[Premium-Rx] RA1792 Front panel removal

[Barry Hauser]

Hi Andrew

I'm not familiar with the RA1792, but other Racal gear and other Euro built equipment have what I call for lack of a better term, "collet" knobs.

On the old RA17 (tube/valve) receiver, these were more obvious.  Instead of one or two set screws around the circumference, they have a socket for what is usually a hex/Allen wrench in the center.  When tightened clockwise, some kind of collet or drill-chuck-like mechanism clamps down and tightens on the control shaft.

As I mentioned, these were more apparent on the RA17 knobs as the chrome plated center with the hex socket was exposed and part of the trim.  More modern 70's and '80's equipment used a newer style with a trim cap concealing the works, often the same color as the knob and difficult to see.  That was, I suppose, intentional, to make the knobs solid looking.

If that's what the RA1792 has, you would need to pop off the trim caps with something sharp (without marring them) to access the allen socket in the middle. You might be able to do it with strong adhesive tape. 

Looking at online photos, I would suspect for the two small knobs, the trim caps are the same diameter as the small knobs and the seam would be along the circumference.  However, I noticed a smaller, concentric circle line on the large tuning knob.  That might be the cap for that one.

I discovered this style of knob the "hard way".  I couldn't find the set screws on a Debeg 2000, became impatient and just tried to pull off a small one.  It came apart, revealing its secrets, but not before the shaft yanked out of the dual minature pot.  Take it from this Yank -- don't yank. ;-)  

You might want to wait until you hear from someone who has hands on experience with the RA1792, but while you're waiting, look closely for the "hatches".  They are probably not just push on types.

Hope this helps,
Barry

  ----- Original Message ----- 
  From: Andrew Holme 
  To: premium-rx at ml.skirrow.org 
  Sent: Saturday, August 13, 2005 6:59 AM
  Subject: [Premium-Rx] RA1792 Front panel removal


  Hi,

  I recently purchased an original front panel for my RACAL RA1792 which has one of those blue and white Telford Electronics jobs on it.  I was wondering if anyone could give me a few pointers on the dismantling procedure?  I presume I need to disconnect the ribbon cables first, and then undo the four large retaining screws from the front?  Peering in and around it, I don't yet see how the 3 knobs will come off.  Any tips would be appreciated.

  Thanks,
  Andrew Holme.




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