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Old 5th Jul 2016, 7:39 pm   #1
Sean Williams
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Default Racal 1792 direct frequency input

Hi All,

Just finishing off my 1792 resurrection - suffice to say it needed much more than the couple of displays the vendor mentioned....

Anyway, I have one last problem to solve - the direct frequency input is not working.

According to the manual, depressing the frequency key should result in the display flashing, which will allow a frequency to be input - this isnt happening.

A touch out of my depth with multilegged fuses, wonder if anyone else has come across this fault?

Cheers
Sean
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Old 5th Jul 2016, 9:43 pm   #2
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Default Re: Racal 1792 direct frequency input

Fault fixed... Thanks to a helpful PM from Paula!

Sometimes the faults are the most basic ones - a dry joint on the back of the pushbutton.

Four more tantalum caps to replace, then it's covers on and install in the rack

Sean
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Old 5th Jul 2016, 11:48 pm   #3
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Default Re: Racal 1792 direct frequency input

Oooh, installing in a rack is risky. It'll wait until it's well bolted in before the next problem comes to light! Maybe a week or two on the bench might settle it in?

The 1792 is an interesting receiver but although people thought they were valuable because of the Racal badge and because they were later designs, there's a big difference from the RA1772, I found. I must get the 1792 out of the attic and give it a run, it hasn't been on for a couple of years.

Did you know that the reflective-mode rotary pulse generator disc of the main tuning can be flipped over to give an alternative tuning rate?

David
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Old 6th Jul 2016, 7:17 am   #4
Sean Williams
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Default Re: Racal 1792 direct frequency input

Not on this one David, it is a single sided disc - the receiver at hand is an ex BBC unit, without ISB or a full set of filters, nor does it have a hi stab oxco.

I guess part of the budget line was a single rate tuning disc.....

I have no doubt that it will find new and interesting ways to develop faults over the next few months, part of the reason for a wholesale replacement of all tantalum capacitors. The backup battery has been replaced recently, the memory chips have also just been replaced too, of the common faults I think this will cover most of them.

Hopefully it will behave for a while, there are some horrible looking multilegged things in there, and not all in sockets - getting the caps swapped out was bad enough!
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Old 6th Jul 2016, 9:04 am   #5
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Default Re: Racal 1792 direct frequency input

I suppose it must have saved a few pence in not waiting for it to dry, flipping it over and giving it the second silk-screen, but stocking two parts would eat into that. It's amazing how much depends on which way the wind is blowing in accountancy...

David
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