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3pinplug
12-10-2021, 02:05 PM
Hi all
Does anyone know how to set the bias on this radio at all. I know there is a link wire you cut but then i have VR13 and VR14 to set but dont know how to get a reading in ma for each VR.
Thanks
Mark

Bobcat
12-10-2021, 04:56 PM
Do you have something in the way of a service manual for this? I just pulled up a SAMS for this (Looked up the Royce 642 and it pointed me right to CB-280). According to SAMS it is the same as the Pace Model 8193. I pulled it up to look at it. I see the VR14 is the bias setting for the final..but I don't even find a VR13 in the parts list let alone the schematic.

The instructions for the final say....

Insert a 0-500mA DC Meter at TP11 (Junction of L5 and C77) I imagine you will have to lift a leg of L5....

then

set up Channel 19, USB, mic to minimum (don't want modulation) and key up

then

adjust VR14 for 80 mA of bias current.

If you need this manual let me know and I can try to find a way to attach and send it....
Update: nevermind...I think I got it attached to this post. Let me know!

Bob

3pinplug
12-10-2021, 05:44 PM
Hi Bob
Thankyou for your very quick response and info on the sams manual, i have a copy of the sams for the pace 8193 but it doesnt mention the other VR. I have managed to find the exact 643 schematic and that does shoe it and a volume of secret cb radio confirms both VRís are for the bias. Unfortunately i have been unable to find the factory alignment instructions only the sams you mention. Stuck on how to do it when you have 2 x VRís. Not much info out there on these lovely old rigs.
Regards
Mark

3pinplug
12-10-2021, 05:45 PM
Hi Bob
Thankyou for your very quick response and info on the sams manual, i have a copy of the sams for the pace 8193 but it doesnt mention the other VR. I have managed to find the exact 642 schematic and that does shoe it and a volume of secret cb radio confirms both VRís are for the bias. Unfortunately i have been unable to find the factory alignment instructions only the sams you mention. Stuck on how to do it when you have 2 x VRís. Not much info out there on these lovely old rigs.
Regards
Mark

Bobcat
12-10-2021, 06:38 PM
Sorry I could not be more help. I looked on CB Tricks and they have absolutely nothing on the 642. I even just went out to Defpom's site and... nothing. Again, I wish I could have done something more. Good luck getting her going!

Bob

3pinplug
12-11-2021, 01:31 AM
Hi Bob,
Thanks for trying bob, its very much appreciated.