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Best Microphone for Drake T-4XC

Dec 17th 2015, 19:20

Jshumberg

Joined: Aug 21st 2015, 00:19
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Hello all. I am new to amateur radio and I have purchased a set (Drake T-4XC and TR4C) to make ready while I pursue my license. My question is what is the best microphone for this set? I prefer a desk type microphone. Thanks. Jim in Houston
Dec 17th 2015, 20:46

W1VT

Super Moderator

Joined: Apr 4th 1998, 00:00
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The D104 high impedance mic was a good match for your Drake, but sadly, many of these mics have crystal elements that no longer work.

http://www.k3dav.com/astaticd104microphone.htm
Some history of the D104.

You may want to measure or test the size of the mic plug--while they came with 0.206 diameter plugs, your set may have been modified for a 1/4" plug.

You want to avoid low impedance dynamic microphones. A Kenwood MC-50 has a built in transformer and switch for both 600 and 50k ohms mic impedances.

Zack Lau W1VT
ARRL Senior Lab Engineer
Dec 17th 2015, 23:31

Jshumberg

Joined: Aug 21st 2015, 00:19
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Is the Shure 450 a good match? When you say high impedance, how much impedance are you talking about?
Thank you for the quick reply.
Dec 18th 2015, 15:20

W1VT

Super Moderator

Joined: Apr 4th 1998, 00:00
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High impedance is typically over 50k ohms.

The D104 had an impedance of 50k to 100k ohms
http://www.k3dav.com/astaticd104microphone.htm

The MC-50 has a high impedance setting of 50k ohms.

The 450 is a poor match--a dynamic mic typically has an impedance of just 500 or 600 ohms. Actually, the problem isn't so much the impedance, but the low output voltage seen by the input of the transmitter.

If I had a rig with the 0.206 plug, I might take a gamble on buying a D104 that the seller claims is in working condition. If it has been modified for a 1/4 inch plug, I'd probably go for something like the MC-50 that has a transformer built in to handle high and low impedance--then I could also use it with a newer rig that requires a low impedance mic. High impedance mics are hard to find because the rigs that need them haven't been made for decades. And, as I pointed out earlier, crystal mics don't age well, so while they were common 30 years ago, many of them no longer work. There are also high impedance hand mics on Ebay, but you wanted a desk mic.

Zack Lau W1VT
ARRL Senior Lab Engineer
Dec 19th 2015, 22:57

Jshumberg

Joined: Aug 21st 2015, 00:19
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Total Posts: 0
Thanks Zack. Good info.

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