500 pumping out 350 watts carrier, and
a SB-220 putting out the same, and driven from something like a Heath DX-60
with the carrier control removed. We all know both would heat the shack
considerably. How much more though from one over the other?? I'm talking about
total heat dissipated including filament power, bleeder resistors, plate
dissipation, etc.
Now for that 6 DB that is not detectable. When listening to a signal under
marginal conditions at the threshold of being copyable, that extra S unit or
about 6 DB is huge.
I'd say let Cory run his amplifier, and maybe chip in a suggestion or two on
how to maximize the linearity, and stability of the setup. For example a audio
feedback loop from the SB-220 RF out (add a detector circuit) to the modulator
audio chain to straighten out the trapezoidal pattern as seen on a scope. The
linear won't be perfectly linear, so this technique if done well can really
help clean up the signal and reduce bandwidth by reducing the distortion
products.
BTW on my QRO 20A project I am doing just that to linearize the single EL-34
output tube which runs AM linear AB1 mode to provide 10 watts RF carrier
output. A 6DB reduction in audio gain from the feedback has a considerable
effect on the modulated envelope (matches the low level waveform much closer)
and increases the maximum PEP power some for a given amount of gain compression.
Regards,
Jim
WD5JKO
RJ Mattson <[EMAIL PROTECTED]> wrote:
If your Viking II runs 100 watts, 400 watts will give you about 1 s-unit
gain. Not even detectable unless you look at the meter.
Could be helpful during the winter months as a supplemental room heater.
bob...w2ami
----- Original Message -----
From: "Cory Hine"
To:
Sent: Sunday, September 26, 2004 2:13 PM
Subject: [AMRadio] WTB SB-220
> Hey gang,
>
> I am looking for a Heathkit SB-220 to run about 300 watts on AM using the
Viking II to drive it. Does anyone have a decent amp that they want to sell?
I would like pics if possible.
>
> Thanks,
>
> Cory/AD5QP
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