Hi Tom,
Haven't tried any of Bob's mikes on my Jupiter yet,so I can't comment on
them.However your comments on mike impedance are right on the money.I have a
modified D-104 that worked real good with my Scout-when I got the Jupiter,it
would not fly;seems the input Z of the Scout is abt 100K ohms(which is a
10/1 Z mismatch according to the data I pulled out of 1936 ARRL Handbook-I
do boatanchor restorations and these old Handbooks really come in handy.When
I got the Jupe,I found out that yhe input Z was <50K (abt a 20/1 mismatch)
and it would not drive the Jupe w/o putting a FET preamp in the base and
using a Heil XT-1 matching xfmr wired in REVERSE to get a good match to the
Jupe.FYI,the data in the 1936 Hdbk gives the Z of an unamplified D-104 as >
1meg;great for tube sets but not so good for solid state.Just remember,some
fella named Thevinin postulated the for max transfer of energy,the Zof the
source must equal the Z of the load.
Best 73 de Bill W4NJF
----- Original Message -----
From: "Tom North" <tomnorth@airmail.net>
To: <tentec@contesting.com>
Sent: Wednesday, October 29, 2003 12:35 PM
Subject: [TenTec] Re: what is so special about heil microphone elements?
> A good basic explanation of what Bob Heil is up to with the HC-4/5 and
> derivitives is on their website at
> www.heilsound.com
> Bottom line is that he has tailored these elements to 1) expected
bandwidth
> in SSB and 2) manipulated the response curves to take advantage of the
voice
> characteristics to enhance 'punch' or a natural sound, depending on the
> element.
>
> Then we have impedance. The older Shure's, Aststics et al are high
> impedance, usually on the order of 50K or better. The exception will
appear
> to come with an amped mic, such as the later Astatics. Heil's stuff is low
> impedance, 1K I believe, and will match better to the newer rigs - Omni V
> etc. The high impedance mice are easier to get sounding 'right' with the
> older rigs, the Tritons, Omni A-D etc., from what I've seen here.
>
> IMHO, to get the best sound with any mic/rig is to use a monitor scope in
> the output. This is particularly the case with the older rigs that rely on
> the ALC lamp for indication. It will also be a benefit to those with a
> meter; I have found the actual results to be deceiving after learning how
to
> use the scope and after a number of QSO's. I have an old Yaesu YO-100 that
> tells me what my sigs look like, AGC action, and when it begins to clip or
> distort. There are various scopes out there, including Heaths and
Kenwoods,
> that will accomplish the same goal. It needn't be calibrated or fancy, but
> that doesn't hurt either if one wishes to get into accurate two-tone and
> trap measurements, with the proper knowledge and standards to drive it.
> Coupling a good bench scope is easy if this makes sense.
>
> 73,
> Tom N5OZQ
>
>
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