>
>Rich said:
>
>"It seems a bit doubtful that the 4CX1000A has c. 100-times as much 3rd
>order distortion as a 4CX1500B"
>
>The data I mentioned regarding the 4CX1000 and the 4CX1500 comes from:
>
>Care and Feeding of Power Grid Tubes copyright 1967 by Varian - Thrid
>Printing 1978.
>
>On page 64, under the heading 4.3 "Selection of Tubes for Single Sideband
>Service", it is stated that "As a guide in selecting tubes for various power
>levels of single-sideband service, typical operating conditions for various
>EIMAC tubes are included in this section. ... Typical third and fifth-order
>intermodulation distortion product levels for maximum drive conditions are
>also given for the two-tone condition.
>
>In the "guide", I found the following information.
>
>4CX1000A/K @3000 volts yields -23 db 3rd order and -26 db 5th order
>distortion
>
>4CX1500B @ 2900 volts yields -44 3rd order and -48 db 5th order distortion.
>
>I did not make this stuff up, Rich. I just reported it. Don't shoot the
>messenger if the data does not fall into line with your preconceived notion
of reality.
Your report is ver batim, Colin. The sicky wicket is Eimac's data. I
have seen other errors they made,
>
>On page 22.52 of the 23rd Radio Handbook, edited by William I. Orr, there is
>a 4CX1500B amplifier construction article. In that article, the following
>language appears: "The linear amplifier described in this section is a
>deluxe 2-kw PEP, class AB2 grid-driven amplifier using the low distortion
>4CX1500B tube. This is a ceramic-metal, forced-air cooled tetrode having a
>maximum plate dissipation of 1500 watts. It is designed for exceptionally
>low intermodulation in SSB service."
>
>I knew one ham who ran a 4CX1500B and it was the cleanest amp I ever heard.
// 'tis so clean it makes today's radios look feculent.
>I just wish a local ham - who runs a 4-1000 driven by an overdriven SB-200,
>ran a 4CX1500B operated properly. Unfortunately, my antenna is larger and
>taller and his only way to combat that is to turn up his mike gain. I
>expect he has had splatter reports from at least 100 countries - which would
>entitle him to the coveted DXCCS award.
>
// Guffaw.
In days of yore, when I was active on 80m long-path, there was a turkey
in LA who ran an obnoxiously overdriven (160w) SB-200. He would make
longish calls in hopes of getting through the sunup pileups. This kept
others from hearing the Europeans. To assist this person in getting
through pileups, someone with a tetrode-with-handles amplifier would
deliberately double with the feculent station and say "silver dollar" -
the offender's callsign suffix. If the European station cold hear the
14kW signal in the pileup , he would pick up the feculent station and,
with luck, peace would temporarily return to c. 15kHZ of the DX window.
Was this ethical? At the time, I was a member of the American Radio
Relay League, so why not?
cheers, Colin
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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