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THE AM BULLETIN BOARD => Technical Forum => Topic started by: WA2ROC on December 15, 2010, 12:42:09 PM



Title: Shure 444 vs. Johnson CM17K
Post by: WA2ROC on December 15, 2010, 12:42:09 PM
Are these two microphoniums related in any way?  I just picked up the CM17K and it has some sort of "amplifier" inside that doesn't seem to do anything, probably because it doesn't use a power source of any kind.

There is audio output from the mike cors into my scope, but the output remains constant no matter where the "volume control" is set. 

And "No", the output of the mike element isn't connected directly to the mike cord.



Title: Re: Shure 444 vs. Johnson CM17K
Post by: Pete, WA2CWA on December 15, 2010, 12:59:46 PM
See: http://cgi.ebay.com/Vintage-SHURE-Desk-mic-preamp-ham-radio-/320629941115


Title: Re: Shure 444 vs. Johnson CM17K
Post by: WA2ROC on December 15, 2010, 01:34:33 PM
Thanks Pete.  You never know what information you'll find on Flea-Bay.

I just bypassed the preamp since this mike will be used on either my Apache or the KT-390. 

This mike also has a replacement element, not marked in any way, and the base is labeled "Johnson".

Time will tell....


Title: Re: Shure 444 vs. Johnson CM17K
Post by: WA2ROC on December 18, 2010, 10:26:54 AM
Yep, I found that out quickly.  It's on the way back to the seller now.

Merry Christmas!
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands