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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?

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.

Saturday, July 8, 2017

Stop Me Before I Commit an Electronic Atrocity!

Sadly, not mine
I like the D-104 mic.  I bought one from Astatic shortly before they went under and it has provided good service with many different rigs for a long time.

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? 

Steve N8NM Gets Modular -- With Both Hardware and Software


Steve N8NM has an excellent article on his blog about the benefits of modularity.  He breaks new ground by extending the concept into the software realm.  Check it out:

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.

Thursday, July 6, 2017

Another LM373 Rig - Pete Is Not Alone!


Tuesday, July 4, 2017

The Radio Laboratory at Bandung, Java -- SSB in 1927


Anton PA0AST alerted me to this important piece of radio history:

The first phone radio between Indonesia , the city of Bandung ( Dayeuh Kolot, Jalan Radio 1 ),  and Holland , Radio Kootwijk  were made  in SSB already in 1927... Before that time they had only a CW  1 Mega Watt spark transmitter in Malabar.
One of the receivers still exists in a museum in Amsterdam (cdvandt ). It is 3 meters in length and 2 meter in  height....  All made with plug-able units with 1 tube inside .


The transmitter was 10 kW. Ua was 6kV was made by dynamotors. Transmitting Tubes locally made by craftsman in a workshop.  Both  buildings as well  in Bandung and in Kootwijk still exists .


Anton

The old images come from:
http://www.cdvandt.org/bandung-lab-kwk.htm


At the other end was Radio Kootwijk in Holland. 

Before you jump to the English version of the page, be sure to check out the Drone video of the site, and the audio file of the Morse transmissions: 

http://radiokootwijk.nu/     Thanks to PA0JWU for the wonderful site.

Quite an impressive shack!  My favorite part is the note indicating that local residents cleaned out the cooling pool and used it for swimming each summer.

Sunday, July 2, 2017

AC9JQ's Mini Digi VFO/BFO Al Fresco with OLED (and noise test)



From Dean AC9JQ:

Just completed the VFO/BFO/Arduino/OLED module for my radio.  I also have the LPF, BPF and crystal filters completed and tested.  Next will be the audio amplifier and NE602 modules.  I will probably build one of the NE602 modules and test things out as a DC receiver.  My ultimate plan is to have the rig no more that 1"x3.5"x3".  I still have a lot of "stuff" to stuff into that size of box.  I'll keep you posted.


I have been able to contain the entire Arduino/Si5351/OLED into a small cube in the front.  The rest of the radio has to fit on two levels in the rest of the area behind the Arduino/Si5351/OLED.  I think I will build the audio section and on NE602 mixer and run it as a direct conversion first to vet out any noise or other problems.  Bill, that small coax that you pointed out will really help on this build.  I used a small piece as a power feed-thru and will use it to feed out the VFO/BFO signals, thanks again for that pointer.

I decided to test for noise on the TIA transceiver test bed.  See the video of the results.  Not too much noise.  I'm only using my indoor magnetic loop for an antenna.  Video is kind of sloppy, but taking off the antenna and turning up the volume shows how little noise is left in the system.  Now time to stuff the rest of the radio into the tight quarters.

I purchased OLED from ebay.......

They are nice and compact, although as time goes on, I'm sure they will be harder to read.  I'm hoping to have an alfresco version in a week or two.  I used much of Pete's code from the shirt pocket transceiver upgrade, modified the code to address the smaller display and add USB/LSB capabilities. 

73's  Dean AC9JQ
Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column