this circuit may keep the tubes from oscillating at the operating frequency,
but i fail to see how this can avoid VHF oscillations, since these components
would have no affects there......too much inductance
plus the tube troubles came from the design of svetlana 572Bs, no one uses them
in manufacture anymore
steven
"R. Measures" <r@somis.org> wrote:
Tnx, Steven -- This is the same kind of neutralizing circuit that
both Gonset and Heath tried in their 4, 811A amplifiers and both
promptly abandoned because it increased VHF squirreliness.
- The gotcha is that there is no way to neutralize an HF amplifier on
the parasitic VHF-resonance in the anode circuit. The only game in
town is to artificially reduce the VHF gain of the tube by decreasing
the VHF-Q of the suppressor.
On Dec 22, 2004, at 7:19 AM, Steven Grant, W4IIV wrote:
> it does have a neutralization circuit
>
> steven
>
> "R.Measures" wrote:
>
> On Dec 21, 2004, at 9:02 PM, larry williamson wrote:
>
> > Sorry I did not say the kind of amp.... It is a AL 572... Only about
> 8
> > months old. I just tonight installed the new 51 ohm resistor and one
> > new tube form ameritron. Only tried about a 10 minute chat on 160
> and
> > it seemed to be ok. I will run it more over the next few days and
> see
> > what happens. Both times the amp was on standby for about 1 hour and
> > it blew when I keyed up within the first 10 seconds. The bad thing
> ---
> > I don't have a lot of knowledge of electronics, just the basics.
>
> Larry -- Does the AL-572 have a neutralization circuit? Tnx
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
STEVEN GRANT W4IIV
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