On Fri, 18 Dec 1998 10:52:10 +0200 "John Fielding"
<johnf@futurenet.co.za> writes:
>According to my Eimac shortform the 4CX250R and the 7580W are the same
>tube. BTW the R stands for "ruggedised" it can withstand a lot more
>vibration and shock than a standard 250. However the plate, screen
>and
>grid dissipation are the same as a normal 250 and have the same
>typical
>output power. Eimac catalog for the 4CX250B/7203 & the 4CX250BC/8957
>both
>give typical output power of 300W at 175 MHz in AB1 operation.
>
>In summary:
>
>4CX250B/BC anode 250W
> screen 12W
> grid 2W
>
>4CX250R anode 250W
> screen 12W
> grid 2W
>
>What's the difference?
The 250R has a minute (Eimacs word) .2pf increase in output C over the
7580. Both have a higher perveance than the 250B and require a slightly
more negative bias voltage.
At 1500V Ep any version can be made moderately clean. At 2000V they are
horribly dirty.
The 7580 was developed primarily for military use where communications
are channelized so IMD was not a problem. Listen even today to military
nets if you want to hear poor signals!
73 Carl KM1H
>
>
>John ZS5JF
>
>----------
>> From: km1h@juno.com
>> To: amps@contesting.com
>> Subject: Re: [AMPS] tuning capacitor & insulator
To: <amps@contesting.com>
>> Date: 18 December 1998 08:27
>>
>>
>>
>>
>> On Thu, 17 Dec 1998 16:25:34 -0800 Rich Measures <measures@vc.net>
>> writes:
>>
>>
>> SNIPPED
>>
>>
>> >>No criticism of Rich's particular design; the limitation is in the
>
>> >tubes
>> >>themselves.
>> >>
>> >? Did you perhaps presume that the 7580 has the same power
>capability
>> >as
>> >a 4CX250B?
>>
>> Presumption or fact Rich? Yes the 250R and 7580 ( not exactly the
>same
>> tube either) have somewhat different specs than the 250B , but they
>> still have identical cathode emission.
>> So due to internal design only the R version is a bit more linear
>but
>> still suffers from the same maximums as the 250B.
>> I went thru this at length when Collins Engineers introduced the
>> AN/URC-32 to the Navy and I was part of the evaluation team ( as a
>lowly
>> tech that did all the real work !)
>>
>> 73 Carl KM1H
>>
>>
>> >>
>> >- later, Ian
>> >
>> >
>> >Rich...
>> >
>> >R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>> >
>> >
>> >--
>> >FAQ on WWW: http://www.contesting.com/ampfaq.html
>> >Submissions: amps@contesting.com
>> >Administrative requests: amps-REQUEST@contesting.com
>> >Problems: owner-amps@contesting.com
>> >Search: http://www.contesting.com/km9p/search.htm
>> >
>> >
>>
>> ___________________________________________________________________
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>> --
>> FAQ on WWW: http://www.contesting.com/ampfaq.html
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>
___________________________________________________________________
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