Yes the 9v battery method does work. I was only saying that any
amp even at reduced drive levels will amplify the signal and anything
else like noise into it. Gozinta gozouta. If that amp has imd problems
it won't show until at or near full power. If it's the rig, the imd will be
present even at reduced levels and of course the amp will amplify
everything. I also agree to keep the 100w rigs around 85w which
will greatly reduce distortions. As you know though, most amps
today only need 35-50w for full power levels anyway, so if the
driver has rice inside, it will most probably have some anomaly
whether it's spikes or pure imd. Either will sound like crap through an
amp regardless.
Sent from my iPad
> On Apr 25, 2017, at 10:31, Jim Thomson <jim.thom@telus.net> wrote:
>
> Date: Tue, 25 Apr 2017 10:55:15 -0500
> From: "Gary Schafer" <garyschafer@largeriver.net>
> To: "'Thomas Walsh'" <w2co@comcast.net>, <amps@contesting.com>
> Subject: Re: [Amps] Price per Watt Conversation
>
> Not necessarily.
> When an exciter with IMD is connected to an amp that produces IMD there can
> be a sum or difference of the two levels of up to 6 dB of the IM levels.
> So it is possible that the overall IMD level can be less.
>
> This summation is for equal levels of IMD produced by the amp and exciter.
> Worst case is up to 6dB greater overall IMD and best case is 6dB better
> overall IMD.
>
> 73
> Gary K4FMX
>
> ## agreed. At least thats what the experts at collins say.
> Some xcvrs have bad overshoot, some dont. My fix for that
> is just to use a 9 vdc battery across the ends of a 100K pot. Then
> the wiper goes to the alc input on the xcvr. Positive of battery goes to
> xcvr chassis. 0 to –6 vdc is all you require to control most xcvrs.
> Then you can dial up how much alc voltage you want.
> You dont have to wait to develop alc voltage internally, or from an amp. Its
> now fixed..and sitting there all the time.
>
> ## set the po for say 85 watts...then scream all you want, with all knobs to
> the
> right and it will never exceed 85 watts...or what ever level you set it for.
>
> Problem solved. NO spikes or overshoots ever...plus precise power output
> control. 9V / 100k = .00009 amps...which is dick. 90 microamps.
> Battery will last forever. Simple and effective fix. Put a spst switch in
> series
> with the battery, and shut the battery off, when not in use.
>
> ## Most 100 w xcvrs have so-so imd, when run at 100w. back it off to 85w,
> and imd improves a bunch. Back it down to 50 watts, and imd improves a bunch
> more.
> A 100w K3 has min IMD when run at 30 w output. They all have a sweet spot
> for min
> IMD. Same deal with a 200w xcvr. When run at 100-150w, imd greatly
> improves.
>
> Jim VE7RF
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