> Input power is 500WDC, Output is 470W PEP, not key down CW. I'll use CW
> since some seem to be getting confused with single and two tone
> references.
> Im reading the 470W reference right from the full length 6 page 4CX250R
> spec
> sheet, not a short form catalog or ARRL Handbook.
> Carl
> KM1H
Hi Carl,
I haven't looked at the 4cx250 sheets in a long time so I just looked at the
4cx250B Eimac, 4cx250B STC and 4cx250R Eimac data sheets.
Power should be referred to as PEP and average power, either input or output
to avoid confusion.
Single tone power is the same as CW.
In the spec sheets single tone power is the same as PEP.
When stating IM products referenced to a two tone signal it should be:
"referenced to one tone of a two tone signal.
Saying "referenced to a single tone" gets confused with a single tone only
signal, which can be the same as PEP.
Here are the specs that are being discussed:
4cx250B Eimac sheet.
2000 volts.
Single tone plate current: 250Ma.
Input power: 500 watts.
Output power: 300 watts = 60% efficiency.
* Note that PEP power is equal to single tone power.
Two tone plate current: 190Ma.
Two tone average power input: 380 watts.
Two tone average power output: 150 watts = 39% efficiency.
** Note that the spec sheet does not show the average power output with two
tones applied but two tone power output will be 1/2 of PEP output as shown.
IM products not listed.
----------------------------------------------------------------------------
-
4cx250B STC sheet.
2000 volts.
Single tone plate current: 250 Ma.
Input power: 500 watts.
Output power: 325 watts = 65% efficiency.
* Note that PEP power is equal to single tone power.
Two tone plate current: 175Ma.
Two tone average power input: 350 watts.
Two tone average power output: 162.5 watts = 46% efficiency.
** Note that the spec sheet does not show the average power output with two
tones applied but two tone power output will be 1/2 of PEP output as shown.
3rd order IM = -30Db.
*** IM product are measured in reference to one tone of the two tone signal.
----------------------------------------------------------------------------
4cx250R Eimac sheet.
2000 volts.
Single tone plate current: 375Ma.
Input power: 750 watts.
Output power: 470 watts = 62% efficiency.
* Note that PEP power is equal to single tone power.
Two tone plate current: 245Ma.
Two tone average power input: 490 watts.
Two tone average power output: 235 watts = 47% efficiency.
** Note that the spec sheet does not show the average power output with two
tones applied but two tone power output will be 1/2 of PEP output as shown.
3rd order IM = -23 Db.
It looks as though the IM performance is much worse running at these power
levels than what the spec shows for the 4cx250B. Perhaps the 4cx250 family
gets a bad rap from this type of thing. If they were all run at 500 watts
PEP input they should be as good as any other tetrode.
** If the amp is linear.
73
Gary K4FMX
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