[Repeater-Builder] Help with N1274A VHF amplifier please

[Albert]

I have very cheaply acquired a Motorola N1274A amplifier and would like to use 
it on 2 meters. 

My first question, is, since this amplifier was originally designed for 
150-174MHz do I need to do any retuning. I assume the answer would be yes. On 
the board, on the far left and the far right I see two components that appear 
to be tuning capacitors. They are marked Johanson 9612. (Looking them up on the 
net confirmed they were tuning caps) Are these what I need to adjust? If so, 
what is the procedure? Tune for max power? Min SWR? Any assistance would be 
appreciated. Also, what tool is used for this? I kind of looks like a tiny hex 
head, but I haven't looked at it under a magnifier yet.

Secondly, I was wondering if anyone has a schematic for the amplifier. I looked 
on the net but turned up nothing. There is one component inside the amplifier 
that appears what used to be a capacitor. It obviously suffered a 
catastrophic failure and the magic smoke came out quite rapidly. It is located 
on the board next to a large 1 ohm power resistor. I obviously need to replace 
this component and could possibly need to replace others. Again, any schematic 
or parts list info anyone could share with me would be greatly appreciated.

Thanks
Albert

RE: [Repeater-Builder] Help with N1274A VHF amplifier please

[Eric Lemmon]

Albert,

Yes, you must tune the amplifier for the narrow range of frequencies that
you will be using.  The N1274A amplifier was used with MT500 and MX300
Converta-Com Consoles to boost the output of the Handie-Talkie in mobile
service.  The unit has a sensor to detect the transmit signal and switch the
amplifier into the circuit,  The manual which covers this specific amplifier
is 6881020C90- which, unfortunately, is NLA from Motorola Parts.

73, Eric Lemmon WB6FLY
 

-Original Message-
From: Repeater-Builder@yahoogroups.com
[mailto:repeater-buil...@yahoogroups.com] On Behalf Of Albert
Sent: Tuesday, March 10, 2009 11:04 PM
To: Repeater-Builder@yahoogroups.com
Subject: [Repeater-Builder] Help with N1274A VHF amplifier please

I have very cheaply acquired a Motorola N1274A amplifier and would like to
use it on 2 meters. 

My first question, is, since this amplifier was originally designed for
150-174MHz do I need to do any retuning. I assume the answer would be yes.
On the board, on the far left and the far right I see two components that
appear to be tuning capacitors. They are marked Johanson 9612. (Looking them
up on the net confirmed they were tuning caps) Are these what I need to
adjust? If so, what is the procedure? Tune for max power? Min SWR? Any
assistance would be appreciated. Also, what tool is used for this? I kind of
looks like a tiny hex head, but I haven't looked at it under a magnifier
yet.

Secondly, I was wondering if anyone has a schematic for the amplifier. I
looked on the net but turned up nothing. There is one component inside the
amplifier that appears what used to be a capacitor. It obviously suffered
a catastrophic failure and the magic smoke came out quite rapidly. It is
located on the board next to a large 1 ohm power resistor. I obviously need
to replace this component and could possibly need to replace others. Again,
any schematic or parts list info anyone could share with me would be greatly
appreciated.

Thanks
Albert