[Amps] Checking for IMD

[Gary Schafer]

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of Tom W8JI
> Sent: Monday, August 14, 2006 2:10 PM
> To: amps at contesting.com
> Subject: Re: [Amps] Checking for IMD
> 
> Hi Gary,
> 
> > My contention of using the other side band is that you are
> > always moving the
> > receiver pass band the same amount every time you switch
> > side bands as
> > opposed to tuning around. You can quickly switch back and
> > forth to compare
> > levels of wanted and unwanted signals. It give you pretty
> > much the same
> > information as you get by tuning but it is very repeatable
> > when checking
> > various signals on the band. You can get a feel for what
> > the signal levels
> > should be on the opposite side band with some practice.
> 
> Why worry about precise repeatability with a rough test?

I don't think I used the word "precise" there.

How far should we then tune away from the wanted signal for any kind of
repeatability? In which direction? Do we tune to several different
frequencies and record the levels at each? How do we correlate that with the
levels of which fundamentals?

> 
> We know now the test initially claimed to measure IM average
> power ratios measures something near peak power, misses some
> of the third order and much of the higher order products,
> and probably isn't useful on the air except under certain
> conditions.

Can you tell us what voice frequencies will NOT be transmitted so we can
calculate which IM products will not be generated at which frequencies?

Is measuring IM products using voice as a source by any means good for
anything at all?

> 
> Is this test explained correctly anyplace? Is it explained
> incorrectly anyplace where it should be corrected?

We are attempting. :>)
What is your point?

73
Gary  K4FMX

> 
> 73 Tom