I've been experimenting with electret replacements for the D-104 crystal element. I found this site with a really excellent description of what lies inside those little electret capsules. Here it is:
http://www.openmusiclabs.com/learning/sensors/electret-microphones/index.html
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Sunday, July 16, 2017
Saturday, July 15, 2017
Dino's FB W1FB Crystal Tester
A couple of weeks ago I noted that the complexity of DeMaw's circuit caused many of us to wimp out on this test gear project. I joked that those who had built the device might be able to set up small businesses to do the testing for the rest of us. Perhaps our friend Dino can cut a deal with G7WKE to divide up the world market for crystal testing: Dino could have the Western Hemisphere while Rob covers Europe and points East.
Bill -
Enjoyed seeing someone else who has built Doug’s crystal tester on the blog. Here’s mine, built this back in early 2007. Anyone who wants to duplicate the tester can find the article in the January 1990 issue of QST or the updated article in the W1FB Design Notebook (page 192). Note that the QST article has a missing component value and a missing component (both corrected in the Design Notebook):
Bill -
Enjoyed seeing someone else who has built Doug’s crystal tester on the blog. Here’s mine, built this back in early 2007. Anyone who wants to duplicate the tester can find the article in the January 1990 issue of QST or the updated article in the W1FB Design Notebook (page 192). Note that the QST article has a missing component value and a missing component (both corrected in the Design Notebook):
(1) R24 is missing its value - it’s marked in the Notebook as 56 ohms.
(2) There should be a 220 ohm resistor connected between the output pin of U2 the LM317T regulator and the top of R1 the voltage adjust pot that is connected between U2’s adjust pin and ground [corrected in the March 1990 QST Feedback column].
I built a FT-243 adapter to let me work with larger crystals.
73 - Dino KL0S
Labels:
DeMaw--Doug,
Filters,
test gear
Friday, July 14, 2017
And Now For Something Completely Different: 70cm FM
So there I was, talking to KE5FV on my scratch-built 17 meter BITX, when in walks my son Billy with this walkie talkie. "Hey Dad, I'm cleaning out my room -- could you use this?" I'd seen it before but I thought it was some Family Radio Service device that he had picked up. But no! It is one of those very cheap Baofeng UV-5R FM transceivers. I soon found myself scrolling through menus, trying to figure out how to use the strange new appliance.
I got it on 70cm and soon established contact with a Bill W3HXF -- that was my first ever UHF contact. We then switched to 2 meter simplex.
It works fine. I've been looking for something different. This could be fun. Any suggestions on how to make the most use of this thing?
I got it on 70cm and soon established contact with a Bill W3HXF -- that was my first ever UHF contact. We then switched to 2 meter simplex.
It works fine. I've been looking for something different. This could be fun. Any suggestions on how to make the most use of this thing?
Sunday, July 9, 2017
Have You Ever Seen What's Inside a D-104 Crystal Element?
I had not seen this I must say, I am disappointed. I had visions a circular collection of shiny Rochelle salt crystals. But look at this thing. It is quite flimsy -- not at all what you'd expect from the sturdy D-104 exterior. It has kind of a "Wizard of Oz" behind-the-curtain feel to it. Yuck. If I can't find a D-104 element in good shape, I might reach for a dynamic element or -- gasp -- an electret.
Labels:
Microphone
Saturday, July 8, 2017
Stop Me Before I Commit an Electronic Atrocity!
Sadly, not mine |
I wanted another one, primarily for my DX-100/HQ-100 station. I saw one on e-bay and a few days later it was here. Unfortunately the seller was correct when they warned that it showed no output. I had hoped it was a problem with the amp in the base, but no, it seems that the crystal element is quite dead. It is an MC320 cartridge marked 7-77. There is an aluminum sheet at the front that is apparently supposed to be riding atop a center support that connects mechanically with the magic crystals. But it looks like a circular tent that has poked through the center support and collapsed around it.
Just a few years ago there were some options for replacement elements, but it seems that most of these are gone. Bob Heil does have a dynamic element replacement kit for about 68 bucks.
There are many schemes for putting electret elements in the old D-104 head... I was reaching for the junk box but I stopped myself. NO! I will try not to commit this kind of electronic barbarity. (I have already sinned by killing several QF-1 Q multipliers and a couple of Benton Harbor lunch boxes.) I will instead turn to the SolderSmoke brother/sisterhood and ask if anyone out there has a crystal element that could bring this old mic back to life. My DX-100 deserves nothing less.
Anyone have a D-104 crystal element in their junk box?
Labels:
Heil -- Bob,
Microphone
Steve N8NM Gets Modular -- With Both Hardware and Software
https://n8nmsteve.blogspot.com/2017/07/sr-16-lets-get-modular.html
Subscribe to Steve's blog, or link to it. Hopefully this will encourage him to post more great things like this.
Labels:
software
Thursday, July 6, 2017
Another LM373 Rig - Pete Is Not Alone!
Bill,
Thanks for coming back to my call. It was a thrill to finally catch you on the air.Like I said my Soldersmoke marathon was amusing and kept me in great company on my round trip drive from Murphy NC to Chicago. While I was in Chicago I emptied my storage garage of goodies that have been there for 12 years, it was like Christmas in June. I uncovered treasures I didn't know I even had and yes I found the box of project boards that kind of or didn't work at all. I now have these treasures to play with and see with renewed eyes what I may have done wrong, or burned up. It looks like a few of these modules can be made into rigs.
I also found a couple of antennas that I traded for that never made it up.
Also the bigger surprise was how many parts I had kept especially the ICs that were intended to beused in rigs like the LM373's that Pete has talked about. I have one test circuit board to test the LM373 that just needed the oscillators so with my SI5351 breadboards I have what I need to get this going.
Now that I'm settled into my new QTH in the wilds of western NC I will noodling and tinkering moreto get my little DSB rig on the air and an LM373 based SSB rig too, using mostly or all obsolete/vintage parts. This is something I have been noodling about for sometime now.
I also will get my MMM finished.
Thanks again for the QSO and I look forward to working you again. Now to melt some solder.
73,
Skip Davis. NC9O
---------------------------
Pete's LM373 page: http://www.n6qw.com/LM373.html
Labels:
DSB,
LM373,
Michigan Mighty Mite,
Si5351,
SSB
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