[Amps] 4CX250 IMD

[jeremy-ca]

----- Original Message ----- 
From: "Tom Rauch" <w8ji at contesting.com>
To: <amps at contesting.com>
Sent: Thursday, September 27, 2007 8:16 PM
Subject: Re: [Amps] 4CX250 IMD


>> At Ep of 1500 in AB1 3rd/5th is -30/35. However at 2000V
>> it slips to -23/27.
>> This is a 2 tone measurement which disagrees with Toms
>> claim of Eimac using
>> a single tone. Maybe they swing both ways (;
>
> Hi Carl,
>
> I actually said  (about a dozen times).......
>
> "Eimac uses two tone IM referenced against a single tone of
> the test. The ARRL uses IM referenced against PEP."
>
> I assumed people know a two tone test is a two tone test
> with two tones, and only the reference point changes. I
> assumed people know that a two tone IM test referenced to
> one tone of the two tones is a standard measurement method,
> which results in 6dB less favorable numbers than a two-tone
> test referenced to one tone of two tones.
>
> For example (excuse my repeating it) a tube with -35dB one
> tone in a two tone test (Eimac's method) is actually -41dB
> using the ARRL method referenced against PEP.
>
> The problem is everyone in the industry in the USA always
> used IM referenced against a single tone in two-tone tests
> and then around the time of the KWM-380 a few people changed
> to dB below PEP. This makes a 6dB discrepancy in the
> results.
>
> A modern radio with -32dB PEP tone IM3 actually is the same
> as -26dB IM referenced against one tone of the two. THEY ARE
> BOTH TWO TONE TESTS.
>
> 73 Tom


I dont read all of your posts, especially when they ramble on and drift off. 
You certainly enjoy mentioning nichrome on at least a daily basis. Are you 
hoping Rich is lurking and youre just needling him? Not nice.

Ive no problem understanding the Eimac method as its the only one Ive ever 
used. It was the ARRL reference that threw me; I dont pay much attention to 
their reviews. So what reference do the ham manufacturers use? The best one 
or the honest one? Or is there no agreement on a standard?

Carl
KM1H