[Amps] Trying to locate amplifier

[donroden at hiwaay.net]

I have a high band ( 150 ) GE cabinet with a single cavity 4CX250B for $200.
Don W4DNR



Quoting "Fuqua, Bill L" <wlfuqu00 at uky.edu>:

> Perhaps it was a GE.
> I can't remember if it has two big dials or just one. One control  
> went to the swinging link coupling.
> But it did have a pair of forced air cooled bypassed EF Johnson  
> sockets for either 4x150 or 4cx250 tubes.
> 73
> bill wa4lav
>
> ________________________________________
> From: Glen Zook [gzook at yahoo.com]
> Sent: Sunday, December 05, 2010 11:21 AM
> To: Amps at contesting.com; Fuqua, Bill L
> Subject: Re: [Amps] Trying to locate amplifier
>
> Motorola may have built such an amplifier for the military. However,  
> for the commercial FM two-way market the Motorola lowband and  
> highband amplifiers used 8650A tubes which are the conduction cooled  
> versions of the 4CX250B. General Electric made thousands of lowband  
> and highband amplifiers using the 4CX250B that had dials similar to  
> those made by National.
>
> Motorola did make a 450 MHz amplifier using a single 4CX250B rated  
> at 100 watts output. However, with the power supply that Motorola  
> used, plus "something" in the actual physical construction, when  
> tuned for 100 watts output the amplifier would make that for less  
> than a minute and then drop back to a steady around 90 watts output.  
> I have one of those amplifiers that I tuned down to 432 MHz (tune  
> down without any problems) and bypassed the external bandpass  
> filter. Without the filter (the amplifier is still "clean") it makes  
> about 150 watts output on CW. I haven't used the amplifier for a  
> while but need to redo the bias so that I can use it for SSB as well  
> as CW. The original design is Class C for FM operation.
>
> Glen, K9STH
>
> Website: http://k9sth.com
>
>
> --- On Sun, 12/5/10, Fuqua, Bill L <wlfuqu00 at uky.edu> wrote:
>
> Many years ago (late 60's) I converted an amplifier which was a low  
> band VHF to 20 and 15 meters. It had a pair of push pull 4CX250B or  
> perhaps 4X150A tubes (no tube came with it). I parallel connected  
> the tubes, both halfs of the plate capacitor and used the whole  
> coil. I also use a dual 365pf variable to convert it to a PI  
> network. I first used it for a while with 4X150s until I came across  
> some cheap 4CX250B's.
>
> In any case I am looking for another one. It had some vernier dials  
> National on the front as well. Does anyone have an idea what this  
> was? I believe it was made for the military by Motorola.
>
>
>
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