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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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Old 10th May 2011, 8:38 pm   #1
John G3NCN
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Smile Racal RA1772

I am looking for the circuit and layout diagrams for the RA1772 IF/AF pcb,
which has the designation PM364

Could anyone help.
Although I was responsible for the team developing all the signal path of this receiver, I didn't retain that information. I have a RA1778, not a RA1772, but the 1778, being a B-model, still had the 1772 boards, whereas the 1778 handbook documents other pcbs for this receiver.

I do hope someone could help.

John G3NCN
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Old 11th May 2011, 6:21 pm   #2
frsimen
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Default Re: Racal RA1772

John,

The Boat Anchor Manual Archive website has a good scan of the Racal 1771/1772 maintenance manual, but it is a large file (43MB).

The following link will get you what you need:

http://bama.edebris.com/download/rac...1_72maint2.pdf

Paula
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Old 13th May 2011, 7:40 am   #3
vosperd
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Default Re: Racal RA1772

Hi John
Perhaps you can tell me why my +20V psu drops out from time to time!!
I do have an original Racal manual for the 1772 so if any of the BAMA sheets are not clear I am happy to scan them for you.
Don m5aky
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Old 26th May 2011, 4:35 pm   #4
John G3NCN
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Default Re: Racal RA1772

Ref 1772 request for information:-
Very many thanks to FRSIMEN, Paula, for the website quote, and particularly to Don, M5AKY, for the data provided and the disk of information. I now have all the info 5 need, and am very grateful for your prompt responses.

John G3NCN
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Old 26th May 2011, 4:42 pm   #5
John G3NCN
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Default Re: Racal RA1772

Quote:
Originally Posted by vosperd View Post
Hi John
Perhaps you can tell me why my +20V psu drops out from time to time!!
I do have an original Racal manual for the 1772 so if any of the BAMA sheets are not clear I am happy to scan them for you.
Don m5aky
Re RA1772 query from Don VOSPERD.

Hi Don. there arose a small percentage of griplet problems with the 1772 power supply pcb. The griplet was a rivet-like insert which was used instead of plated through holes. The soldering could very occasionally be dry-joint.
Any other dry joint could be responsible, of course, but griplets are easy to spot on the pcb, and worth examining first.

Is there any particular set of circumstances which causes 20v to fail?
By the way, you are talking to a man who has not been involved for some 40+ years!!
Good Luck, Don.
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Old 2nd Aug 2011, 3:06 pm   #6
amornummi
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Default Re: Racal RA1772

My 1772 power supply failed, bridge rectifier open cct. Noticed replacement too hot so added Cu cooling sheet carefully bent to fit in.
Perhaps better way is to put long wires and bolt to chassis.
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Old 3rd Aug 2011, 8:56 am   #7
vosperd
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Default Re: Racal RA1772

Hi. John.
Only just seen your reply to my question re the 20V.
What happens is shortly after switching on sometimes the 20V drops down to about 15V. If I switch off and back on again it restores and usually stays up.
It can go for a few weeks without failing and sometimes it does it every day. I'll have a look at those feed-throughs. I remeber having problems as a service engineer with those on later valve equipment that used pcbs.
Cheers
Don m5aky.
The 1720 that drives the 1816 has now decide to give reduced power after a few years of trouble free service. Just about to start another thread...
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Old 24th Oct 2011, 12:31 pm   #8
other-way-up
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Default Re: Racal RA1772

Hi John,

A long time after your request (only just seen it), but just in case you missed it - the info you are looking for is on my 1778 Yahoo group - Chapter 12. There's a colour pcb layout and colour annotated circuit diagram on there.

For other 1778 owners, the group contains both Service Manuals and the User Guide and can be downloaded either as individual chapters or (via a link) in 2 large chunks.

David, G4IRQ


http://groups.yahoo.com/group/RA1778/
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