[Amps] Amps Digest, Vol 32, Issue 36

[R.Measures]

note -- Quote level marks corrected.

On Aug 7, 2005, at 3:25 PM, k7fm wrote:

> Rich said:
>
>> "In all other HF 8877 amplifiers they are there.  Was Dick Ehrhorn 
>> and every other 8877 amp mfg out of line for using a parasitic 
>> suppressor?"
>
> Rich, this is an interesting observation.  In the past, you have 
> criticized almost every manufacturer of 8877 amplifiers because their 
> parasitic suppression was not your standards.

In order to reduce VHF gain, parasitic suppressors need to have a 
low-Q.  In your opinion, do Ag and Cu contribute to a low-Q?

> So, if these manufacturers do not know what they are doing, why should 
> they be the standard by which others should be measured.

Even a medium-Q parasitic suppressor is better than no suppressor 
whatsoever.
>
> There are many commecial amplifiers which do not use parasitic 
> suppressors.

Can you name a commercial HF 8877 amplifier besides the AL-1500 that 
does not use a VHF suppressor?

> Old tubes like 811s need them, because of internal construction.  But, 
> the 8877 is a modern tube similar to many of the high power tubes.

So Dick Ehrhorn made a mistake in the Alpha 77 by using a VHF 
suppressor?

> Many high power amplifiers used in commercial services do not use 
> parasitic suppressors.

Surely, but they are likely VHF or UHF amplifiers, not HF.

> In fact, using one may be an admission of either an older tube or a 
> dated design.

The only tube that I have seen that is unconditionally stable  in HF 
service with or without a VHF suppressor is the 813
>
> Colin K7FM
>
>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org