[Amps] Trying to locate amplifier

[Pete Lancashire]

a friend that does cell site service told me last year that one site
owner who leases his
half dozen mountain tops in the Seattle area gave notice to one paging
company that if
they did not come get their 'junk' he would have it shipped to them
and charge them for
doing it. I was told on one site a month later he saw the paging
equipment in a pile outside in
the rain.

-pete

On Mon, Dec 6, 2010 at 6:47 AM, Sam Carpenter
<sam at owenscommunication.com> wrote:
> Moto did make some very robust VHF tube amps. Most that I have seen come
> through the shop over the years have been with a Moto marked conduction
> cooled tubes that strap to a very large heat sink in the back. The tubes
> looked like 8873 series tubes. The tank was VERY robust and I have seen
> people use the RF deck with 8877 tubes. I think these were quarter K
> amplifiers but would do much more. I will look around the service manual
> archives we have in the shop and see if I can find models and spec's for
> you. There were also tube HF amps made. I think they were rated at a K.
> Power supply would not do too much more. There is a bit of data on the web
> if you google around. I think I found things using Motorola HF amplifier. I
> think that is where I saw the conversions as well.
>
> There are tons of paging transmitters sitting idle right now. When I go out
> to high profile sites they are just sitting there unplugged. I think the
> market fell out so fast that they never picked them up or hauled any away. I
> think most of the site owners would gladly have someone haul them away. Most
> of the tube units were back-up for the newer glenayre solid state units.
> They are pretty sweet too. I think though that the VHF amps were run in
> Class C. I think that the HF amplifier started with the letters THD, or THE.
> That may help refine the search. I will save this and let you know if I run
> across anything.
>
> Sam N9FUT
>
>
> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of donroden at hiwaay.net
> Sent: Monday, December 06, 2010 9:15 AM
> To: amps at contesting.com
> Subject: Re: [Amps] Trying to locate amplifier
>
> 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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