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Post by sfi355 aka Billy Bob on Oct 12, 2019 21:09:29 GMT -5
I picked up a Midland 13-877. it didn’t come with a power connector. I can not find and information on this radio radio of which pins are for the AC hook up. And how to wire up a Mic for it. Any help or point me in the right direction. Thanks
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Post by cbrown on Oct 16, 2019 13:13:57 GMT -5
AC I can't help with, and I had to best guess microphone wiring (its based on both the Pearce Simpson Bearcat 23 and Regency Formula 23 which share almost the same chassis)
Pin 1 should be audio feed Pin 2 should be shield
Here is where is gets tough:
Pin 3 on a Bearcat is TX (activates the relay)
Pin 3 on a Formula is also ground, but for the TX Pin 4 is TX
This should get you in the ballpark.
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Post by sfi355 aka Billy Bob on Oct 16, 2019 20:08:59 GMT -5
AC I can't help with, and I had to best guess microphone wiring (its based on both the Pearce Simpson Bearcat 23 and Regency Formula 23 which share almost the same chassis) Pin 1 should be audio feed Pin 2 should be shield Here is where is gets tough: Pin 3 on a Bearcat is TX (activates the relay) Pin 3 on a Formula is also ground, but for the TX Pin 4 is TX This should get you in the ballpark. Thank for the information. But the Midland 13-877 has the 1/8 inch Plug for the mic connector. Not a 4 pin barrel
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Sandbagger
Administrator/The Boss
Posts: 6,245
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Post by Sandbagger on Oct 17, 2019 6:44:32 GMT -5
AC I can't help with, and I had to best guess microphone wiring (its based on both the Pearce Simpson Bearcat 23 and Regency Formula 23 which share almost the same chassis) Pin 1 should be audio feed Pin 2 should be shield Here is where is gets tough: Pin 3 on a Bearcat is TX (activates the relay) Pin 3 on a Formula is also ground, but for the TX Pin 4 is TX This should get you in the ballpark. Thank for the information. But the Midland 13-877 has the 1/8 inch Plug for the mic connector. Not a 4 pin barrel That should be simpler. If it's like the 13-885, the audio is on the tip, the TX switch is on the ring, and the ground is on the shell of the plug.
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Post by 321 treeclimber on Oct 17, 2019 9:38:35 GMT -5
I have an old mic I'd like to use with an old audio plug on it,which i want to keep as is. Can i set up a foot switch and feed it in to a 4 pin plug ?
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Post by sfi355 aka Billy Bob on Oct 20, 2019 21:41:09 GMT -5
I have an old mic I'd like to use with an old audio plug on it,which i want to keep as is. Can i set up a foot switch and feed it in to a 4 pin plug ? I was able to hook up a 12 volts to it, but as I found out is that all the Capacitors needs replacement. So I will be donating it due to that I don’t want to go through the time or the expenses to restore it. Thanks for all your help.
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Post by cbrown on Oct 23, 2019 14:58:21 GMT -5
I have an old mic I'd like to use with an old audio plug on it,which i want to keep as is. Can i set up a foot switch and feed it in to a 4 pin plug ? Sure. Not difficult at all.
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Post by 321 treeclimber on Oct 23, 2019 16:28:32 GMT -5
Where do i start?
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Post by cbrown on Oct 30, 2019 12:55:27 GMT -5
Best bet would be with a foot switch. Seriously though, find yourself a momentary foot switch. Then look for some 2 conductor shielded audio cable. You'll use both conductors for the audio feed, and use the shielding to ground the cable to help prevent RF from getting inside. Depending on the run length of the audio cable, you might have to add some snap on ferrite suppressors. Next you'll need a female microphone connector to accept the plug on the microphone you intend to use. Its probably the standard 1/4" mono phone plug, so you'll need the female. Then you'll need the 4 pin connector. Once you have all these items together, let me know what radio you are going to wire and what microphone you plan on using and I'll give you the wiring (and let you know if the microphone you plan to use will actually work without modifications).
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Post by 321 treeclimber on Oct 30, 2019 17:48:36 GMT -5
Great! I will get parts together right away. I'll give you the mic and radio info in a couple hours. Thanks man
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Post by 321 treeclimber on Oct 30, 2019 19:28:48 GMT -5
Best bet would be with a foot switch. Seriously though, find yourself a momentary foot switch. Then look for some 2 conductor shielded audio cable. You'll use both conductors for the audio feed, and use the shielding to ground the cable to help prevent RF from getting inside. Depending on the run length of the audio cable, you might have to add some snap on ferrite suppressors. Next you'll need a female microphone connector to accept the plug on the microphone you intend to use. Its probably the standard 1/4" mono phone plug, so you'll need the female. Then you'll need the 4 pin connector. Once you have all these items together, let me know what radio you are going to wire and what microphone you plan on using and I'll give you the wiring (and let you know if the microphone you plan to use will actually work without modifications). ok cb,going to use a astatic jt-30 on a comstat 25a
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Post by 321 treeclimber on Oct 31, 2019 7:18:02 GMT -5
Hey c brown, can you also reccomend a foot switch? Something with an old school look. Thanks, 321
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Post by 321 treeclimber on Nov 1, 2019 7:35:23 GMT -5
Picked up a normally open,momentary foot switch. Found a female plug end and some audio cable.
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Post by bobcat4109 on Nov 1, 2019 9:28:56 GMT -5
13-877 Power Connector
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Post by cbrown on Nov 6, 2019 14:05:37 GMT -5
Hey c brown, can you also reccomend a foot switch? Something with an old school look. Thanks, 321 I like the Heil foot switches myself, I use a FS-2 since I have a small tube driver powering my bigger tube amp and this switch allows me to key both with just a bit of delay between to two.
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Post by cbrown on Nov 6, 2019 14:31:43 GMT -5
Picked up a normally open,momentary foot switch. Found a female plug end and some audio cable. 4 pin connector for Comstat 25A: Pin 1 - Audio line Pin 2 - Transmit Pin 3 - Audio Line (shield side) Pin 4 - Ground The 4 pin connector inside the Comstat has bot pins 3 & 4 grounded. Remove the current connector (if any) on the end of the momentary foot switch. Connect one of the wires to pin 2 on your 4 pin connector and the other to pin 4. This is your TX/RX connection. Until you press on the foot switch the radio will be in receive mode. Then take your 1/4" female TS (tip/sleeve) connector and solder one of the wires in the audio cable to the tip connection. Solder the other end of that audio wire to the male TS connector, also at the tip. (picture below in case you don't know tip/sleeve) Solder the other wire (and any shield wires) to the sleeve connection on both the male plug and the female jack. Be careful not to get any cold solder joints in the audio connections. All should be good to go. Step on pedal to transmit, lift foot to receive. Let me know if you have any problems following this.
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Post by 321 treeclimber on Nov 6, 2019 18:22:41 GMT -5
This looks pretty straightforward. I will be able to do this tomorrow night. Thanks cb. Will let you know how I make out as soon as its together. 321
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Post by 321 treeclimber on Nov 6, 2019 23:22:02 GMT -5
Ok, I got the itch and did the work tonight...well,not quite a success but not a total failure. I seem to be missing something. built it as you said and the radio keys but no audio out. Tried another mic that has a ptt and 1/4 phone jack.plugged that into the female phone jack, depressed foot switch and it worked great but not with the jt-30 mic. What am I missing?
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Post by cbrown on Nov 8, 2019 13:37:02 GMT -5
The JT-30 series microphone came in two types (actually all Astatic heads did for the most part), the crystal version and the ceramic version. Early Astatic crystal microphones used Rochelle Salt crystals which could be damaged by physical or thermal shock, extreme temperatures, application of a voltage in excess of the mics specifications across the crystal element or any number of other reasons.
Look for shops that deal in harmonicas, the JT-30 and the T-3 are favorites of harmonica players and you should be able to find a replacement element.
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Post by 321 treeclimber on Nov 8, 2019 21:38:17 GMT -5
Thanks CB. You have been a great help.321
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Post by cbrown on Nov 13, 2019 13:34:21 GMT -5
Thanks CB. You have been a great help.321 Glad to be able to help out! I did find a few places selling replacement elements, but oh boy do they want $$$ for them. Genuine Astatic Crystal Element!!! - $165.00 - www.jt30.com/eacstore2.htmlVintage MC-151 Crystal Element - $199.95 - www.dirtydansmics.com/parts.htm
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Post by 321 treeclimber on Nov 13, 2019 14:21:38 GMT -5
Wow! That's big bucks! Well thanks again, I'll keep lookin.
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Post by cbrown on Nov 20, 2019 13:41:59 GMT -5
If you're looking for Astatic heads that will work on Hi-Z tube equipment, the DN-HZ was always a good choice. Same frequency response as the JT-30/T-3 heads.
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Post by 321 treeclimber on Nov 20, 2019 15:39:20 GMT -5
10-4 cb. Ok, another good chunk of info. Will actually order something this weekend.
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