[MRCA] PRC-127

[B. Smith]

I think I would calibrate the time base in the counter first. If it is 
10 Mc you can easily beat it against WWV and get it down to a 2 or 3 
cycles-  - -, just listen for the wump wump wummmmp .  :-)
Then immediately take your readings.

Z


On 7/30/2013 9:29 AM, Robert Newberry wrote:
>
> My freq counter says at 136.000 programmed. Reads 136.00199. 
> Programmed 160.0000. Reads 160.00225.
>
> It is also off consistently by approximately that much on all channels.
>
> Apparare Scientior
> Paratus Communicare
> -N1XBM
>
> On Jul 30, 2013 8:42 AM, "Ray Fantini" <RAFANTINI at salisbury.edu 
> <mailto:RAFANTINI at salisbury.edu>> wrote:
>
>     Important after thought, if the radio is on channel on any channel
>     the reference oscillator is correct! Check the error on the lowest
>     programmable channel around 136 MHz and the highest channel 160
>     MHz and although the percentage of error may be different if there
>     is no error on some channels and error on others it's not a
>     reference problem, in that case you have a divider problem and
>     throw the radio away! But if you see a consistent error that
>     increases with frequency like your describing would assume that
>     your reference oscillator is a little off.
>     Ray F
>
>     -----Original Message-----
>     From: mrca-bounces at mailman.qth.net
>     <mailto:mrca-bounces at mailman.qth.net>
>     [mailto:mrca-bounces at mailman.qth.net
>     <mailto:mrca-bounces at mailman.qth.net>] On Behalf Of Ray Fantini
>     Sent: Tuesday, July 30, 2013 8:30 AM
>     To: Robert N. Newberry; mrca at mailman.qth.net
>     <mailto:mrca at mailman.qth.net>
>     Subject: Re: [MRCA] PRC-127
>
>     It's pure speculation on my part not having worked on a 127 before
>     but most synthesized radios built around that time are designed
>     around an internal fixed reference oscillator and a programmable
>     divider chain that controls a PLL. Being that the radio will
>     channel and if it accepts program changes would assume that the
>     divider chain and PLL are all working and it may just be that your
>     reference oscillator is not on frequency. Be cautious because a
>     small change in the reference oscillator will result in a big
>     change in operating frequency. Al lot of stuff produced back in
>     the seventies and eighties worked with reference oscillators in
>     the 5 or 10 MHz range. Newer radios used sealed reference
>     oscillators but things that old often had discreet component
>     oscillators. But if you can enter new channels and the radio is
>     somewhat on channel the synthesizer is working so don't mess with
>     things like the VCO or PLL system because that will only get you
>     in trouble, good luck.
>     Ray F
>
>     -----Original Message-----
>     From: mrca-bounces at mailman.qth.net
>     <mailto:mrca-bounces at mailman.qth.net>
>     [mailto:mrca-bounces at mailman.qth.net
>     <mailto:mrca-bounces at mailman.qth.net>] On Behalf Of Robert N. Newberry
>     Sent: Monday, July 29, 2013 10:07 PM
>     To: mrca at mailman.qth.net <mailto:mrca at mailman.qth.net>
>     Subject: Re: [MRCA] PRC-127
>
>     I should of specified by high in frequency I mean frequency error.
>
>
>
>     On 7/29/2013 10:08 PM, fred anderson wrote:
>     > There is an old DOS program call ham n eggs which reprogrammed
>     the PRC
>     > 127 to the Ham Band
>     >
>     >
>     >
>     > Fred KB4DMQ
>     >
>     >
>     >
>     > From: mrca-bounces at mailman.qth.net
>     <mailto:mrca-bounces at mailman.qth.net>
>     > [mailto:mrca-bounces at mailman.qth.net
>     <mailto:mrca-bounces at mailman.qth.net>] On Behalf Of Robert Newberry
>     > Sent: Monday, July 29, 2013 4:18 PM
>     > To: mrca at mailman.qth.net <mailto:mrca at mailman.qth.net>
>     > Subject: [MRCA] PRC-127
>     >
>     >
>     >
>     > I have a PRC-127 that is a little high in frequency. I've
>     skimmed thru
>     > TM
>     > 11-5820-1048-24 but I didn't see anything about adjustment.
>     >
>     > Anyone know where to find adjustment info?
>     >
>     > Apparare Scientior
>     > Paratus Communicare
>     > -N1XBM
>     >
>     >
>
>
>
>
>
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