[Amps] Old Moto RF Decks

[Glen Zook via Amps]

The 8560A is basically a conduction cooled 4CX250B.  The Eimac specification sheet on the 8560A states that the characteristics are similar to, but not exactly the same, as the 4CX250B.  The differences are that the 8560A has a Cin of 16.5 pf whereas the 4CX250B had a Cin of 15.7 pf and the 8560A has a Cout of 4.6 pf and the 4CX250B has a Cout of 4.5 pf.
Otherwise, the "typical" operating conditions are the same for both tubes.
The main thing with the 8560A is that the heatsink plays a VERY important part as to how much power can be run.
I have a fair number of 8560A tubes left over from my two-way radio days.  I just don't have the heatsinks!
Glen, K9STH

Website: http://k9sth.net
      From: Carl <km1h at jeremy.qozzy.com>
 To: John Kinney <J.Kinney at freescale.com>; amps at contesting.com 
 Sent: Monday, December 1, 2014 2:43 PM
 Subject: Re: [Amps] Old Moto RF Decks
   
SSB IMD goes up rapidly above 300W per tube even with simplistic screen 
regulation. Be a good neighbor on the bands with those rather aged and 
obsolete designs (1947) that predate widespread SSB use.

Collins rated their 1960 AN/URC-32 at 500W with a pair of lower IMD 
4CX250R's at 2000V while Eimac rated them to 2500V with poor IMD specs. 
Those transceivers, at 6' tall, ran fine without clobbering other close 
channel USN users.