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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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28th Sep 2006, 11:28 pm | #1 |
Retired Dormant Member
Join Date: Sep 2006
Location: Kent
Posts: 3
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Racal RA1776 Help!
I have recently obtained an RA1776 which is works fine below 18MHz. When I select 18MHz and above, the "Out of Lock" LED illuminates and the radio goes deaf!
I've not even had the case off yet, any clues as to where I should start? Any help would be appreciated |
28th Sep 2006, 11:34 pm | #2 |
Dekatron
Join Date: Feb 2005
Location: St.Ippolyts, Hitchin, Hertfordshire QRA IO91UW
Posts: 3,518
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Re: Racal RA1776 Help!
First stop - get a manual - you will certainly need it!
Second, get real familiar with Phase locked Loop circuitry. Then hope that the fault is supply rail related, and not in the custom ICs that Racal love so much! Once you have some info come back to us, and we can have a go! What level of experience do you hold - it will make a difference in the sort of replies you get! Welcome to the Forum Cheers Sean
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29th Sep 2006, 8:57 pm | #3 |
Retired Dormant Member
Join Date: Sep 2006
Location: Kent
Posts: 3
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Re: Racal RA1776 Help!
I have the manual!
I have a reasonable radio based background with cough-cough years of fault finding, I just cannot get my head around the PLL circuitry! Racal had some great ideas but wow!, complex! I need to get the case off and probe around. I have a gut feeling there are 3 oscillators and a changeover happens at 18 MHz! Hopfully someone may have an idea! |