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[Amps] Who sells 3CPX-800A7's besides RF parts ??

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Subject: [Amps] Who sells 3CPX-800A7's besides RF parts ??
From: "Jim Thomson" <>
Date: Wed, 13 Jul 2011 08:01:16 -0700
List-post: <">>
Date: Wed, 13 Jul 2011 13:27:35 +0100
From: "Dr. David Kirkby" <>
Subject: Re: [Amps] Who sells  3CPX-800A7's  besides RF parts ??

On 07/13/11 11:01 AM, Jim Thomson wrote:
>   I use to know this..but lost the info.    There was a couple of co's 
> somewhere in the eastern usa that had... 'good' prices on  3CPX-800A7's.
> Tnx... Jim  VE7RF

Do you need the pulsed version (P in the part number)? The 3CX800A7 is far more 
common than the 3CPX800A7. Without looking at the data sheets, I've no idea how 
similar they are.

There are tons of 3CX800A7s on eBay.

##  An associate of mine wanted the pulse rated version,and NOT the more common 

The pulsed version was good for something  like 3500 vdc.   Years ago, eimac  
sent out a bulletin, and advised broadcaster's etc  to use the
pulse version for these low power  750/1500  output  1 and 2  tube   FM  
broadcast TX's.    The line v  in some parts of the world is not good, plus
toss in transients/spikes,  gen sets at times etc... and way too many failures. 
 The pulse rated versions  drop right in.. and now u have some  V
head room = no more failures.  

I think my ham friend wanted some extra v headroom, cuz perhaps his B+  supply 
was a bit on the higher side for the standard version..and  he doesn't 
want to push his luck.  Some other folks  have plugged the pulse version into 
their Alpha  87-A's..and they run just fine..albeit  with abt 10 ma  more grid
current, that's  it. 

I don't think the pulsed version was that much more $$  either.  In the case of 
broadcaster's, that's  nickle and dime stuff  anyway.  They just want
reliability.    BTW, our  fed govt has a forestry  dept here in town, where 
they use a 3CX-3000A7  to generate  RF at 70 mhz... then radiate it into plants
etc, that have been subjected to various gas's.. [think they used argon, among 
other's]... then  the result is it breaks it into the colour  spectrum  for a 
given species.   Some kinda
spectrograph if I remember correctly.   The kicker was, they used a 
5000 VA  rated eq of a big Sola  constant v xfmr.. to provide regulated  AC  to 
the plate xfmr of the b+ supply.      That was a new one on me. 
[  Eimac  3x3 tube  got replaced with a SS  PA module.]  

Impractical   for broadcasters.   The pulse version is cheaper solution. 

later...... Jim  VE7RF  

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