Re: {Collins} Circuit info wanted

I should remind everyone sorta tongue in cheek:

One of the reasons that we love our Collins is the way it sounds. This is a
result of very careful audio tailoring, design and matching the
characteristics of the mechanical filter. There is just that "Collins
Sound". The more we mess with the audio input characteristics and the
amplified (and therefore more tailored and distorted audio - any amplifier
adds more distortion), the further we get from the "Pure Life".

Second.....a CB microphone ???  Really ??

OK, I will go back in my hole and work on my avionics display and the Q4
issue.....which, by the way, has no CB stuff in it.  :-)


-----Original Message-----
From: Collins [] On
Behalf Of wb9tow
Sent: Tuesday, November 04, 2014 8:21 AM
To: Garey Barrell; COLLINS
Subject: Re: {Collins} Circuit info wanted

Oh, and to modify the input Z of the AF amp, remove the 1 Meg to ground at
the grid and install a 4 Meg To Ground. ..

Sent from my Verizon Wireless 4G LTE smartphone

-------- Original message --------
From: Garey Barrell <k4oah@xxxxxxxxxxxxxx>
Date:03/11/2014  22:50  (GMT-05:00)
To: COLLINS <collins@xxxxxxxxxxxxx>
Subject: Re: {Collins} Circuit info wanted 

The only problem with the amplified version of the D-104 is with people who
run the gain too high for their radio to take.  The D-104 is a crystal (or
ceramic) cartridge which has a volt or more of output  _into a very high
impedance_  load, like a Megohm or more.  This is fine with tube type rigs,
but modern radios (mostly solid state) are designed for a low impedance
microphone with much lower output.

The amplifier was added by Astatic to allow the microphone to work with
newer radios, mostly CB type.  Therein lies the rub.....  CB types think
that the higher the gain, and the louder they talk, the louder their signal
will be.

The amplifier provides the Hi-Z load that the cartridge wants to see, and
has a Lo-Z output to drive any radio, Hi -OR- Lo Z.

Most tube type radios will work fine with the 'bare' D-104, although they
will sound better with another Megohm or so resistor in series with the
cartridge.  If your mic has the amplifier, just set your transmitter GAIN
control to where you set it with other microphones, then start at minimum
gain in the MIC preamp.  While talking normally into the MIC as you usually
do, increase the gain on the MIC preamp until you get the desired modulation
level.  Works just fine........

73, Garey - K4OAH
Glen Allen, VA

Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs

Michael victor R wrote:
> John:
> all that I have read says do NOT use an amplified mic on Collins. 
> Although I have a bunch of Astatics I do Not have a "K" but I only buy 
> junk that I can rebuild to good working microphone and ironically I have
not seen that.
> Have fun! good luck
> mike K9LSH.
> On Thu, Oct 30, 2014 at 3:25 PM, Garey Barrell <k4oah@xxxxxxxxxxxxxx>
>> John -
>> I don't have a schematic, but the 'function' of the 'K' version is 
>> that it sends either a CW letter 'K' or a multi-tone burst at the end 
>> of transmission.  "In other words, 'K' ".  Apparently popular amongst 
>> the CB crowd.
>> 73, Garey - K4OAH
>> Glen Allen, VA
>> Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement 
>> CDs <>
>> John Clare wrote:
>>> I have tried unsuccessfully previously to obtain circuit information 
>>> regarding "K" versions of Astatic D 104 microphones.
>>> I have details for most other versions of the D 104 Crystal Mics but 
>>> K info seems to be shrouded in secrecy. Are there any Collins owners 
>>> out there that have repaired or adapted K versions?
>>> I have a lovely Night K Eagle that needs repairing prior to use with 
>>> my KWM-2A.
>>> John Clare VK1CJ.

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