View Single Post
Old 20th Sep 2017, 9:29 am   #1
Damo666
Hexode
 
Join Date: Jan 2010
Location: Blackburn, Lancashire, UK.
Posts: 399
Default Midland Portapack 77-805 CB power meter problem

I've just picked up a Midland 77-805 and it's working superbly on receive and transmit, however, there's a niggle with the power meter reading when working on its telescopic antenna.

With all cells fully charged and working into a dummy load, the rig is outputting 4W into a power meter and lighting the corresponding 4 red LED power lights on the rig TX power meter.

I've also connected the rig to a variable power supply and varied the voltage from 10.5V to 13.2V, and the rig shows 1 LED for 1W, 2 LED's for 2W, 3 for 3W, 4 for 4W etc'.. All is as should be into a dummy load.

With the Telescopic antenna installed and a full battery pack (10 x NiMh AA) connected, when I key, the power meter on the rig is only just lighting 1 led - but signal reports are good from several miles away.

I had one of these many years ago and didn't have this problem, and a YouTube search on this rig shows other people's TX meter light all 4 LED's when used in the same circumstances as me.

I was going to alter the TX meter variable resistor, but as it's reading perfectly fine into a dummy load it's seemingly set up factory perfect.

By the way, I checked for continuity from the telescopic antenna stud to the tip and all is good as I suspected the centre load coil might've been open circuit.

Can anyone tell me what the problem could be?

There is an original schematic here - http://www.cbtricks.com/radios/midland/77_805/index.htm

Last edited by Damo666; 20th Sep 2017 at 9:36 am. Reason: Schematic added
Damo666 is offline