[MRCA] Field opps and frequencies

[Anthony Clare]

Ray,

The clarifier function and the calibrate function share the same knob, but are
two separate capacitors. You perform the calibrate function by pushing in the
knob and turning until you get zero beat on the calibrate tone. You would do
this anytime you make a frequency change.

The clarifier function is a separate capacitor that is switched in or out of
circuit between receive and transmit. Removing the wire that I mentioned
earlier just forces the clarifier cap to stay active all of the time. I
believe that some realignment is necessary after the mod. If you did the
alignment previously, you should have no problem with it. If you recall in the
alignment, there is a point where you have to activate the relay to perform an
alignment step. This is where that comes into play. I cannot remember exactly
what I did now, but I could do it if the radio was in front of me.

n3kcb
------ Original Message ------
Received: Mon, 22 Jul 2024 10:13:54 AM EDT
From: Ray Fantini <RAFANTINI at salisbury.edu>
To: Anthony Clare <n3kcb at usa.net>, "MMRCG at groups.io" <MMRCG at groups.io>,
"mrca at mailman.qth.net" <mrca at mailman.qth.net>Cc: "milsurplus at mailman.qth.net"
<milsurplus at mailman.qth.net>
Subject: RE: [MRCA] Field opps and frequencies

I need to go back and look at the manual, the clarifier has two functions. One
where you can turn it to copy SSB on receive and some weird thing where you
push it in and zero beat it or something? I don't know. On Saturday when N2MS
told me I was off channel I turned it a quarter turn and that appeared to
help. Don't know if you are supposed to push in and zero beat it first and
then use it to adjust the received frequency or what. Have a bad habit of just
picking up radios and playing with them and not reading the manual first, and
then learning that on some radios if you don't do things by the book you're in
for trouble.
Maybe I should  just get one of those G90 things that are idiot proof? Maybe
not, don't think I can live with myself with a radio that built in China and
would suspect is impossible to work on. Sorry if I offended anyone running
them, would think that it's a fine radio but just my thing.

Ray F/KA3EKH


-----Original Message-----
From: Anthony Clare <n3kcb at usa.net> 
Sent: Monday, July 22, 2024 9:51 AM

Ray,

There is a wire that needs to be disconnected internally to allow the
clarifier control to affect both receive and transmit on the PRC-74. It's easy
to do. I can get you a photo of that when I get home.

n3kcb

------ Original Message ------
Received: Mon, 22 Jul 2024 09:23:14 AM EDT
From: Ray Fantini via MRCA <mrca at mailman.qth.net>
To: "MMRCG at groups.io" <MMRCG at groups.io>, "mrca at mailman.qth.net"
<mrca at mailman.qth.net>Cc: "milsurplus at mailman.qth.net"
<milsurplus at mailman.qth.net>
Subject: [MRCA] Field opps and frequencies

As stated before was up in PA Hamburg, or Port Clinton or whatever it's called
with the PRC-74.
Not a lot of experience with that radio and still learning the finer points
like how to set the frequency but did have some fun.  At ten local that
morning attempted to operate on 7296 for the MMRCG USB net but no love there.
Did hear WF2U and a couple other stations but they never did hear me. I was
running the whip on the radio so imagine that's not that efficient of forty.
Did hang the dipole antenna for the MRCA M&S net at noon. I remember Joe
telling me about doing NVIS with low dipoles so I ran the one leg of the
antenna from the radio to a tree maybe six or so feet off the ground with the
other leg just running acrost the parking lot. The antenna loaded without
issue and did discover that the length of the "cold" side of the dipole makes
a difference between getting a good match in transmit but did not hear any
difference between if it was attached on receive.
Dean, KK1K as NCS had a big signal, N2MS running portable was also solid on
the low dipole and was able to copy most stations without issue. The PRC-74
has a good receiver, did find that it was off frequency and did adjust but
think I need to review the procedures for calibration in the field. Did pull
that radio apart and do a alignment of all the osculators that set the
different frequencies a couple months back but the internal field calibration
and clarifier are still a mystery to me.
Before M&S net did hear W2HX and K3TZJ but they never heard me, maybe because
I was off frequency or whatever because I was not able to set the frequency
until I started talking with N2MS just before the net.
Think the issue is that you set the frequency on the radio and then use the
clarifier knob and that's gets good copy on the receiver but the transmitter
is still somewhere else, use to modern radios where you just crank in the
channel and go.
Also have to wonder on the feeder cable that came with the radio that allows
you to set the antenna up in the field that appears to be some sort of ladder
line and maybe if both ends of the antenna were up in the air it would have
worked better. Do have to say I like the little hand reels that have the
calibration charts on them for laying out the dipole but have to wonder what
the significance of the numbers are printed on the chart and line, it's not
frequency or anything like that. One thing about this PRC-74 is when I got it
had a huge bag of stuff that came with it, antennas, CW keys, adapters and all
sorts of stuff to play with in the field. For fun I did try running the whip
antenna on sixty meters and had maybe a half to a third of reception level
with the stick. And as far as power goes have been using an 8 AH gel cell,
although it's kind of small for that radio it fits into the battery box well.
As far as frequencies go, will remind everyone that MMRCG has been running a
Saturday net on 7296 USB for years now at ten eastern, I have also had issues
with 5357 just not making it up north. Can work people like Ron K3TZJ or N2MS
but WB2JWU as NCS for M&S has been poor copy at my QTH for almost a year now.

Ray F/KA3EKH




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