[AMPS] Advice about what linear to buy

Tom Rauch W8JI@contesting.com
Mon, 8 Jan 2001 20:46:31 -0500


Barry wrote:

> I beg to differ.
> I used the term "all things being equal".
> Hence issues of shielding integrity, supply regulation and tuning apply in
> the hypothetical case of the amplifier being pushed close to its limits
> and a larger one working on the linear part of its transfer curve.

OK, I stand corrected!

All things equal, the higher power amplifier will have more TVI and 
more IMD.

> distortion products. Also in the real world the budget amps tend to be
> poorly shielded and lack features such as vacuum variables which typically
> show lower impedance to vhf than breadslicers do, hence the tanks work

........and you know that because?

Factually, air variables can and do offer very low impedances to 
VHF. As a matter of fact, the impedance is often comparable at 
VHF. Vacuum caps have lower ESR, but in this application that 
isn't important.

It's more important how parts are laid out than how expensive they 
are. 

> considerations apply to audio amplifiers: the overbuilt ones look better
> when the output is analysed and sound better to the ear. Also issues of

That's because audio amps, unlike RF amps, freely pass harmonic 
distortion on to the load. That's why a single-ended class AB amp 
is just as clean as push-pull in RF, but a single-ended amp is 
dirtier at audio.
73, Tom W8JI
w8ji@contesting.com

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