Midland 77-095 power adjustment query.

Aquired a Midland 77-095. With a 10w dummy load connected on tx output power is only registering on my power meter as 2.5. Need to crank the radio up to 4w.


What potentiometers on the board do I need to tweak ?


Look forward to help on this.


- Craig

Hi Craig,

I know you asked about some info for this rig before :-

https://charlietangodxgroup.forumotion.com/t4396-wanted-midland-77-095-user-manual-service-book

The only thing I could find off hand was the circuit diagram but not sure if this alone is helpful for you :-

https://elektrotanya.com/midland_77-095_sch.pdf/download.html

If you're up to the task and have an appropriate trimmer tool the following video may help you :-

https://www.youtube.com/watch?v=-xGKHtonFQ0

That's presuming that everything is OK with the rig in the first place but worth a punt nonetheless.
(Screams of 'golden screwdriver' ringing out right there! )


As for appropriate trimmer tool you can't go much further wrong than shaving the pointy bit on a bic-biro pen cap to a small screwdriver shaped end and using that with the plastic being soft enough not to go cracking those ferrite cores(!)

So more of a plasticky-golden-screwdriver I suppose.

(A trick I've often used when stuck for an appropriate soft trimmer tool. )

Just don't go using one of those 'jewellers' small metal screwdrivers...you'll only regret it.


I hope that helps you and remember anything you do to b*gger up your rig is your own fault not mine.
(Legal disclaimer I suppose. )

I wish you well and best of luck.


All the best,
Victor

Cheers Victor

Strange the way the transmitter needs multiple potentiometers tweaked to get the radio to 4w. You would of thought they would of just opted for one pot for transmitter power adjustment.

Well, it's actually a bit more complicated than that. VR5 on the schematic, the actual potentiometer and not the metal canned coils, is the actual power adjustment made by adjusting the bias to the output or P.A. (power amplifier) transistor.

Just don't go mad twiddlling it all trying to squeeze more power out and be happy with a measured 4 watts.

If unsure don't touch.
As Victor said there is a lot more to it than many think there is.
If you must then mark them first with a pointy marker i know it won't get you back spot on but it might get you close to where it was.

Success. Radio is now outputting 4 watts with dummy load connected according to my power meter.

Did a tx test to my other radio. All working good

That's great news and happy to hear. Well done.