[MRCG] who's up for a repair challenge? prc-47

[Tim]

Hi Jason - PRC-47 adventures!
I have one and it is pretty good - I use it in the field a lot and when it
works, it's great.  Once you get the bugs out they are quite reliable...I
think the TX audio sounds good with an H-33 handset, the receiver - well,
its an SSB combat radio.......  If you tinker with the audio gain and AGC
adjustments (deviate from the manual settings) they can sound OK.  The RX
has lots of sensitivity...but it can overload quickly..
As you probably already know they can be tough to work on due to their
packaging, shielding and need for extender cables in many cases.  The good
news is they have lots of DC and signal test points  Absent those extenders
it can be difficult !  But it can be done.
Dumb question about your problem:  Is the PS 400 cps oscillator running
during transmit?  Putting a scope on the TX driver test point will tell you
a lot....Hint:  If the PS oscillator is running I'd recommend doing the
initial TX troubleshooting in the LO power mode but substitute a 5 Amp fuse
(vs. 20 Amp)  in the front panel 24V circuit as a starting point.  Might
save your transistors...
Here is some other thoughts of mine on PRC-47 adventures....
http://www.n6cc.com/the-prc-47-hf-ssbcw-transceiver
Since your RX is working, leave it on 11175 KC and listen for the USAF HF
Global Communications System channel traffic while you are doing something
else.

Good luck - it's worth the effort.
Tim
N6CC


On Wed, Jun 5, 2013 at 9:53 AM, Jason W6IEE <w6iee.73 at gmail.com> wrote:

> I'm having second thoughts on my plan to "give up" on my prc 47, the one
> that I've been trying to sell for a few months. Would be much more fun to
> be able to use the stupid thing. ;)
>
> Who in this group is well-versed at repairing this little monster and might
> be interested in taking on another?
>
> Basically, my unit receives fine, but has never transmitted properly,
> barely any modulation, and next to no power output. Swapping modulator
> modules from my parts unit didn't help. I also just noticed that I get
> absolutely no meter deflection when putting the switch into the "tune"
> position.
>
> I'd be glad to trade my parts unit, and the extra "LSB" mechanical filter
> (which I don't think I'd ever use) for the effort, and I'd certainly be
> open to further discussions for same.
>
> I have too many other projects, and the radio is just a tad too complicated
> to dive into it myself.
>
> Thanks,
> Jason W6IEE
>
> --
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