[50mhz] Lunar Pre Amp

[jeremy-ca]

How many leads on the transistor?
If it is 4 then it is most likely a 40673 dual gate mosfet. With 3 it could 
be bipolar or FET and you would have to trace out the circuit and values to 
determine. A typical FET would be a J-310/U-310.

Typical circuits would be in the ARRL Handbook roughly corresponding to the 
era of the preamp.

Ive repaired many a brick preamp without a schematic using just a few common 
devices. The designs were far from optimum anyway and there is lots of 
leeway in substitution especially at 6M.

Carl
KM1H


----- Original Message ----- 
From: "Ray Keefe" <KC2GMN at VERIZON.NET>
To: <50mhz at mailman.qth.net>
Sent: Friday, August 24, 2007 7:05 AM
Subject: [50mhz] Lunar Pre Amp


>I haven't been able to locate any info on the usual sites about a Lunar 
>PAI50B 6 meter receive preamp. Mine just went dead recently after a 
>lightening strike near my house recently. (At the same time I also lost 3 
>of the 4 ports in my dsl/router and 4 of the 8 in my other network hub, 
>along with a tv antenna amp).
>
> I opened it up and checked the only transistor in it and found 12vdc on 
> one lead and zip on the others, after unsoldering it (it's mounted upside 
> down through the pc board) to read the numbers on it to find a 
> replacement. It's house numbered and no cross reference. I did find one 
> cooked resistor in the rf sense ckt that I used SWAG to find the value and 
> replace it. Didn't make any difference, still deaf on receive and the T/R 
> relay still works.
>
> Does anybody have a schematic for this unit, since it appears that Lunar 
> has gone bye bye a long time ago.
>
> Thanks
> Ray
> KC2GMN
>
>
> Moderator: Ray Brown, KB0STN
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