PSK Microphone input

[Andrew Catanzaro]

Ralph,

Put the resistor between pins 1 and 6 in the *plug* for the
Heil Proset, rather than in the radio.  That way the Rascal interface works,
and no blocking capacitor is necessary.  Another advantage is that
you can use other microphones that don't require a bias voltage with
the K2.  The Heil dynamic elements still sound significantly better
than the electret elements in the MH-2 (discontinued) and Heil
Proset boom microphone, although the K2 output is somewhat less.
When I use the K2 with a Heil HC-5 element and a linear RF amplifier,
I get the best audio reports.  The Proset is still useful for Field
Day and other operations away from home.

Although there are published pre-amp circuits for using low-output
dynamic mikes with the K2, it isn't clear to me why it wasn't
designed with higher audio gain to start with.  That way higher quality microphones
could be used.  The K2 is capable of quite high quality transmit
audio, but it isn't as apparent with the electret microphones. Icom et
al have made the break with electrets starting with their Pro II and later
rigs.  We are still using the equivalent of the older style Icom mikes.

Andy W9NJY
Milwaukee
K2 2651
KX1 1139
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[G3VVT]

 
In a message dated 28/10/05 12:35:50 GMT Daylight Time, [hidden email]  
writes:

The K2  is capable of quite high quality transmit
audio, but it isn't as apparent  with the electret microphones. Icom et
al have made the break with  electrets starting with their Pro II and  later
rigs.


------------------------------------------------------------------------
 
The selection of a microphone type may take a little more care as it  depends
a lot on the tonal range of your voice to which type is suitable and  more
particularly so in the case of SSB. One type may be OK for one person yet  may
be useless for another.
 
I struggled for many years to find a suitable microphone for SSB where  there
was no problem with 2m FM. Ended up with a varied selection of dynamic  
microphones from Shure, Kenwood, Yaesu and many other manufacturers. The type  that
finally worked was the old Adonis AM-303G electret microphone. However,  when
I tried to use the same type of electret microphone on 2m FM was firmly  told
what to do with it.
 
Have yet to try the Heil dynamic microphones to see what the effect is with  
them. Have an old Heil desk microphone (HM-5?) which came from an S/K sale
that  had been modified to high impedance use. Will change it back to original  
configuration and see how that works out. The insert in this is the HC-3  which
have been unable to find any info about. Did approach Bob Heil for  details
about the microphone and though he gave favourable comments  for the microphone
itself, was not forthcoming with any information or data  about the HC-3
insert.
 
Does anybody have any information about this Heil HC-3  insert?
 
Bob, G3VVT
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