[Amps] IM distortion and such

[Gary Schafer]

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Joe Subich, W4TV
> Sent: Thursday, June 29, 2006 10:36 PM
> To: 'Gary Schafer'; amps at 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