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Old 19th Feb 2018, 12:59 am   #1
briareos
Diode
 
Join Date: Feb 2018
Location: Sittingbourne, Kent, UK.
Posts: 1
Default PRC320 issues

Evening everyone.

Got myself a 320 last week, tested it out at the weekend and have two little issues, firstly I have noticed that the set rattles or something sounds like it's sliding about in there, not sure what the score with that is so will likely try and take one side off and take a look tomorrow.

Secondly, I realised that when using the dipole antenna there is a lot more noise during RX than when using the whip and gooseneck. Not sure why but with the whip I can hear distant contacts and the stations answering them, but with the dipole I can hear the closest stations but the noise drowns out the stations answering them.

Can anyone shed any light?

All the best.
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Old 20th Feb 2018, 12:04 am   #2
m3vuv51
Triode
 
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 14
Default Re: PRC320 issues

I'm not sure about the rattle, but there are certain lenths of dipole to avoid ,should be marked on the label for the tuner settings. If you have it apart check unit 5, the SMPS, there's a tant cap, think it's C1 on the 110V line goes leaky. Good idea to change that while your in there, an electrolytic will do OK. Also when you reassemble it make sure all the couplings between front and back are lined up.

73 Paul M3VUV.

Last edited by Station X; 20th Feb 2018 at 10:23 am. Reason: Readability.
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Old 20th Feb 2018, 2:17 am   #3
Martin G7MRV
Heptode
 
Join Date: May 2008
Location: Selby, North Yorkshire, UK.
Posts: 520
Default Re: PRC320 issues

There's very little spare room in an RT320, so not much space for anything to slide about, however some of the screening can screws can and do come loose.

All the electronics on the main board are attached to the front panel, the amp to the rear. So you remove the rear panel first then pull everything out from the front.

Important - with the set apart DO NOT move the turret switch! It aligns and connects with a switch on the rear panel! If you move it you'll have a hell of a job getting it back together!

Also, always turn the turret (band) switch clockwise - otherwise you risk breaking off the finger contacts in the band turret.

As for noise with a dipole, not come across that before.

Deal with the loose item first before you power the set again - you really dont want to short anything out as the most sensitive devices, the synthesiser dividers, are for all intents and purposes unobtainable, and replacement modules go for a king's ransom these days.
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Old 20th Feb 2018, 8:47 am   #4
G3VKM_Roger
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Location: Southeast Norfolk, UK.
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Default Re: PRC320 issues

Quote:
Originally Posted by briareos View Post
Secondly, I realised that when using the dipole antenna there is a lot more noise during RX than when using the whip and gooseneck. Not sure why but with the whip I can hear distant contacts and the stations answering them, but with the dipole I can hear the closest stations but the noise drowns out the stations answering them.
I'd second the comment that you should investigate the rattling/loose parts before you power up again, take the battery off to be extra safe.

As regards the noise, I'd guess the extra noise is simply because a 1/2 wave dipole has a greater capture area than a whip and so is picking up stronger signals and noise. It may also be that your local noise sources have mostly horizontal polarisation and so the dipole is picking up the noise more effectively. If you take the set out to a rural location (once you've fixed the rattle!) and try the different antennas you may find the results are somewhat diffferent.

Cheers

Roger
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Old 10th Mar 2018, 3:10 pm   #5
Racal Zonal
Triode
 
Join Date: Dec 2008
Location: Glasgow, UK.
Posts: 25
Default Re: PRC320 issues

Briareos
Back to basics re dipole have you checked the integrity of the connectors (I have had a few faults in that area), the continuity of the coax, the dipole centre and the elements of course. I am assuming here that you are using the Clansman issue items and they may well have endured a hard life in service !
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Old 10th Mar 2018, 4:54 pm   #6
ex seismic
Hexode
 
Join Date: Sep 2009
Location: Tonbridge, Kent, UK.
Posts: 308
Default Re: PRC320 issues

The sliding co-ax links have been known to be faulty or high resistance. Easy enough to take apart.

Gordon
G7KNS
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