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UHF Amplifier 2C39A tube
Posted: Sat Nov 29, 2014 1:05 am
by ka1nvz
Is anyone familiar with a Motorola single ended amplifier with a 2C39A tube in it? The unit I have is rack mounted and looks commercially made probably early 1960’s. I assume it’s some kind of RF amplifier for UHF service.
Re: UHF Amplifier 2C39A tube
Posted: Sat Nov 29, 2014 7:16 am
by Jim202
ka1nvz wrote:Is anyone familiar with a Motorola single ended amplifier with a 2C39A tube in it? The unit I have is rack mounted and looks commercially made probably early 1960’s. I assume it’s some kind of RF amplifier for UHF service.
If your looking for some information on this unit, it would help if you provided the model number that should be on a name tag, someplace on the unit or maybe just an ink stamped number.
From past experience with the 2C39 tubes, they generally were used in UHF amps. Some used a VHF input and multiplied 3 times to the UHF output frequencies.
Jim
Re: UHF Amplifier 2C39A tube
Posted: Sat Nov 29, 2014 5:58 pm
by ka1nvz
This is what is stamped on the chassis on the outside, TU-577 and the inside is 63-854629.
Re: UHF Amplifier 2C39A tube
Posted: Sat Nov 29, 2014 7:23 pm
by wb0qqk
I'm going back into my memory banks about 40 years, but I did have some experience with
Motorola UHF 'A' Series strips. The unit you have was probably made in the late 50's.
I'm not aware that Motorola made a separate UHF PA that used a 2C39 tube. The only
version(s) I ever saw was a complete transmitter strip that had a crystal oven, a 12AT7
oscillator, a 6CB6 modulator, another 6CB6 as the 1st doubler, a 5763 2nd doubler and
a 6146 3rd doubler.
As I recall, they actually used a matched pair of ML2C39WA or 197T119A01 ceramic tubes.
One was a tripler-driver and the other was the power amp which would put out a whopping
18 to 20 watts.
In repeater service (Model B44AAY), forced air cooling was a necessity and was provided by
a TK192 blower kit that consisted of a small squirrel cage and a motor that attached to the
chassis adjacent to the PA. They wore out frequently which resulted in PA failures. When
the kits were no longer available (NLA) we replaced them with a muffin fan and fashioned
a duct that directed air into the PA.
Re: UHF Amplifier 2C39A tube
Posted: Wed Dec 31, 2014 11:28 am
by Tron
WOW, this brings back memories. Had several Twin V UHF mobiles that used on the CB UHF freqs and had built up a base station with these too. Its amazing they worked as well as they did, all things considered. Got out ~25 miles bse/mobile with them on simplex. There was a high stability transmit TXCO kit that could be installed by plugging into the tx xtal socket. Used to have the green service manual for these.
Tron
Re: UHF Amplifier 2C39A tube
Posted: Wed Dec 31, 2014 10:08 pm
by Satelite
Hello:
Yeah WOW I too remember the Twin V mobile.
Boy we did go back in time .
Id feel better if youd said the mocom 10 which again I saw the insides of them to.
Low banders here though normaly 37.10 on police and a business that was on 35.180
Still have the base antennae in one pc still usable set up for the 35.180 freq.
Whoofda im getting old.
Satelite
Re: UHF Amplifier 2C39A tube
Posted: Thu Jan 01, 2015 8:50 am
by Tron
I've seen my share of Mocom 10's too in local bus companies. I am old!

Had a few 80-Ds ( low band ) to work on too. Customer swore they worked better than the Motracs they had.
Re: UHF Amplifier 2C39A tube
Posted: Wed Feb 18, 2015 7:45 am
by RTESTP25
The motorola t-44 radios in the 1960 has amp with 2c39 tube that was a receiver pre-amp.
Re: UHF Amplifier 2C39A tube
Posted: Fri Feb 20, 2015 7:23 am
by Tron
I built up a pre-amp using this tube. IIRC, used their final output module from a scrapped radio. Worked great.