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Turner M+3 mic and M+2U
Posted: Thu Feb 22, 2018 11:59 pm
by 479tx
GF -
How'd you modify your M+3 for wider audio?
Thanks!
Re: turner m+3 mic
Posted: Fri Feb 23, 2018 6:00 pm
by Goldfinger
As there is no schematic of the amplifier, I did it by studying the PC board and changing a few caps. They actually have a wider response stock than any other Turner (base or mobile) or stock amplified D-104. It responds down to 80hz well from the factory. The only stock CB powermic that goes lower is the 575.
I did the work years ago so I'd have to take it apart to see what I changed.
Re: turner m+3 mic
Posted: Fri Feb 23, 2018 9:37 pm
by 479tx
http://www.cbtricks.com/mic_manuals/tur ... m-plus.pdf
Docs say the mic goes down to 300hz stock. I found a nice one so I'm going to check it out on a cap modded 29.
Re: turner m+3 mic
Posted: Sat Feb 24, 2018 5:54 pm
by Goldfinger
It might say 300 but I swept mine and it goes lower.
That manual has the wiring diagram but the amp is depicted as a triangle only and has no detail.
Re: turner m+3 mic
Posted: Wed Apr 24, 2019 4:55 pm
by 479tx
Re: turner m+3 mic
Posted: Wed Apr 24, 2019 4:55 pm
by 479tx
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Re: turner m+3 mic
Posted: Wed Apr 24, 2019 4:58 pm
by 479tx
The electrolytics are 2uf, 2uf, 5uf
Re: turner m+3 mic
Posted: Thu Apr 25, 2019 9:28 am
by 31
?
Re: turner m+3 mic
Posted: Sat Apr 27, 2019 4:27 pm
by Goldfinger
I'll pop mine apart in the morning and post up info then.
Re: turner m+3 mic
Posted: Sun Apr 28, 2019 10:36 am
by 479tx
Thanks GF!
Re: turner m+3 mic
Posted: Fri May 03, 2019 8:58 pm
by 479tx
Breaker, Breaker Goldfinger... Was your mic stuck together?
I found two cherry JM + 3 mics would love to fatten the audio up.
Re: turner m+3 mic
Posted: Sat May 04, 2019 9:13 pm
by Goldfinger
I recently had minor surgery and several doctor appointments so though I have it apart and looked a little, I didn't finish mapping out the circuit yet. It looks like the first to second stage might be DC coupled.
Anyway, I should have some time in the next couple days..
Re: turner m+3 mic
Posted: Mon May 06, 2019 8:51 am
by 479tx
Not a problem sir! Take care of your health. Hoping you have a speedy recovery.
Re: turner m+3 mic
Posted: Sat Dec 28, 2019 6:32 pm
by Goldfinger
Make this .01uF disc lower in value for more highs. Don't go too small or it may invite RF squeal.
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For a little bass boost change this 1Mohm to a 1.5Mohm or add a 470k in series.
- +3-2a.jpg (115.09 KiB) Viewed 4589 times
The entire circuit is DC coupled like a Hi-Fi audio amp including the compression circuit. The mic element is even DC coupled to the BASE of the first audio amp. The only cap to change is the 5uF electrolytic below the volume control. Change to a 10uF.
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The other electrolytics are in the feedback loops for the compression so don't need to be changed.
The compression is fairly complex as it samples the output of both stages of the audio amp. This sample is coupled through both 2uF electrolytics to the FET in the middle. The FET applies this signal back to the second audio amp stage inverted varying the gain of the circuit in step with the signal amplitude.
Re: turner m+3 mic
Posted: Sun Dec 29, 2019 4:33 pm
by 479tx
Thanks so much, GF! I'm going to mod one of my M+3's tonight!
Re: turner m+3 mic
Posted: Wed Jan 01, 2020 12:05 pm
by 479tx
This mod seems to work excellent. I can definitely tell a difference in low-end frequency response on my modified M+3 vs. stock when running them on a 29 modified for wide transmit. Excellent!
Re: turner m+3 mic
Posted: Thu Jan 02, 2020 10:11 am
by Goldfinger
Great!
Re: turner m+3 mic
Posted: Tue Feb 18, 2020 4:48 pm
by Tinybilt
Nice!
Re: turner m+3 mic
Posted: Tue Aug 17, 2021 4:15 pm
by DarkStar
Goldfinger,
Is there a mod to broadband the Turner J/M+2 in order to get rid of some of the bass and bring out some of the highs? I tried adding a .01mf cap in line with the white (audio) wire but was not happy with the results. It just made the mic sound flat and it seemed to lose all of the richness of the sound. Are there anything else that you could recommend be done to this mic? Thanks and 73s
Tom
Re: turner m+3 mic
Posted: Wed Aug 18, 2021 8:39 am
by Goldfinger
For less bass, change C5 to a 1uF or a 2.2uF, 16 volt electrolytic. Observe polarity
For more highs, change C6 to a .0047uF ceramic disc or mylar/polyester.
One more thing you can try if the first two mods don't get what you want is to shift the feedback center frequency by changing C1 to a .0047uF ceramic disc or mylar/polyester.
- Turner m+2 Jm+2 schematic.jpg (101.26 KiB) Viewed 2293 times
Re: turner m+3 mic
Posted: Mon Aug 23, 2021 10:51 pm
by DarkStar
I'm gonna order up some parts from Mouser and give this a shot. I always loved this mic for ssb but found it to be a bit too bassy for the am side. It sounds like this will brighten it up a bit. Thanks a ton Goldfinger!! 73s
Re: Turner M+3 mic and M+2U
Posted: Mon Oct 16, 2023 10:10 pm
by Goldfinger