[Elecraft] MH-2 and Boomset Problem

[Don Wilhelm]

Mark,

The fact that the mic plug CAN plug directly into the K2 does not mean that
it is wired correctly for the K2 - this is a problem with mics and the
various mic pinout configuration that different manufacturers use.  The
Elecraft configuration is very much like the Kenwood, but it still differs
by one pin (pin 5 vs. pin 6 for +5 volts).

Be aware that the Heil HC4 and HC5 elements have much lower output levels
than the electret type mics (those made for Icom and Elecraft are two
examples of Electret types).

My suggestion to solve your problem is to build an external pre-amp to bring
the HC-5 element up to a decent output (about 6 dB gain is what I would
suggest) and in the box where the pre-amp resides, you could make the input
connector wiring to match your Yaesu wired microphone, and wire the output
plug to match the Elecraft pin configuration.  That way, you could attach
the MH2 directly to the K2, but attach the BM-10 mic with the Yaesu adapter
to the preamp and the preamp box connects directly to the K2.  I can send
you a schematic of the preamp I use (which allows the 5.6k resistor to
remain wired in the K2) should you need one - send me a direct email, the
reflector rejects attachments.

Yes, it is more complicated than simply plugging in the mic, but your
variety of transceivers that you intend to use the mic with creates
complexity itself - the solution I suggested, once constructed removes the
complexity.

73,
Don W3FPR

> -----Original Message-----

> Hi Don,
>
> This is much more complex than I originally thought!
>
> The BM-10 was purchased with adapters for an Omni 6 (4-pin) and a Yaesu
> 817 (RG-xx). The pads are black and it has the HC-5 element.  The cord
> coming from the boomset has a connector that takes either above adapter,
> or, it can go directly into the K2 mic connector.  The headset only had
> BM-10 shown as its model number.
>
> All this discussion may be why I only do about 20 SSB Q's/yr on HF! Now
> in the VHF rover I do 1000+/yr, but we the Yaesu hand mics that came
> with the rigs.
>
> Thanks,
> Mark K2QO
>
> Don Wilhelm wrote:
>
> >Mark,
> >
> >Still not enough info - BM-10 is a Heil number, not an Elecraft
> number, and
> >there are 3 models of the BM-10 - one with the HC-4 element, one with the
> >HC-5 element and one with an electret element for Icom.  Are the
> pads blue,
> >red, or black?
> >
> >The above info is only for starters - these mics are sold by Heil for
> >specific rigs and vary in the wiring at the plug, so you must also know
> >which transceiver it was originally intended for.
> >
> >If I had to guess, I would say that your BM-10 is wired for the
> Yaesu which
> >uses pin 6 for PTT, and when you connect it to the K2 and press the
> >footswitch, you are shorting the K2 +5 volts pin (6) to ground.
> Heil refers
> >to the Yaesu BM-10 as BM-10-Y, but I don't know whether that is simply
> >ordering info or if that number is imprinted on the mic.
> >
> >73,
> >Don W3FPR
>