[Milsurplus] [MRCA] AN/PRC-70

[Mike Feher]

Hi Ray - I have 4 PRC-70s. Two are fine and the other two have issues. I
also have the matching 100 watt external PA. Regardless, I do have a full
manual, but it is down in the basement. I hardly ever venture down there any
more as my knees do not like stairs, HI. However, I will see if I can build
up my courage to go down there and find it. 73 - Mike 

 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

848-245-9115

 

From: mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> On Behalf
Of Ray Fantini
Sent: Monday, November 21, 2022 10:21 AM
To: MMRCG at groups.io; MRCA <mrca at mailman.qth.net>; milsurplus at mailman
<milsurplus at mailman.qth.net>
Subject: [MRCA] AN/PRC-70

 

Ok, so this is the first time I have had the opportunity to work on a PRC-70
Was raised on all the horror stories and the like about the bad things that
happen if you run at reduced battery voltage and the like but this set
belongs to a friend and he tells me that the radio was working when he
bought it but was dead when he received it.

The radio, battery box and power supply came with a bunch of W7FG manuals
and that's my first problem. The operator's manual is cute and has lots of
pictures but no technical information, couple of the manuals are on the
external power supply and the Direct Support & Gen Maintenance Manual has
issues.

I suspect that the radio has a problem with its DC to DC converter assembly
not starting, think they call it a Flyback regulator 1A1A2, according to the
book that works with the 1A1A3 Trigger and 30 V Regulator and they feed the
1A1A4 10 V regulator and the 1A1A5 5 V regulator.

The issue I have is that the DTM 11-5820 -553-34 Technical Manual images and
module layout have very little to do with the RT-1133/PRC-70 that I am
looking at. The manual is for a PRC-70, no questions about that but not this
PRC-70 unless there is something that I am missing? Where the manual says
the flyback, trigger and regulator boards are located is completely
different. In this radio the relay card, and what appears to be the power
supply and regulator card (just one) are all located in the back of the
radio and not on the right-side front?

Dose this radio fold out or have some other level that I am not seeing? At
this time all I know is that when the radio is turned on and in receive
there is no sign of life beyond a small click that you can hear when turning
the power on and if I turn the dial light on it lights up so power is
getting to the radio.

The other problem I have is that the manual shows what all the modules and
test point along with a overall schematic for the motherboard there is
nothing about what's on each module themselves. Any ideas where I can obtain
a set of schematics for this radio?

Once again this is a Cincinnati Electronics RT-1133/PRC-70 MFR-80045

 

Ray F/KA3EKH

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