D-104, only slightly OT
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Good morning,
I have an old D-104 that worked fine when last used (1977) and want to use it with the K2. I know I could replace the element with one from Heil, but I would prefer to keep it as original as possible (it does have the preamp in the G stand base). I will assume the preamp works, and I know the K2 works, but I'm not so sure about the original element in the mic. Does anyone know a way to test the element before wiring it up? Thanks es 73, Tom, NG3V _______________________________________________ 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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The D-104 is an excellent microphone for the K2 (and K3), Tom. Because
the ceramic/crystal element is high impedance, your best way of testing it is to wire it up and try it. The pre-set gain control will need to turned fairly well down. Connect it to the 8-way plug: WHITE (or CLEAR) to pin 1 (audio) RED to pin 2 (press to talk) SCREEN to pin 7 (ground) 73 David G4DMP In a recent message, NG3V <[hidden email]> writes >I have an old D-104 that worked fine when last used (1977) and want to use >it with the K2. > >I know I could replace the element with one from Heil, but I would prefer to >keep it as original as possible (it does have the preamp in the G stand >base). > >I will assume the preamp works, and I know the K2 works, but I'm not so sure >about the original element in the mic. > >Does anyone know a way to test the element before wiring it up? David G4DMP Leeds, England, UK _______________________________________________ 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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In reply to this post by ng3v
> I know I could replace the element with one from Heil, but I would prefer
> to > keep it as original as possible (it does have the preamp in the G stand > base). Tom, Odds are the crystal element is still in good shape, provided it has not been subjected to a high humidity environment over an extended period of time. Also, anyone contemplating the use of the D-104 with the stock Astatic amp should consider an alternative buffer amp. The input Z to Astatic's 2-stage preamp calculates to 470K-ohm -- way too low for a crystal cartridge. The crystal cartridge should see a termination of no less than 5 megohm, and preferably greater than 10 megohm in order to preserve reasonable low-end response. The series capacitance from a typical crystal cartridge is anywhere from 800pF to 1600 pF. Calculate the - 3dB turnover point into various terminating resistive values and you'll see why it's important to completely unload the crystal cartridge. For simplicity and excellent performance, I favor a single transistor JFET, configured as a near unity-gain source-follower. The web is full of FET and op-amp designs for the D-104, but nearly all of them suffer from inadequate design, particularly with respect to crystal cartridge loading. Most designs I've seen attempt to bias the FET as the analog of a "grid leak" resistor used on a vacuum tube grid. As a source follower, the FET is completely self-biased when the correct source resistor value is used. The D-104 crystal cartridge can be attached right to the FET's gate with no other components necessary. For isolation, I add a 5-meg resistor in series with the gate, but this is not strictly necessary. If gate failure is a concern from static electricity, some ops have used a 10-megohm resistor from the gate to ground in an attempt to bleed static build-up.. I've never found this to be necessary. If all of the above sounds like too much work, simply insert a 10-megohm resistor between the D-104 cartridge and Astatic's 2-stage preamp. Signal to noise and distortion performance will suffer, but at least the cartridge will be unloaded. The Astatic preamp can more than compensate for the loss in level owing to the use of the series resistor. When the K3 is configured for ESSB transmit, the D-104 will sound nearly as good as an expensive studio condenser or dynamic mic. As a final footnote, I recommend ESSB only for use on uncrowded bands, and when signal strength is high. Otherwise, it's a waste of occupied bandwidth. Paul, W9AC _______________________________________________ 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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In reply to this post by ng3v
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In reply to this post by P.B. Christensen
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In reply to this post by AC7AC
> "The Astatic D-104 was designed as a *communications* microphone with a
carefully shaped frequency response for speech and not for extreme high or low frequency response." Although the presence rise was a design attribute of the mic, limited low-end response was not. The D-104 was produced in the early 1930s as a communications microphone intended for reasonably good, balanced audio response in the AM mode -- not SSB. SSB as used in radio communications is a post D-104 phenomenon. Use of the D-104 pre-dates common SSB use in the amateur service by 20 years. According to Astatic, their 2-stage buffer amp was designed as an active impedance transformer as low-Z solid-state devices were being ushered-in during the 60s Astatic never intended for the preamp to be used as a "power mic" device. It was the Citizen's Band operators who made the added gain function popular. That said, Astatic could have designed a much better buffer for the D-104. > "The graph of the audio response published by Astatic, using the built in amplifier, shows 0 dB at 1 kHz. Below 1 kHz the output drops off smoothly to -5 dB at about 200 Hz, then more steeply down to -10 dB at 100 Hz where the published curve ends." The typical D-104 with 2-stage preamp is substantially more response limited than that shown in Astatic's graph. The response plot shown in their instruction sheet is hardly a scientific measurement and the response can vary considerably across cartridges. > "That roll-off is important since excessive low frequency response robs a signal of intelligibility and "punch" since the bulk of the energy, but virtually none of the modulation in the spoken voice is down in those ranges." True of weak signal communications. Not true when the SNR is high - and the reason for the disclaimer at the end of my post. If your theory is correct, I doubt Elecraft would have included ESSB as a design feature into the K3, The lowest fundamental of the deepest male voice can be measured as low as 70 Hz -- and is typically 75-85 Hz. It's not that spoken voice does not produce frequencies that low, it's that historically, SSB transmissions have been deliberately bandwidth-limited. > "That rising characteristic to a peak in the roughly middle point of the speech audio spectrum is what made it so effective in communications and made it so popular." The D-104 became popular for a variety of reasons including cost, aesthetics, availability in the golden age of AM, reasonably good and balanced frequency response, etc. Paul, W9AC _______________________________________________ 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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In reply to this post by P.B. Christensen
Not much of a RTTY person, but have had several requests for
RTTY qsos for the Triple Play LOTW award going on, so today I had a request, got the manual out and in a few minutes had RTTY perking along just fine. Quite a relief after having to have interfaces and computer hooked up etc. Worked quite well. Thanks Elecraft. I seem to remember some thead about the length of the diddle after the qso is over, is there a way to shorten that up. dont need all that time in transmit between qsos. Something I did not see in the manual? Thanks 73 Merv KH7C K3 2306 _______________________________________________ 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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In reply to this post by P.B. Christensen
I've been using the setup you describe with a K-2 for about 10 years
without problems. In fact I've gotten a few unsolicited compliments on audio over the years. Mine is wired just like David Pratt described. I have the K-2 set for SSBA-1 (attenuator in) and the mic gain pot about half way up. I just turn up the pot until 1 ALC led blinks a bit on voice peaks. To test, hook it up and ask a friend how it sounds! 73, Lenny W2BVH _______________________________________________ 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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To all who took the time to reply - Thank You.
I've been wanting to do this since I finished the K2 but have never gotten around to it. I bought the Heil desk mic and classic stand with the K2 and I guess I'll have to sell it now to force my own hand. 73, Tom -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of w2bvh Sent: Tuesday, January 20, 2009 4:52 PM To: [hidden email] Subject: Re: [Elecraft] D-104, only slightly OT I've been using the setup you describe with a K-2 for about 10 years without problems. In fact I've gotten a few unsolicited compliments on audio over the years. Mine is wired just like David Pratt described. I have the K-2 set for SSBA-1 (attenuator in) and the mic gain pot about half way up. I just turn up the pot until 1 ALC led blinks a bit on voice peaks. To test, hook it up and ask a friend how it sounds! 73, Lenny W2BVH _______________________________________________ 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 _______________________________________________ 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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In reply to this post by Merv Schweigert
Sending "..--" truncates the usual 4-second idle time to 1 second or
so. I think of it as an "IM" prosign, for "IMmediately stop sending." Have fun! 73, Wayne N6KR On Jan 20, 2009, at 11:46 AM, Merv Schweigert wrote: > > I seem to remember some thead about the length of the diddle after > the qso is over, is there a way to shorten that up. dont need all > that > time in transmit between qsos. Something I did not see in the > manual? > --- http://www.elecraft.com _______________________________________________ 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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