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Peter, sorry I was working from the 1792 notes, in the GM Q10 obviously comes into effect on the medium speed position as well. ?I think I have three different versions of firmware .bin files if you

Aaah that makes some sense. So "Hang" AGC is only used on the long time constant it seems. I am wondering then, why it is neccessary to have R146 and Q10 at all? Maybe it was used on an earlier

Peter, Q2 OFF selects Hang mode, and I think should be ON for short and medium.? Q10 should be ON for short AGC along with U12a.? U11a should be ON for Medium, and both U11a and U12a OFF for long

Thanks Dan. There is actually nothing wrong with the AGC as far as I can tell, its just that the Hang times are wrong. I am beginning to suspect that Q2 is being turned on, thus bypassing the effect

Peter, the circuit is a bit more then those few resistors. The hang time and the decay time are /separately/ controlled by signals from the latches in 4042s U4 and U13, you need to check that they are

Hi Everyone, I have done an alignment on this receiver and it is working really well, but the only slight gripe I have is the hang AGC time constants. On the Long setting, it is incredibly long - at

Google PRC320 knobs and tell if that’s the same? De Spence G5STO Sent while portable! please excuse typos.

Guys, I’m looking for a “skirted” Racal knob similar to the one in the picture below. I think it has a 3mm (ish) spindle and is normally held by two tiny hex grub screws. Any help in tracking

Hi all, I saw on https://radiohistory.uk/RacallistB.htm that the AATU BCC540F and G can accept PWM data from the RT on a PRM 4790 and BCC39. But has anyone published the differences between these two

Many thanks Rupert - Much appreciated! Kind regards/73 Richard

Richard & Dan, I have had the RA1778 Chapter 25 paperwork scanned today and the resulting PDF is now uploaded to the Files area on this group. 73 Rupert

Good afternoon All Rupert, I think you are likely our only option to get hold of the missing pages. 2 other group members sent me really good copies of Part II after my request, just before Christmas,

Hello Dan.....and Richard, I have the RA1778 manual chapter 25 but only in paper form. If there are any parts which you'd like details of immediately then please let me know and I'll look them up for

I have a paper copy of the two volume 1778 maintenance manual which is missing the Parts List which should be Chapter 25.? Does anyone have this, as a pdf maybe?? The only on line version of Vol2 is

Good Afternoon All *RA1778 Update* Thanks to help from group members I now have 3 x fully working RA1778. This was my first experience of working on this unit and I enjoyed it more and more as I got

Time to pass this radio along, I've taken it as far as I can.?When I got it it was non-functional. I replaced the following: EPROM sockets RAM Battery (new Varta) Multiple IC's (all replaced IC's

Sounds like a tantalum capacitor to me.? If you can check all the supply voltages and find one that's zero, then unplug boards one at a time you will find the culprit soon enough.? Favorites are the

You may have a power supply problem, if you have a shorted capacitor the receiver might act this way, I have attached a file that might help. Gary E WingerdRACAL retired

Hi Arnie, Did you try running the BITE initialization? If not, just hold down the Lock button, then AM button, then release both buttons. If it finds a fault, take note of the code on the

Hello,? I'm new here.? I have and have had for many years a RA6790GM that for years has worked flawlessly.? A few weeks ago I could no longer program frequencies.? Everything lights up with Zero's