> -----Original Message-----
> From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
> Behalf Of Joe Subich, W4TV
> Sent: Thursday, June 29, 2006 10:36 PM
> To: 'Gary Schafer'; amps@contesting.com
> Subject: Re: [Amps] IM distortion and such
>
>
>
> Gary writes:
>
> > That is exactly Rich's point. The degree of loading has no
> > effect on VHF energy.
>
> Gary, you make the same mistake Rich does ... the voltage is
> not necessarily due to parasitic oscillation at VHF frequencies.
> An unloaded tank can generate voltages several times that of the
> applied (plate supply) voltage depending on the Q and impedance
> transformation. Since the tube is not operated in class A,
> harmonics will be generated and, particularly at 10 meters,
> some of those harmonics will certainly extend to VHF (3 x 28
> = 84, 5 x 28 = 140). Again, that is expected behavior.
>
> What is important is that the tank be properly loaded, the
> components be designed to withstand the normally generated
> voltages and reasonable care be taken to prevent the tube
> from turning into a TPTG oscillator at some unknown frequency.
>
> 73,
>
> ... Joe, W4TV
Joe, I am only addressing your statement that "heavier loading may reduce
VHF parasitics".
73
Gary K4FMX
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