[Elecraft] Heil Headset HC-5

[Don Wilhelm]

Jack,

You are quite correct, I know you and some others have been successful 
with increasing the KSB2 R14 resistor value, but that will change the 
loading on the MH2/MD2 mics (which can change the audio output 
characteristics).  Since Dave wants to use the MH2/MD2 directly on the 
K2, in this case I believe the external preamp/adapter is the best 
approach.  Using the mic 5 volt line has its limitations, but with a 
short cable between the preamp box and the K2 I have not had problems 
powering the preamp - just don't load it down or use a long cable (6 
inches to 1 foot is enough).

Of course how to implement it is an individual choice, I can only speak 
for the implementation that I see is easiest for all the factors in 
consideration, but the final choice is up to the individual builder. 
There are many workable choices available.

73,
Don W3FPR

Jack Brindle wrote:
> Sigh. Don and I have agreed to disagree on this point. I have used my 
> K2/100 quite successfully for several years with a Heil Pro headset. 
> Mine has the HC-4 element.
> 
> I would try it _without_ the preamp  just to see how it works for you 
> before deciding you need the extra box. You may end up needing one, or 
> things might work just fine.
> 
> I would also wire the resistor in the microphone connector for the MH2. 
> Small area to play in, but it gets it out of the way. The down side is 
> the need to pull power from the K2 out to the connector. I have learned 
> that the mic power pin is a prime intrusion point for RFI.
> 
> On Apr 6, 2007, at 5:03 AM, Don Wilhelm wrote:
> 
>> Dave,
>>
>> Since your plan is to use both the MH2 and the Heil headset with the 
>> HC-5 element, I strongly recommend that you jumper the K2 mic 
>> configuration header for the MH2 - all pins jumpered straight across 
>> (use the little configuration jumpers for computer headers) and solder 
>> a 5600 ohm resistor across pins 1 and 6 of the mic jack.
>>
>> You might also consider connecting the headphone audio to pin 5 of the 
>> mic jack - leave the jumper off the header pin 5 and connect the audio 
>> to the header pin marked "5" with no connection to the pin marked "FUNC"
>>
>> Then for the Heil headset, build a preamp/adapter in a small external 
>> enclosure - the headset plugs into the adapter.  You will need a 
>> preamp to successfully use the Heil HC5 element.
>>
>> I have a schematic (it is a bit cluttered, but usable) for a preamp 
>> that was designed just for that application - unfortunately I cannot 
>> attach it to the reflector post, so I will send it to you separately.
>>
>> 73,
>> Don W3FPR
>>
>> David Wilburn wrote:
>>> I have a Heil headset that I purchased about 4 years ago.  I'm not 
>>> sure if it is the "pro" or not.  As memory serves, at the time, the 
>>> next step up had a dual element with a switch.  The headset has an 
>>> HC-5 element. I have an adapter to this to connect to my recently 
>>> sold, since finishing my base K2, Kenwood TS-570D(G).  I have also 
>>> purchased an MH2 microphone.
>>> The original plan was to sell a different radio, (IC-718) and keep 
>>> the TS-570 and thus the headset.  The plan then was to use the MH2 
>>> for the K2.  I will still be using the MH2 primarily for the K2.  But 
>>> I want to be able to use the headset on occasion as needed.
>>> I understand the instructions for wiring up the MH2 on the K2.  How 
>>> will this impact the use of the headset?
>>> This email suggests it only needs straight across jumpers.
>>> http://www.ac6rm.net/mailarchive/html/elecraft-list/2003-01/msg00598.html 
>>>
>>> If that is the case, and I do have the Kenwood adapter already, then 
>>> if I just put the straight jumpers in, I should be fine.
>>> If I want to use the MH2, then I need to either put the resistor in 
>>> the microphone somehow (not something I am looking to tackle with my 
>>> large hands) or make an adapter cable for the MH2 that has the 
>>> resistor in it.
>>> Am I barking up the correct tree hear, or chasing a feral goose?
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> 
> - Jack Brindle, W6FB
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