Astatic D-104 Rebuild & Update To Condenser Microphone 

Wow... that is brilliant how the bases are labeled. Complicated enough and makes sense enough that I may be able to remember it. Thank you. Merry Christmas and a truly safe and healthy New Year. My wife and I were Mr. and Ms. Santa tonight for the make a wish foundation. It was great.

I feel blind if I can't see my transmission on a scope. Interesting that we strive for sharp peaks to ensure fidelity but if one boosts the treble and bass like on an iCom 7300 and add in just a little compression (set at 2) it not only will have more power but the receiving end will like it better. In this case, I notice a bit of rounding (not clipping) of the tips of the oscilloscope display.

They can be rebuilt! I do it often. Sometimes change them to ceramic within the original element, other times I fit a brand new crystal packet.

Truly a "timeless design" as the saying goes and can be repaired and put back to use in so many ways for not much money. The one I showed in the video had the battery popped and it was a bit of a mess but taking it all apart and running it thru the dishwasher was a good start to cleanup. 73

I am not sure 5 volts is recommended. Mostly it seems to be 9 volts to 48 volts, depending on the microphone element. Are you sure it it 5V coming out of your radio? It may work OK with 5V, I can't say for sure.

I don't know anything about adding a resistor to the original crystal or ceramic microphones to give a better low-end. I can't see how that would work but they may have a method I am not familiar with. The vintage microphone elements do tend to get weaker and higher pitched with less energy in the output. I have one that still works OK and I have a friend that uses an original element and communication is good but the vast majority of the old elements are very weak and not usable. As I believe I mentioned in the video, the D-104 stands with the battery clip are perfect for a condenser mic repair/upgrade. I do not use the preamp. I have even put three microphone elements in parallel mounted in the head. Seems there is a slight improvement in it but it may just be my imagination. I guess my message here is that these old microphones are so well built and classic, it is cheap and easy to keep them running another 50 years and beyond... lastly, I will say that my ear responds to higher-pitched sounds better than bassy sounds and gets thru QRM better than low-pitched voices so I don't run the HiFi versions of microphones like some guys do and I run zero to very little speech compression and processing. Just my preference. Thanks for your comments. I hope it helps keep your magnificent D-104 microphones running for a long time. 73

@@ElPasoTubeAmps very good.. and well put. I know the crystal over time does loose some of it's shine (for the lack of a better word). Personally I wouldn't want to go slapping resistors around in a good working Astatic lol. I'm looking at that M2 by Delta.. seems to be a good mic? I'm glad you posted your ebay site.. your in my favorite sellers list now. One of these days I'd like to get one of your 'puck conversions'. Others say they work well. Thanks for the reply... I learned a lot watching... 3's

I have had good luck with this one. www.ebay.com/itm/353737798123

The old tube transmitters do have a very high gain input circuit. Most all use a 12AX7 and as you mentioned, even low output dynamic mics can sound good. The old D-104 elements put out something like 100-200 mV and could really drive a speech amplifier to a loud volume. The electret microphones of today will put out the same voltage range so they are good like the old crystal/ceramic mics of yesteryear but they need a voltage to operate the FET amplifier built right into the little mic element. Pretty much every modern day tranceiver has that voltage for the electret microphone built right into the unit but the old units like the Collins and many others need an external voltage like a 9V battery to supply the voltage. If there are enough contacts in the mic to operate PTT plus turn the voltage on and off to the mic element during transmit and off during receive, the 9V battery will last for years. Right after making this video, I built an outboard voltage source and variable load so I do not have to have a battery in every microphone. I just change the bad element out in the mic head and plug it into the little chassis box and it supplies the 9V. Maybe a video of that would help others where the mic does not have a convenient battery holder in the bottom. Thanks for your comments.

@@ElPasoTubeAmps Thank you very much for the explanation, Probably AM transmitters are very demanding, they need a strong modulating signal. SSB is much preferable. In my cheap CB AM, for good modulation it needs an electret microphone and at least one transistor amplifier. We used to connect it to a friend and the Amateur SSB radio was heavily loaded with modulation. CB radios like midland 77-092 are very insensitive to modulation and are difficult to control, probably have low input resistance to the microphone. These old radios like yours are wonderful. I love to look at those analog scales, nicely lit with incandescent bulbs. It is a pity that there are no such ones anymore. Health for you, the movies are great, I watch them with pleasure.

I have found that repairing or upgrading vintage microphones is easiest done with the inexpensive condenser microphone elements. You can get ten for $6.90 off Amazon (69 cents each...) Modern day radios with the "phantom" voltage built into the radio and supplied to the microphone, makes this easy. As for older microphones like the D-104, if it has the 9V battery holder and the preamp in the base (I remove the preamp and do not use it) the upgrade to the condenser type microphone is very easy and inexpensive also - probably $3 in parts - is the way to go and they work great and sound good on modern radios and vintage radios like the Collins S-Line vacuum tube equipment. I have a Turner desk mike that I changed to a condenser element, which I believe was originally a dynamic microphone element. The condenser mic must be turned-on and turned-off from the 9V battery with each push of the PTT switch or it will run the battery down in just a few days if left on all the time. Not all microphones have the extra contacts to so this so I have had to use very small, low current, relays in the base of the microphone along with finding a place to mount the 9V battery. Hope this helps. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ZZ5J9D5APsw.html&lc=UgyrzivdRrQ110jjB_p4AaABAg

I have had good luck with this one. www.ebay.com/itm/353737798123

@@ElPasoTubeAmps Thank you for the expeditious reply, have a most awesome weekend!

Here is a link to the wiring diagrams. Just search for, Astatic D104 Wiring Diagram and you should find lots of help. www.google.com/search?q=astatic+d104+wiring+diagram&sca_esv=570067020&source=hp&ei=e-gaZfLnHa-nqtsPhaePwAQ&iflsig=AO6bgOgAAAAAZRr2iwC-MPx5f3d-1u1ZOsBSumtfuRg7&oq=Astatic+wiring+diagram&gs_lp=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&sclient=gws-wiz#vhid=-c7OsS_asEqp7M&vssid=l

Do you have a diagram of hoe th wires are connected on the 8 pin base? 8 -purple from potentiometer 7-shield from mike neck 6-brown 4-red from cable and other red from neck 3-black from cable and clear blue from neck 2-blue from neck 2-white from neck still need to connect dark green from neck still need to connect dark clear green from neck still need to connect brown from neck still need to connect blue from pot still need to connect orange from pot Help @@ElPasoTubeAmps

I have tried both values even up to 10uF to see if it made any difference in frequency response and I see no difference. If it is operating in to a vintage piece of equipment like the Collins, the input Z of the radio is very high so the Xc of the capacitor is always going to be lower for audio frequencies (Xc for a 0.1 uF at 1KHZ is 1600 ohms) but for lower Z inputs like the modern day radios it might be better to use the larger values of capacitor.

The original D-104 element was truly great for the vintage transmitters. It had a higher-pitched sound that penetrated QRM better than most HiFi sounding dynamic microphones. Unfortunately, most original D-104 microphone elements have gone bad over the decades and are no longer available new. The original D-104 is a high impedance device and works best in high-Z input equipment like the vintage transmitters. The electret condenser type microphones of today are much lower Z and work better with modern transmitters. I don't take in work projects anymore but replacing the original element in your D-104 with some of the kits available on the Internet will likely improve the sound from your Yaesu. Hope this helps. 73

Thank you for all the advice. 73!

You must be a lot of fun at parties.