>
> IMD reduces a bit as regulation improves but how much? Ive asked you this
> many times but never an answer.
>
> ## You are the guy with all the spectrum analyzer gear you tell us. BTW,
> any normal 2 tone test wont show anything! Why, cuz everything is in a
> steady state ! Your B+ doesn’t budge, and neither does the bias V..nor
> screen
> V etc. So a standard 2 tone test is useless.
>
>
>
>
> With most store bought amps having 8-12% idle current to full PEP
> regulation how much IMD improvement is there in each 1% improvement? The
> few
> tests Ive done here using the eyeball and then the Peak Hold method on the
> SA while inputting a voice track into the exciter shows under 1dB using a
> TS-940 and TS-950SD which have excellent IMD to start with....sometimes
> better than the amps published specs.
>
> ### use a Class A yaesu to run the peak hold SA test, while inputting a
> voice track.
> Ok, then run the test again.. driving the store bought amp..... GG triode.
> Do it with 200 uf caps... then repeat using 600-2500 uf caps. While ur
> at it,
> measure the pep output of the amp. You wont get any 12% drop.
>
> Later... Jim VE7RF
>
>
> Carl
> KM1H
** The tests Ive run were replacing the 200uF in various Heath SB series
amps with 330 or 470uF, with and without directly grounded grids in the
3-500 amps. Plus a few other brands going from the stock 160-170 uF to the
same values. Those amps were 3-500, 8874, and 3 x 3CX800A7.
Any differences are within interpetation margin of error and inconclusive.
While the PEP went up a bit so did the strain on otherwise marginal
transformers in some amps and noticably not as much as those with HD
transformers such as my LK-500ZC with the external 46# Dahl transformer
PAC-5 option.
I dont see any real benefit in using caps that offer no noticable
improvement on the air using normal SSB with commercial amps.
Carl
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