[TenTec] D-104

[Frank Krozel]

To all AND especially Jerry, K0CQ:
I guess I stated my opinion too early.  Jerry is right on.  Oh... where is
Bob H on this discussion??
Frank Krozel KG9H
-----Original Message-----
From: Dr. Gerald N. Johnson, P.E. <geraldj@ames.net>
To: Beamer, Jay <JBeamer@PanAmSat.com>
Cc: 'Carl Hyde' <cshyde@yahoo.com>; 'tentec@contesting.com'
<tentec@contesting.com>
Date: Friday, June 11, 1999 11:17 AM
Subject: Re: [TenTec] D-104


>
>The D-104 has always been designed for AM with a strong rising frequency
>response. That was intended to overcome receiver selectivity by
>supplying audio preemphasis to the high frequency components, especially
>in the days of a rounded receiver selectivity curve. There weren't any
>D-104 with a flat response, the rising response was intentional.
>
>And like I've said before that rising response means most of the output
>power of the microphone is outside the transmit filter in a SSB rig so
>any audio processing before the balanced modulator and filter is screwed
>up and in some radios those high frequency components drive the audio
>and modulator into distortion leading to distortion products that pass
>through the filter.
>
>The relative phase response of the microphone, audio stages, and the
>transmit filter are important to punch as limited by the transmitter PA
>stages and ALC. Some microphones and filters (and voices) lead to a
>signal that has a poor peak to average ratio and some are much better. I
>find the EV 664 works well with my Yeasu FT-726 though I have a battle
>ship rated Turner hand mike (weighs a ton) does better. The microphones
>supplied by Yaesu have a lousy peak to average ratio. The Shure R5 does
>well on my S-line and Corsair II.
>
>I've not found that the Shure R5 element (used in the 520 "Dispatcher"
>microphone eons ago) is still available. Distributor catalogs don't show
>it but also don't show it as obsolete. I have my local distributor
>checking...
>
>73, Jerry, K0CQ
>
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