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THE AM BULLETIN BOARD => Technical Forum => Topic started by: W1KSZ on May 22, 2019, 11:37:18 AM

Title: Turner SR90D Mike Element Replacement
Post by: W1KSZ on May 22, 2019, 11:37:18 AM
I have a nice looking SR90D Dynamic Mike that I want to keep and use.
It's just too nice looking to pitch !!

Any ideas on what I can replace the Mike Element with ?

Tnx, Dick, W1KSZ

Title: Re: Turner SR90D Mike Element Replacement
Post by: KK4YY on May 22, 2019, 01:16:56 PM

It rather depends on what you intend to use it for. Hand held mics need a durable element because they are subject to hard knocks, like being dropped. If used in a mobile situation, they must be able to withstand wide temperature and humidity variations. These requirements can be met with a dynamic element, like the one your mic had originally. Mobile mics can also benefit from a noise-cancelling design, or at least should be close-talked.

If, in your shack, you simply prefer to use a hand held mic, your choice of elements are a bit broader but they should still be able to withstand an accidental drop or two.

A dynamic or electret condenser element would be a good choice, the latter being small, inexpensive, and having a good frequency response. The electret condenser requires a small DC voltage that would need to be provided either by the radio or a battery. If that interests you, a good place to start would be here:

I built one following those plans and it worked just fine. In fact, I still use the pre-emphasis network that Rob W1AEX describes on that page, but I mounted it inside of a Marshall MXL-770 condenser mic. If you've heard me on-air recently, that's what you were listening to (with a bit of processing after it).


Title: Re: Turner SR90D Mike Element Replacement
Post by: PA0NVD on May 22, 2019, 01:57:46 PM
Hi Dick
I completely agree with Don, those electret elements sound great. I also use one for my Philips transmitter with a small adjustment to get a little less low end, just like Don. And you cen get them both inj noise canceling and in no-noise canceling versions. The noise canceling version has little holes drilled in the backside PCB so the sound can enter also from the back. I used them in my UL airplane with success.

Title: Re: Turner SR90D Mike Element Replacement
Post by: W1KSZ on May 23, 2019, 01:26:20 PM
Thanks for the replies. If I decide to cobble up some replacement,
my choice would be the Heil D-104 cartridge replacement.

I have done two D-104's this way and they sound great on AM.

I was hoping to find a drop-in replacement for the Turner, so I
will keep on looking for now.

Tnx es 73, Dick, W1KSZ
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