"PDRUNEN" wrote in message
...
Hi Group,

Got a 706 which has a 500 or 600 ohm mic input impedance. I have a D104
which
best I can tell has a high output impedance.

If I use a 60Hz step down transformer, say, 120V in gives 10v out, the
turn
ratio is 120/10 or 12:1. Given that I attach the mic output to the
primary and
the rig on the secondary, this should step down the impedance by a factor
of
12^2 or 144 so that a D104 with 50K on the output is now seen as about 400
ohm.

Here are a few questions,

1: Will a 60Hz transformer work well keeping the base sound and pass upto
3KHz?

2: Is the calculation of the impedance correct?

3: Would the audio as seen on the secondary be reduced by a factor of 12
such
that the audio would be weak?

4: Other?

Tnx de KJ4UO

Paul -

First, The D104 microphone was manufactured by Astatic, a division of
Omnitronics.
Omnitronics LLC
341 Harbor Street
Conneaut, OH 44030
http://www.astatic.com/

There are several models of the D104 microphone (e.g., stand combinations,
transistorized preamp, etc.) - detailed on their web site.
All D104 microphone that I am aware of ... use a high impendence
ceramic/crystal microphone element.
Wiring diagrams for the 8-pin Icom (not the RJ-45 jack version) is on their
web site.

Some operator have switched the D104 to Heil dynamic elements (HM-4 or
HM-5).
Astatic no longer has the crystal elements, but Mouser has a good Far East
substitute.
http://www.mouser.com/

This make a big difference in your approach -- since some of these bases
have a low-Z / high-z switch in the amplifier OR
actually have an audio transformer in the base for this purpose.
The Heil XT-1 is a suitable transformer, Mouser has several candidates in
their catalog.
Radio Shack use to some suitable audio transformers for $ 2 or so.

Xicon has some candidates (e.g. Mouser # 42TM017; 42TM019; 42TM024) .. with
differing input impedances (25K and 10K) and power capability (not a major
issue for your application)

Greg, w9gb