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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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7th Nov 2018, 6:37 pm | #1 |
Retired Dormant Member
Join Date: Nov 2018
Location: Paris, France
Posts: 1
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Clansman PRC320 unstable.
Hello.
I am new to this forum. I just got 2 weeks ago a PRC320 for the one i already install the LSB kit which fonction correctly but i discovered a problem the rig is already instable in frequency, does the lsb kit must be shielded or the problem coming from the slave oscilator or maybe the synthetiser ? any suggestions will be appriciated. my best regards Reilly Patrick F6FCM PS: test has been made with regulated 28v power supply same symptom with battery |
7th Nov 2018, 7:38 pm | #2 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,996
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Re: Clansman PRC320 unstable.
There are 2 common causes of instability [frequency-scintillation] of the PRC320.
One: the contacts on the rotating band-selector can become tarnished. Rotate the band-selector knob clockwise through several complete rotations and it can help remove the tarnish. Two: There are several tantalum capacitiors in "module 5" the power-supply. These are rated at 130V and are operated at 125V. They become leaky and cause the +120V synthesizer/VCO control-voltage to wobble slightly. Replace them with modern 160V electrolytics. See here: http://www.vmarsmanuals.co.uk/newsle.../prc320psu.pdf |
8th Nov 2018, 4:31 am | #3 |
Banned
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
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Re: Clansman PRC320 unstable.
theres also tants in the synth go leaky,and you dont need to shield the lsb carrier insertion oscillator.
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8th Nov 2018, 4:34 am | #4 |
Banned
Join Date: Feb 2018
Location: Horncastle, Lincolnshire, UK.
Posts: 203
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Re: Clansman PRC320 unstable.
its a small world the article you linked in vmars was written by a personal friend of mine colin g4ddi,theres not a lot he doesent know about all things clansman.
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8th Nov 2018, 9:34 am | #5 |
Heptode
Join Date: Sep 2009
Location: Tonbridge, Kent, UK.
Posts: 686
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Re: Clansman PRC320 unstable.
Rotate the band-selector knob clockwise..........
And only turn it clockwise if you want to preserve the contacts in it. gmb |