[Milsurplus] PRC-47 on LSB Help

Wed, 12 Nov 2003 18:12:01 -0500

I modified my PRC-47 with the 618T USB filter (due to frequency inversion
the original filter in the PRC-47 is LSB) to get LSB output. The 618T filter
is the same series of the Collins filters, except it's just the opposite
sideband. Even the pins are the same as the original PRC-47 filter. I didn't
have to tweak anything to get good audio and full output.
If you want to keep the USB, you'll have to squeeze in the new filter and
not just swap it, and switch between them with a reed relay. Usually the
dial light switch is used for this, if you don't want to drill an extra hole
in the panel for a new switch.

I found the greatest problem in the PRC-47's is the lousy germanium chopper
transistors in the 24 VDC to 115 VAC 400 Hz supply. Both transceivers I got
blew them as soon as I turned them on. The germanium junctions don't age
well and deteriorate.  Replacement transistors are costly, so the solution
is to put cheap silicon switching transistors in the circuit. Did anyone
experience the same problem?

73, Meir WF2U

-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Barnes Norman
Sent: Wednesday, November 12, 2003 3:06 PM
To: [email protected]
Subject: [Milsurplus] PRC-47 on LSB Help

I have acquired the PRC-47 transceiver and would like
to modify for LSB as well as having USB still usable.
I have the LSB filter from a 618T transceiver (I was
told that this could be used for conversion to LSB)
Has anyone performed this mod and is there a source of
information for doing this?  Any help would be
appreciated.

73, Norman