The RCA CERMALOX tube 8122 was used in the HALLICRAFTERS SR 2000 and the
NATIONAL NCL 2000 ( two of them ) and in a number of marine transmitters.
LA8AK reported years ago many difficulties with the 81221 at LYNGBY RADIO
Denmark. The same tube tube, without the cooler is the 8072 used in the
SIGNAL ONE. There is also a third version, the 8121, which is very rare and
cooled across the tube. Due to the unique grid cup construction those tubes
can take 100 MA grid current. The screen grid should certainly take even
more because it is larger and has contact with the outside world through
its screen grid ring. The tubes are nowadays made by BURLE and EIMAC has
made a ruggedized version of them. Also I have seen a quick heat version of
the 8072 made by RCA.
Hi mu triode connected maybe a cheap replacement for the 8874 or 8875? Maybe
happy DENTRON owners? One has maybe to manufacture a cooler for the 8072.
Can anybody check if this is possible? I am planning to build a supercathode
version described in - was it in 73 or CQ magazines?
Hej de Hans / SM5KI
----------
>Från: "Jim" <jdc@ieway.com>
>Till: "Thomas Cook" <tacookfam@exotrope.net>, "William L. Fuqua III"
<wlfuqu00@pop.uky.edu>
>Kopia: "AMPS" <amps@contesting.com>
>Ämne: Re: [AMPS] VHF and 8122
>Datum: fre 8 okt 1999 05.44
>
>
>RCA used the 8122 in a 450 MHz commercial 250 watt transmitter..It was in
>their "Super Basephone" series....
>
>RCA GE and Motorola used the 8072/4657, (the same exact tube without the
>anode cooler fins) in their base, mobile and repeater stations.
>The tube was held in place with a heat sink that surrounded the tube and
>then was fastened to a larger heat sink with a mica wafer for high voltage
>insulation......
>
>
>
>They really were a great tube!
>
>Hope this helps...
>
>
>Jim W7RY
>
>
>-----Original Message-----
>From: Thomas Cook <tacookfam@exotrope.net>
>To: William L. Fuqua III <wlfuqu00@pop.uky.edu>
>Cc: AMPS <amps@contesting.com>
To: <amps@contesting.com>
>Date: Thursday, October 07, 1999 10:42 AM
>Subject: Re: [AMPS] VHF and 8122
>
>
>>
>>There was a series of articles in QEX some time ago that addressed the
>>usability of various tubes on V/UHF. The 8122, I believe has some drift
>>problems at 432; not sure about lower freqs. Perhaps someone else can
>>shed some concrete info on this. They were used quite successfully in
>>the old National NCL2000 HF amp; I used to drive one with an old Central
>>Electronics 10B phasing exciter back about 1969 - worked fine.
>>
>>73, Tom - WA2BPE
>>
>>"William L. Fuqua III" wrote:
>>>
>>> Well it seems ashame to sell the dozen 8122's in this amplifier
>>> and discard the VHF bypassed sockets and teflon chimneys.
>>> Maybe the thing to do is to make a few VHF amplifiers.
>>> Has anyone had experience with the 8122 in VHF amplifiers for
>>> 144 and 440 MHz?
>>> On the other hand do I have time for more projects. I have
>>> not seen my work bench for some time. It it is under a pile of
>>> parts in the basement. HI HI......
>>>
>>> 73
>>> Bill wa4lav
>>>
>>> William L. Fuqua III P.E. E-mail WLFUQU00@POP.UKY.EDU Phone (606)
>257-4155
>>> Department of Physics and Astronomy CP-177 Chem. Phys. Bldg.
>>> University of Kentucky , Lexington, Ky 40506-0055
>>>
>>>
>>>
>>> --
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>>
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>>
>
>
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