[ARC5] Make that Old T-17 Work with BC-456

Thu Apr 2 21:49:04 EDT 2020

I used one of these in my T-17.  Works great.

73 Mark K3MSB

On Thu, Apr 2, 2020, 3:17 PM J Mcvey via ARC5 <arc5 at mailman.qth.net> wrote:

> An electret doesn't develop enough output to drive the modulator .. You
> only get 100 to 200 mv out
> You need current and voltage  amplification to drive the the lo-z input.
> I made these a few years ago. it will provide more that sufficient drive
> for 100% modulation.
>
>
> www.mcveyelectronics.com/military-radio/t-17-lollypop-microphone-cartridge-replacement-prototype
>
> McVey Electronics - Small drop-in PCB replacement for the carbon microph...
>
> Jim McVey
>
> Most of the T-17 mkes used inn WWII radio have poor or defective carbon
> cartridges, resulting in poor or no modu...
>
> <https://www.mcveyelectronics.com/military-radio/t-17-lollypop-microphone-cartridge-replacement-prototype>
>
>
>
> An electret doesn't develop enough output to drive the modulator .. You
> only get 100 to 200 mv out
> You need current amplification to drive the the lo-z input.
> I made these a few years ago. it will provide more that sufficient drive
> for 100% moodulation.
>
>
>
>
>
> On Thursday, April 2, 2020, 2:48:37 PM EDT, Scott Johnson <
> scottjohnson1 at cox.net> wrote:
>
>
> There are plenty of electret capsules out there that have a follower off
> the FET preamp that will drive a carbon input. I have had good luck with
> the three terminal capsules I have salvaged from computer mics, Sometimes a
> voltage dropping network is needed prevent overvoltage (DC) to the
> element.  Most are limited to 5-8 VDC.
>
>
>
>
>
> Scott V. Johnson W7SVJ
>
> 5111 E. Sharon Dr.
>
> Scottsdale, AZ 85254-3636
>
> H (602) 953-5779
>
> C (480) 550-2358
>
> scottjohnson1 at cox.net
>
> scott.johnson at ieee.org
>
>
>
> *From:* Doran Platt <jeepp2 at comcast.net>
> *Sent:* None
> *To:* scottjohnson1 at cox.net; arc5 at ix.netcom.com; arc5 at mailman.qth.net
> *Subject:* Re: [ARC5] Make that Old T-17 Work with BC-456
>
>
>
> I believe electret/carbon compatible mics all have an appropriate
> amplifier associated with it.
> K3HVG Jeep
>
>
> Sent from Xfinity Connect Application
>
>
> -----Original Message-----
>
> From: scottjohnson1 at cox.net
> To: arc5 at ix.netcom.com, arc5 at mailman.qth.net
> Sent: 2020-04-02 2:15:09 PM
> Subject: Re: [ARC5] Make that Old T-17 Work with BC-456
>
> Why not just install a 50 cent electret cartridge in the T-17, and call it
> a day?  (you’ll have the finest sounding T-17 around!)
>
>
>
> Scott V. Johnson W7SVJ
>
> 5111 E. Sharon Dr.
>
> Scottsdale, AZ 85254-3636
>
> H (602) 953-5779
>
> C (480) 550-2358
>
> scottjohnson1 at cox.net
>
> scott.johnson at ieee.org
>
>
>
> *From:* arc5-bounces at mailman.qth.net <arc5-bounces at mailman.qth.net> *On
> Behalf Of *David Stinson
> *Sent:* Thursday, April 2, 2020 11:00 AM
> *To:* ARC-5 <arc5 at mailman.qth.net>
> *Subject:* [ARC5] Make that Old T-17 Work with BC-456
>
>
>
> Got a BC-456 modulator you want to use, but only "dud" T-17 mikes?  Yes;
> in a perfect world, we'd wait and search until we found a "good" T-17.
> This world ain't perfect.  I don't know about you, but the sand in my hour
> glass is getting a little low, and given the current world situation,  I'd
> kinda like to enjoy my gear before "Ol' Grim" comes to collect me.
>
> So if you're T-17 will so even 10% mod, here's a non-destructive way to
> change two resistors and get your BC-456 modulator singing for you:
>
>
>
>
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>
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