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 Post subject: Bought a Unmolested D104 for the Rigs--Restoration Tips ?
PostPosted: Dec Sat 05, 2020 4:15 pm 
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back in the day, i sold my d104 and could kick myself in the hind end, but with that said, i got a nice price for it.

anyway, i was able to find a very nice unmolested 104 on the internet. it is amazing how many of them are bastardized with all sorts of kitchen table technicians modifications.

i don't need a silver eagle or one of the fully chrome ones as the prices of them are out of sight. i got the basic TUG8 stand. besides, i won't want to touch the all chrome one and get it fingerprinted up.

other than changing the capacitors on the little amp board, taking it apart to clean the switch, mic grill, wires in the 4 pin connector, and everything, are there any other tips or things that i should be looking at during the restoration ?

my microphone is seen here.

https://www.ebay.com/itm/313320995985#rwid

i was going to get one of the new hand held or desktop astatic mics, but reviews said how bad they are when it comes to the cheesy garbage PTT switch. they are not made in ohio anymore and are nothing but cheap imported asian garbage.

steve

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Sat 05, 2020 6:49 pm 
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What transmitter are you using with it? The amp board may not be needed or desirable. Boat Anchors like my Viking II do not need it.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Sun 06, 2020 2:13 am 
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Location: Newton, MA 02465
Quote:
What transmitter are you using with it? The amp board may not be needed or desirable. Boat Anchors like my Viking II do not need it.


Years ago [why, oh why, did I sell this rig!??], I used a D104 with a Johnson Valiant and ... ditto ... no preamp necessary.

Back story: Probably 30 years ago, a local senior ham was seriously down-sizing in preparation for selling his home in
the next town. He posted an ad in the local Want Advertiser for the Valiant, a Hammarlund HQ-180, the Johnson
SSB adaptor for the Valiant, and the D104, all for $300. Sold it all a few years later after buying a used Kenwood TS-830 at the
Deerfield (NH) flea market. Not that I really had space for that classic rig, but still kick myself sometime for selling
it.

Cheers -

Bruce K1FFX


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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Sun 06, 2020 5:47 am 
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So, what rig are you going to use this mic with?

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Sun 06, 2020 2:46 pm 
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To know what to do we have to know what the load impedance will be. Vintage ham rigs from the 1950s have tube preamp stages. An unamplified crystal element works best i.e. no preamp needed and it can be bypassed. The grid resistor on the audio input to the rig can be 10 megohms to get the widest frequency response from the xtal element.

Is the element good? one quick test is to put the mic directly into the vertical input on an oscilloscope. The element alone will generate enough voltage to drive the scope with audio with the v./div switch down in the low range.

If the rig is modern, the preamp may be needed. It's really more of a matching circuit to modern low Z loads. W9AC has a better design. It's all on his QRZ page.

Why is the mic head black?


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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Sun 06, 2020 6:36 pm 
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Any thing greater than about 3 Meg Ohms is fine for bass response as you can see from the chart below.

Image

I use one for my test mic on old transmitters, because some old transmitters don't even have PTT, but a separate Tx/Rx switch, I installed a switch on the base so I can swap Mic audio or PTT, to the tip of the mic's 1/4" stereo plug.

Image

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Sun 06, 2020 7:10 pm 
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If it is a TUG base then the load resistance is not relevant.

The preamplifier has a gain pot in the D-104 base.

Personally, I use a modified D-104 with an electric element and a K7DYY version II processor board installed in the mike's base. output level is easily adjusted from 0 dBm down to lower level as needed.

The important question is what radio are you going to be using the mic with? For almost any CB the TUG-6 base will be fine. Unless you want Hi-Fi sounding AM I'd trying it as is.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Sun 06, 2020 8:16 pm 
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It's not a D-104, but I am using an old Turner +2 amplified microphone on the Ten-Tec Omni V. I keep the send level on the microphone preamp turned down to about one-third of the rotation, and adjust the modulation level on the rig so that the ALC indicator LED just flickers. On-air reports have been good.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Mon 07, 2020 4:10 am 
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i am using it with a brand spanking new Galaxy 2547 base cb.

also, it will be used on a Cobra 148, both are SSB and stock.

steve

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Tue 08, 2020 6:47 pm 
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it arrived today. i will clean the switch, control, replace the capacitors if they are electros, wash the fabric wind screen, and polish it up.

steve

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Tue 08, 2020 6:59 pm 
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Solid state radios, leave the amp. It has alot more output than you need and will have to turn it down alot. But the transistor rigs will not present a good match to the crystal or ceramic element straight up. You would want at least half a meg input impedance and a full meg or more is better. Most of the transistor radios are made to work with either a matching mic or a 500 ohm dynamic type. Plus, used 104's are notorious for having weak or dead elements, in the case they are the rochelle salts that absorb moisture over time and are easy to damage otherwise. The ceramic elements are much more durable. Some later ones used a ceramic element. I agree with others that you are rolling the dice buying old used ones to a large extent. I got two heads with good elements, the last time I tested them, and have had alot that were shot or poked full of holes by sticking needles in the grille. CBers urban legend went around that it improved the sound. Till the humidity gets inside. I saw at least one that looked like shotgunned.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Tue 08, 2020 7:48 pm 
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amp stays.

when the element goes south, is it all or nothing ?

i will ck it on an audio tracer and on the talkback on the radio.

steve

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Tue 08, 2020 8:00 pm 
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wazz wrote:
Solid state radios, leave the amp. It has alot more output than you need and will have to turn it down alot. But the transistor rigs will not present a good match to the crystal or ceramic element straight up. You would want at least half a meg input impedance and a full meg or more is better. Most of the transistor radios are made to work with either a matching mic or a 500 ohm dynamic type. Plus, used 104's are notorious for having weak or dead elements, in the case they are the rochelle salts that absorb moisture over time and are easy to damage otherwise. The ceramic elements are much more durable. Some later ones used a ceramic element. I agree with others that you are rolling the dice buying old used ones to a large extent. I got two heads with good elements, the last time I tested them, and have had alot that were shot or poked full of holes by sticking needles in the grille. CBers urban legend went around that it improved the sound. Till the humidity gets inside. I saw at least one that looked like shotgunned.


My luck sucked. Bad element in mike, bad NOS spares in the factory box at an estate sale!! They did not survive damp environments.... A miketopsy showed the Rochelle salts had turned to mush. I ended with an electret element and called it a day. There is an expensive Heil cartridge that some folks use, but I think the price is a bit steep.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Tue 08, 2020 8:42 pm 
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have a link to the electret element if i need one ?

the mic is pristine, but will set until i get my afternoon nap in.

will report back on electrical condition later.

steve

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Tue 08, 2020 11:35 pm 
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D-104 high impedance (no amp) are great on Ham tube type AM transmitters. So are most ceramic or crystal type elements. The much more common high impedance dynamic mics for the most part do not have enough high frequency response.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Wed 09, 2020 2:28 am 
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Well unless the element is dead from abuse, they will often get weaker for awhile till the output is unusable. You will probably see slight variations in output a couple dB even among "good" elements. The amp in the base will obviously compensate for weakness up to some point. And some of the "substitute" smaller elements that people say will work in those mics, will work. But not sound the same at all. Just never touch the thin aluminum diaphram. It will dent easily. They have fibreglass pads on the front of the elements which is apparently to modify the sound and should be retained. Damping or something? I once repaired one by dissecting a damaged element and extracting the crystal and implanting in one that was dead, but it is a bit tricky and delicate work, not something I would want to do again. Here is a well known upgrade for the mic-
https://www.ebay.com/it Different people selling on ebay. Now others sell similar kits on there. IF you had an old Radio Shack blister pack electret element, the ones that sold for 1.59$, or a known good element out of anything but a crummy teensy cellphone mic, you could do it yourself. You would need to retain the battery holder in the base and supply a biasing resistor and a DC blocking cap to couple the audio in to the radio. Unless it is a modern rig like Icom that supplies DC on the audio line to the mic. But the kits would have all the stuff, and good instructions, I would assume. As time progresses over the years there will be fewer and fewer of these with still good elements. But sometimes they can last a real long time. I have a 40s or 50s Electrovoice that is a crystal mic and it works fine, still. Not having seen it new, I cannot say if it has lost any output though. For laughs, this guy put together a D-104 "Frankenmic" from junk and wants a princely sum. https://www.ebay.com/itm/Vintage-Ring-S ... SwzEpfxoq~ I have a 30s head made for ring suspension but it is dead. The early ones just had a threaded stud tube for stand mounting.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Wed 09, 2020 5:16 am 
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i have fantastic audio out of it.

i tested it with an audio tracer.

the mic is all shined up and is just perfect and i replaced the 4.7 mfd lytic in there also.

the element diaphragm was all pulled away from the frame the whole way around the MC-320 black housing. i carefully moved it aside as the two wires to the crystal element gave a lot of play, applied a very thin coating of contact cement to the lip where the diaphragm recesses into the plastic, and presto, all is just perfect.

i will rewire the 4 pin connector on it tomorrow, slip on the boots, and do some talking.

i also will get one of the spare crystal elements (new production) to have on hand to retrofit in it someday.

i am not so sure that i want to mess with an electret element.

steve

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Thu 10, 2020 1:43 am 
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the mic works like a champ. i was blowing the doors out around here.

i think i will buy the electret three element retrofit kit to have for a spare.

steve

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Thu 10, 2020 2:36 am 
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Dutch Rabbit wrote:
the mic works like a champ. i was blowing the doors out around here.

i think i will buy the electret three element retrofit kit to have for a spare.

steve

Your Astatic element will likely out live you. You do not need the spare element that will sound different anyways.

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 Post subject: Re: Bought a Unmolested D104 for the Rigs--Restoration Tips
PostPosted: Dec Thu 10, 2020 3:21 am 
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thx.

steve

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