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Call Sign : 26-CT-4502 Posts : 11 Times Thanked : 0 Join date : 2022-04-26 QTH or Location : Bournemouth Equipment Used : Baofeng UV-5R, PNI Escort HP 6500 Age : 50
Subject: Midland 77-095 power adjustment query. Tue May 17, 2022 7:28 pm
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
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Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5803 Times Thanked : 352 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Midland 77-095 power adjustment query. Tue May 17, 2022 8:54 pm
Hi Craig,
I know you asked about some info for this rig before :-
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
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craigd230 New Member
Call Sign : 26-CT-4502 Posts : 11 Times Thanked : 0 Join date : 2022-04-26 QTH or Location : Bournemouth Equipment Used : Baofeng UV-5R, PNI Escort HP 6500 Age : 50
Subject: Re: Midland 77-095 power adjustment query. Tue May 17, 2022 9:11 pm
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.
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5803 Times Thanked : 352 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Midland 77-095 power adjustment query. Tue May 17, 2022 9:29 pm
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.
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Alan Pilot Major contributor
Call Sign : 163-CT-220...MW7TTA Posts : 2516 Times Thanked : 69 Join date : 2019-11-19 QTH or Location : Anglesey North Wales Equipment Used : Yaesu FT-991A,,Yaesu FTDX-10,,Icom ic-7300,,Anytone AT-D878UV PLUS",,LINCOLN II+. Age : 150
Subject: Re: Midland 77-095 power adjustment query. Wed May 18, 2022 8:44 am
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.
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craigd230 New Member
Call Sign : 26-CT-4502 Posts : 11 Times Thanked : 0 Join date : 2022-04-26 QTH or Location : Bournemouth Equipment Used : Baofeng UV-5R, PNI Escort HP 6500 Age : 50
Subject: Re: Midland 77-095 power adjustment query. Wed May 18, 2022 8:32 pm
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
Victor likes this post
Victor CT Directors
Call Sign : 26-CT-3228 / M7VIC Posts : 5803 Times Thanked : 352 Join date : 2019-11-10 QTH or Location : Bedford Equipment Used : Various
Subject: Re: Midland 77-095 power adjustment query. Wed May 18, 2022 9:03 pm
That's great news and happy to hear. Well done.
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