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Yet another D104 mic wiring question.

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Reuben Popp

Yet another D104 mic wiring question.

Hey everyone, quick question.

I built my K2 over seven years now and just realized I had never completed
the mic section. Granted, I didnt have my ticket at the time, so...

Anyway, I recently picked up a d104 mic with a T-UG8 base (the one with the
adjustable preamp in the base). I have not really verified the wiring in
the base; it looks rather poor in parts, like someone did it with a dirty
iron tip or whatnot but otherwise looks okay.

The mic came with an old four pin connector. The cord itself has three
wires plus the copper braid/shield: black, red, and white. In wiring it
to a standard eight pin female, white went to pin 1, red to pin 2, copper
braid to pin 7, and black to pin 8. On the P2 jumper, I jumpered it as per
the KSB2 manual for Kenwood for AF, PTT, and the two grounds.

That said, on keying the mic, the K2 goes silent but there is no evidence
on the S meter that anything is happening. FWIW I have replaced the 9v
battery in the base and attempted the same after adjusting the preamp pot
to each extreme. Do I need to jumper the other pins on P2 as per the KSB2
instructions? Do I have the female connector wired correctly? Or perhaps
I should revisit the wiring on the preamp and make sure someone else didn't
Bubba it in the past...

Any hints, suggestions or help would be most appreciated.
Reuben
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Bob McGraw - K4TAX

Re: Yet another D104 mic wiring question.

There's several ways the wiring in the mike base can be done. There's
two switches associated with the grip-to-talk bar on the T-UG8 base. I
suggest, if not on the inside of mike base, you GOOGLE Astatic D-104
and get a schematic. You will need to use the amp in the base in as
much as the K2 mike input Z is much too low for the mike element. Thus
the amp serves as an emitter follower with gain to provide a proper Z
for the mike element and drive the lower Z provided by the K2 mike
input. {The D-104 element likes to see 3.0 megohms to 4.7 megohms
input Z.}

The mike cable will have two conductors which will be the PTT circuit
and a shielded conductor for the audio.

Schematics will be of great help in figuring out what needs to be done
in terms of wires connected to the terminal strip in the base of the mike.

73
Bob, K4TAX

On 11/1/2015 9:30 PM, Reuben Popp wrote:

> Hey everyone, quick question.
>
> I built my K2 over seven years now and just realized I had never completed
> the mic section. Granted, I didnt have my ticket at the time, so...
>
> Anyway, I recently picked up a d104 mic with a T-UG8 base (the one with the
> adjustable preamp in the base). I have not really verified the wiring in
> the base; it looks rather poor in parts, like someone did it with a dirty
> iron tip or whatnot but otherwise looks okay.
>
> The mic came with an old four pin connector. The cord itself has three
> wires plus the copper braid/shield: black, red, and white. In wiring it
> to a standard eight pin female, white went to pin 1, red to pin 2, copper
> braid to pin 7, and black to pin 8. On the P2 jumper, I jumpered it as per
> the KSB2 manual for Kenwood for AF, PTT, and the two grounds.
>
> That said, on keying the mic, the K2 goes silent but there is no evidence
> on the S meter that anything is happening. FWIW I have replaced the 9v
> battery in the base and attempted the same after adjusting the preamp pot
> to each extreme. Do I need to jumper the other pins on P2 as per the KSB2
> instructions? Do I have the female connector wired correctly? Or perhaps
> I should revisit the wiring on the preamp and make sure someone else didn't
> Bubba it in the past...
>
> Any hints, suggestions or help would be most appreciated.

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Reuben Popp

Fwd: Yet another D104 mic wiring question.

In reply to this post by Reuben Popp

Whoops, meant this to go the reflector (sorry Don!) :)

A little bit of progress.... maybe.

I went ahead and rewired the T-UG8 base back to the original schematic to
ensure that it was as "stock" as could be. I also noticed that the
original crystal element (under the insulating material) looked like
someone pushed it in some (and it had a small pinhole). I decoupled it and
replaced it with a Shure 99E86 element that I had lying about.

On the radio side of things, I went through the KSB2 alignment procedures,
just to be sure. SSBA is set to a 3, SSBC is set to 2:1 (at least I think
that's right.. the manual and radio is in the garage). Last but not least,
I also turned the D104 5K pot to a hair above its bottom extremity. Now
blowing or whistling or just plain talking into the mic will cause the K2
to cut out with a slight bzzt*pop* [from the radio] as the s-meter goes all
the way to the right and then goes dark. This happens every time.

That said, that Shure element is medium impedance as far as I know, about
300 ohms IIRC. At that point, can I (or should I?) completely bypass that
preamp? Can anyone provide an example schematic on the routing without the
preamp? Is it safe to just use the schematic from the unamplified UG8 base?

Thanks again to all and 73

Reuben

On Nov 4, 2015 9:32 AM, "Don Wilhelm" <[hidden email]> wrote:

> Reuben,
>
> You have it wired correctly. Pins 7 and 8 are connected together in the
> K2.
> Does the K2 go into transmit when you close the PTT switch? If so, that
> part is good.
> You may want to check continuity from the mic base to the plug for the
> white (AF) and the Shield (AF return or MIC GND, just to assure yourself
> that the mic cable is intact.
>
> Another continuity check that you can do is between the white wire in the
> base of the mic (with the mic plugged in) to KSB2 P1 pin 5 - that will
> verify that both the mic cable and the K2 wiring for the AF signal is
> correct and intact.
>
> 73,
> Don W3FPR
>
> On 11/4/2015 10:10 AM, Reuben Popp wrote:
>
> Hey Don,
>
> I had replaced the original four pin connector with an eight pin according
> to a post I found online for a Kenwood TS-440:
>
> 1 - MIC
> 2 - PTT
> 3 - DOWN
> 4 - UP
> 5 - NC
> 6 - NC
> 7 - MIC-GND
> 8 - COMMON (PTT GND)
>
> "The mic came with an old four pin connector. The cord itself has three
> wires plus the copper braid/shield: black, red, and white. In wiring it
> to a standard eight pin female, white went to pin 1, red to pin 2, copper
> braid to pin 7, and black to pin 8. On the P2 jumper, I jumpered it as per
> the KSB2 manual for Kenwood for AF, PTT, and the two grounds."
>
> It's quite possible I might have goofed something up here, but I *believe*
> I have it set correctly. The only thing I can think of is that maybe I
> have the mic ground and PTT ground swapped? Is the copper braid the PTT
> ground?
>
> Thanks again and 73
> Reuben
>
> On Wed, Nov 4, 2015 at 8:29 AM, Don Wilhelm <[hidden email]> wrote:
>
>> Reuben,
>>
>> You only need 4 jumpers on the K2 Microphone Configuration Header - AF to
>> 1, PTT to 2, and ground at pins 7 and 8.
>>
>> Since you found that the microphone wiring had been altered, have you
>> checked the wiring from the mic base to the 8 pin plug?
>> the AF should connect with pin 1, PTT connects to pin 2. Connect the AF
>> return to pin 8 and the PTT return to pin 7.
>>
>> Do you have a Kenwood microphone or can you borrow one from a fellow
>> ham? That no-name microphone will likely work if you wire the mic plug
>> correctly.
>> See if that microphone works on your K2. That test will tell you whether
>> to look in the K2 or into the microphone for the problem.
>>
>> 73,
>> Don W3FPR
>>
>> On 11/4/2015 9:13 AM, Reuben Popp wrote:
>>
>>
>> Just as a followup, at the time I didn't have enough jumpers to put one
>> on every set of pins on the mic header. Is that my issue here? If so,
>> that part wasn't overly clear in the KSB2 instructions, at least to me, lol.
>>
>> Other than that, I'm running out of ideas here. I have a no-name dynamic
>> hand mic from a parts bin that I will wire up tonight to see if that works,
>> but after that....
>>
>> The only other thing that I can think of is maybe one of the components
>> in the base is bad, whether it's the pot, the switch or something on the
>> amp board.
>>
>> Thanks again to all and 73
>> Reuben
>>
>> On Mon, Nov 2, 2015 at 6:17 AM, Don Wilhelm < <[hidden email]>
>> [hidden email]> wrote:
>>
>>> Reuben,
>>>
>>> You have the mic configuration header wired correctly. Any chance that
>>> the potentiometer in the mic is set to its low point?
>>> I suspect that microphone. Many of the amplified D-104 mics have had
>>> the preamp in the base modified.
>>> As a test, see if you can borrow a Kenwood dynamic microphone from a
>>> local and see if that works.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>>
>>> On 11/1/2015 10:30 PM, Reuben Popp wrote:
>>>
>>>> That said, on keying the mic, the K2 goes silent but there is no
>>>> evidence
>>>> on the S meter that anything is happening. FWIW I have replaced the 9v
>>>> battery in the base and attempted the same after adjusting the preamp
>>>> pot
>>>> to each extreme. Do I need to jumper the other pins on P2 as per the
>>>> KSB2
>>>> instructions? Do I have the female connector wired correctly? Or
>>>> perhaps
>>>> I should revisit the wiring on the preamp and make sure someone else
>>>> didn't
>>>> Bubba it in the past...
>>>>
>>>>
>>>>
>>>
>>
>>
>
>

Bob McGraw - K4TAX

Re: Fwd: Yet another D104 mic wiring question.

Seems like RF getting back into the mike or mike circuit. Be sure the
Red & Blue wires in the UG8 cable to the radio are correctly wired to
the switch on the inside of the base, grip to talk bar switch, and the
Black & White & Shield which are the audio are correct to the mike
connector for the radio. Also try the radio on a dummy load. If it
works correct with the dummy load, then sure bet, it is an RFI issue.
That needs to be corrected.

If you are using a medium impedance {what ever that is} element, the
internal preamp in the UG8 base should not be needed. There's several
wiring diagrams on the internet, find one and wire the base
accordingly. Personally, unless one is using an original D-104
element, which requires a very high load impedance in the order of 3
megohms or more, then the "preamp" in the base is not needed and is
often more problematic than useful. If you are using the original
D-104 element, then the preamp is necessary in order for the mike
element to see a proper impedance and the preamp will drive a lower
impedance such as found in today's radios. But in other words "more
crap = more problems".

I find this site to have good information regarding the D-104 and the
UG8 stand and how to wire the "make before break switch" and the "break
before make switch". http://www.qsl.net/wa2mzf/d104.html
<http://www.qsl.net/wa2mzf/d104.html>

73
Bob, K4TAX

On 11/8/2015 10:13 PM, Reuben Popp wrote:
> ast,
> I also turned the D104 5K pot to a hair above its bottom extremity. Now
> blowing or whistling or just plain talking into the mic will cause the K2
> to cut out with a slight bzzt*pop* [from the radio] as the s-meter goes all
> the way to the right and then goes dark. This happens every time.

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Reuben Popp

Fwd: Fwd: Yet another D104 mic wiring question.

Ugh... did it again. To the reflector!

---------- Forwarded message ----------
From: Reuben Popp <[hidden email]>
Date: Mon, Nov 9, 2015 at 6:05 AM
Subject: Re: [Elecraft] Fwd: Yet another D104 mic wiring question.
To: Bob McGraw - K4TAX <[hidden email]>

G'mornin Bob,

The cord on the base is only four wires: black, red, white and shield.
Note this is a T-UG8 base.. I think the UG8 was the unamplified base? I
don't know if either had a cord with more than the four wires; I know my
T-UG9 base does. Internal to the base itself there is a blue wire, as
detailed in http://www.rollanet.org/~rrars/tech_files/d104_manual.pdf.
That is exactly how the mic is wired now. The only thing I did not rewire
is the leaf switches as they appeared unmolested. I will take a look at
those tonight as I wanted to check their contacts anyway. In the old
electromechanical pinball machines, those things would oxidize fairly
quickly, so I thought it would be good to check here anyway. I will also
give it a whirl with a dummy load. I only have the small dummy load kit
from Elecraft... I assume that will be okay?

I'll also take a look at bypassing or just flat out removing the preamp
circuit.

Thanks again and 73
Reuben

On Mon, Nov 9, 2015 at 5:33 AM, Bob McGraw - K4TAX <[hidden email]>
wrote:

> Seems like RF getting back into the mike or mike circuit. Be sure the
> Red & Blue wires in the UG8 cable to the radio are correctly wired to the
> switch on the inside of the base, grip to talk bar switch, and the Black &
> White & Shield which are the audio are correct to the mike connector for
> the radio. Also try the radio on a dummy load. If it works correct with
> the dummy load, then sure bet, it is an RFI issue. That needs to be
> corrected.
>
> If you are using a medium impedance {what ever that is} element, the
> internal preamp in the UG8 base should not be needed. There's several
> wiring diagrams on the internet, find one and wire the base accordingly.
> Personally, unless one is using an original D-104 element, which requires
> a very high load impedance in the order of 3 megohms or more, then the
> "preamp" in the base is not needed and is often more problematic than
> useful. If you are using the original D-104 element, then the preamp is
> necessary in order for the mike element to see a proper impedance and the
> preamp will drive a lower impedance such as found in today's radios.
> But in other words "more crap = more problems".
>
> I find this site to have good information regarding the D-104 and the UG8
> stand and how to wire the "make before break switch" and the "break before
> make switch". http://www.qsl.net/wa2mzf/d104.html <
> http://www.qsl.net/wa2mzf/d104.html>
>
> 73
> Bob, K4TAX
>
> On 11/8/2015 10:13 PM, Reuben Popp wrote:
>
>> ast,
>> I also turned the D104 5K pot to a hair above its bottom extremity. Now
>> blowing or whistling or just plain talking into the mic will cause the K2
>> to cut out with a slight bzzt*pop* [from the radio] as the s-meter goes
>> all
>> the way to the right and then goes dark. This happens every time.
>>
>
> ______________________________________________________________
> Elecraft mailing list
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>
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>