disconnecting antennas

[Greg Derda-2]

I am pretty sure that there are a couple of very simple circuits in
"W1FB's Design Notebook" that specifically use the "D104 ->
modern_radio" as an example.

Greg
KI4MMM
K2 #6100

On Sep 6, 2007, at 1:29 PM, Don Wilhelm wrote:

> John,
>
> If your D104 is an older one with the high impedance crystal or
> ceramic element, yes it will not work so well (if at all).
>
> There was an article in QST about a year ago with a circuit design
> that had a very high impedance input and the low impedance output
> required by modern day radios, although a transformer with the right
> ratio should work too.
>
> Another alternative is to change the element in the D104.  Heil offers
> a kit to do just that - check www.heilsound.com for info.
>
> My D104 with an HC5 element draws comments from time to time.
>
> 73,
> Don W3FPR
>
> John Huggins wrote:
>> Thanks for the information all.
>>
>> So...
>>
>> I guess hooking up a D104 straight to K2 is not going to work out so
>> well.  Yes I know this is like putting tail fins on a Ford Taurus,
>> but the kids really dig talking into a mic like that during times we
>> promote ham radio.
>>
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[John Huggins]

Thank you for the hints.

Thanks to your and other's comments on the Elecraft list I have found
numerous good examples with some as minimalistic as a FET + passives all
the way to a good Instrumentation Amp + passives.

This has inspired me to create a circuit based more on the modern In-Amp
method leaving the only question of what the input impedance and range
of typical radio mic inputs.  Plus a survey of what voltage and current
are available on the mic connector helps design for the most radios.

In support of this I am scoring some wins on D104 mics on Ebay which are
available on the cheap.

Fun stuff... perhaps I will make this available as a "kit" for fellow
D104 freaks.

John


Greg Derda wrote:

> I am pretty sure that there are a couple of very simple circuits in
> "W1FB's Design Notebook" that specifically use the "D104 ->
> modern_radio" as an example.
>
> Greg
> KI4MMM
> K2 #6100
>
> On Sep 6, 2007, at 1:29 PM, Don Wilhelm wrote:
>
>> John,
>>
>> If your D104 is an older one with the high impedance crystal or
>> ceramic element, yes it will not work so well (if at all).
>>
>> There was an article in QST about a year ago with a circuit design
>> that had a very high impedance input and the low impedance output
>> required by modern day radios, although a transformer with the right
>> ratio should work too.
>>
>> Another alternative is to change the element in the D104.  Heil
>> offers a kit to do just that - check www.heilsound.com for info.
>>
>> My D104 with an HC5 element draws comments from time to time.
>>
>> 73,
>> Don W3FPR
>>
>> John Huggins wrote:
>>
>>> Thanks for the information all.
>>>
>>> So...
>>>
>>> I guess hooking up a D104 straight to K2 is not going to work out so
>>> well.  Yes I know this is like putting tail fins on a Ford Taurus,
>>> but the kids really dig talking into a mic like that during times we
>>> promote ham radio.
>>>
>> _______________________________________________
>> Elecraft mailing list
>> Post to: [hidden email]
>> You must be a subscriber to post to the list.
>> Subscriber Info (Addr. Change, sub, unsub etc.):
>> http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/subscribers.htm
>> Elecraft web page: http://www.elecraft.com
>>
>
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>

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