[Elecraft] Heil Headset HC-5

Fri Apr 6 21:33:33 EDT 2007

OK, just for clarification and to set the record straight, my K2  
(#2905) had NOT had R14 or any other component changed in the SSB  
audio path. I use my Heil headset (HC-4) plugged directly into the  
KRC2, no preamp, no mods. 438 QSOs in last November's phone Sweepstakes.

It seems to work for me...

Note the important part of my original post. Mine is a K2/100, so the  
RF section can make up for any low audio. SSB at 5 watts needs all  
the help it can get, so a preamp is probably a good idea. That's not   
a knock against QRP - as my friend, QRP GURU N6WG will attest, I am a  
fan. I just don't want to be frustrated in a contest with that power  
level, especially when everyone around me is running a gallon or so...

On Apr 6, 2007, at 8:33 AM, Don Wilhelm wrote:

> 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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- Jack Brindle, W6FB
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