The AN/PRC-74 -- A Covert Contact, An Analog Synthesizer, A Benefit of Channelization, and a Good Thing about Band Noise

I have a sentimental tie to this older military transceiver, for several reasons:

 

-- This was probably the transceiver that we hauled into the Uwharrie national forest when I was in the army in 1983.  I made one 40 meter CW contact with it.  It was interesting for me to see Ray tune the rig up on 40 meter CW. 

-- I like the crude, early, non-digital synthesizer. 

-- This is a good example of the use of an old military rig on 5357 kHz in the 60 meter band.  This is the only one of the chanelized frequencies on that band that is on a whole interger of kHz frequency.  It fit well with the 1 kHz tunability of the transceiver.  Thus we had the "Moose and Squirrel" net on 5357 KHz. 

-- I like how Ray uses the band noise to peak the receiver.  Band noise, you see, has its uses. 

15 kHz of 60 meters FINALLY Liberated! But Watch Out for the 9.15 Watt ERP Limit

My 60 meter rig in 2017

Here's a reminder of how long this took:  When Bob KD4EBM alerted me to the ARRL announcement that 15 kHz of the 60 meter band had been "liberated," I turned to my blog and found articles talking about this possible change way back in 2017.  Oh well, better late than never.  

Here is the ARRL announcement: 

https://www.arrl.org/news/fcc-allocates-60-meter-world-wide-amateur-band-approved-at-wrc-15-continues-amateur-use-of-four-addi

Here are a couple of references from the SolderSmoke blog and one from the BITX Hacks blog in which Don ND6T shifts the BITX40 module's bandpass filter to 60 meters. 

https://soldersmoke.blogspot.com/2017/03/channelized-bitx-60-with-five-channels.html

https://soldersmoke.blogspot.com/2017/03/bitx-sixty-with-three-short-videos.html

https://bitxhacks.blogspot.com/2017/02/cap-stack-hack-putting-bitx40-on-60.html

I reached into my junk box this morning and found the digital VFO I was using way back in 2017.  I may turn to Don again for help in getting the VFO segment to work. 

I got a chuckle about the FCC power limit:  9.15 watts ERP.  Wow, such precision! Can you imagine the FCC breaking down a radio amateurs shack door after, perhaps, measuring 9.16 watts ERP?  BUSTED!

SolderSmoke Podcast #218: S-38E Woes; CW filter for uBITX; A Teensy Explosion; Mint, Cheese and Peaberries; Mailbag; A SPECIAL PLEA FOR FEEDBACK

SolderSmoke Podcast #218 is available 

http://soldersmoke.com/soldersmoke218.mp3

SolderSmoke 218 is Sponsored by AF4K Crystals: 
 Bry Carling can get you the crystals you need. 

Go to:  http://www.af4k.com/crystals.htm

Flying drones with Billy.  Amazing tech out there.  In the 50 buck range with video cameras and facial recognition and tracking.  Check out Air Pix. 

Bill's Bench: 

Active CW filter in uBITX. 

Hi-Per-Mite from 4 State QRP.  Easy to do. Works well. 

uBITX to 5 W level. 

S-38E adventure.  

Replaced antenna input coil BUT -- it came from an earlier S-38 and doesn't resonate. 

So I bought a junker on e-bay and will take the E model coil out of that one. 

Had to re-string the dial!  And add rosin to it from Maria's old violin. 

BFO was not working.  Bad buzz sound. 

So:  Re-cap, Re-tube, Re-string, Re-align, Re-build power supply.  

Shortwave sounds good.  Nice to hear music coming from our machines.  

SHAMELESS COMMERCE DIVISION:   Please use the Amazon Search Box in the upper right hand portion of the blog.

Pete's Bench

A teensy-weensie explosion and fire

Mint!  Kl7FLR

60 Meters

Cheese    Microscopes

Peaberry

Radig

California hams using online SDR receivers for local nets.  

News You Can Use!

J-310s in LTSpice

MAILBAG

K5HCT August via Regen and YouTube

Doug WB5TKI and his wife read "Us and Them."

Rich K7SZ finally following SolderSmoke Podcast.  Welcome aboard Rich. 

Rick KD4KRA  His son was one of the kids in the MIR-Classroom contact that I monitored around 1993...

David AD8Y  Read SolderSmoke Book.  Similar Knack story.  Shared 1978 story:  Homework net on 75 meters.  

Paul KL7FLR Tapping and other tribal knowledge. 

Dave K8WPE   Says I'm fortunate to have a supportive wife.  So true. 

SPECIAL REQUEST:   IT IS VERY DIFFICULT FOR US TO KNOW HOW MANY PEOPLE ARE LISTENING TO THIS.  SO PLEASE, SEND AN E-MAIL TO SOLDERSMOKE@YAHOO.COM   JUST SAY THAT YOU LISTENED TO PODCAST #218 AND TELL US HOW YOU LISTENED TO IT (ITUNES, DOWNLAD FROM BLOG, STITCHER, PODBEAN, WHATEVER...  THANKS

http://www.af4k.com/crystals.htm

SolderSmoke Podcast #207 -- 15 mtrs, 60 mtrs, Giants of Radio, Cubesats, Pete's rigs, SDR MAILBAG

SolderSmoke Podcast #207 is available: 

http://soldersmoke.com/soldersmoke207.mp3

-- Giants of Radio
-- Pete on 15 Meters
-- Bill on 60 Meters with the uBITX
-- Pete's Sudden and Heath Filter Transceivers
-- Cubesats to orbit!  To the moon!  And to Mars! 
-- Bill rebuilds his 2 meter "Ray-Gun" Quad (for Farhan's Cubesat)
-- Homebrewing Variable caps and stockpiling NP0
-- My "by ear" Minimal Discernible Signal Technique
-- Thoughts on Direct Sampling SDR and the Radio Art
MAILBAG
-- A request for feedback from GQRP
-- G4WIF reports G3ROO on UK TV with spysets
-- VU3XVR builds FB rig from EMRFD
-- M0KOV Charter member of the 3 Scratch-built BITX club
--KD4PBJ's PTO Turtle DC Receiver
-- AB1OP builds Pete's LBS receiver and gives us a new acronym: SITB
-- KD4EBM -- Thanks for the scanner Bob!   
-- A possible sponsor from California... 

-- Pete's dream neighborhood...

uBITXs Doing Very Well on 60 Meters -- with Boris and Natasha

Last Saturday something told me to get on 60 meters.  TRGHS.  So I stepped out to the carport and tuned the doublet to 5.3 Mhz -- and I'm really glad I did.  There was a lot of activity on the band, all very friendly.  Channels 1 and 2 seem to be especially popular watering holes.  

Channel 3 might be getting a bit more digital use, but a very interesting group called the "Moose and Squirrel Net" meets there at noon (east coast time) on Saturday on SSB phone.  This group is kind of a spill-over from the Old Military Radio Net that meets early on Saturday morning on 3895 kHz  AM.  Because many of the old military radios can't tune on half kHz increments, the "Moose and Squirrel" group used channel 3 which is the only U.S. 60 meter channel on a whole integer kHz frequency (5357.0 kHz).  Moose and Squirrel takes it name from the old Boris and Natasha Cold War cartoons that many of us watched as kids.  Natasha Fatale and Boris Badinov.  Cold War era military radios, get it?  Good stuff.  Many of the guys on the M&S net commented on how nice the uBITX sounded.   I was running it through my .1kW CCI EB63A amplifier. 

One of my nicest contacts was with Joe WA2EJT.  He told me that he too has a uBITX.  He said he bought the rig in part because of he liked the fact that Farhan was giving the work on the toroids to some ladies in Hyderabad who normally do sewing.   Joe said he liked the look of the uBITX board so much that he decided to put his  board on top of the chassis instead of inside it.  That is exactly what I had done with  my first BITX 40 module.   See the pictures of Joe's rig. 

Three cheers for the uBITX! 

Boris, Natasha and "Fearless Leader" 

SolderSmoke Podcast #195: (We need some help!) BITX, 60, SSB History, Tribal Socketry

SENDING IT BACK

SolderSmoke Podcast #195 is available.  Link appears below (scroll down)

We’ve got a problem:   Pete Juliano and the QRP Hall of Fame  :-(  PLEASE HELP!

BENCH REPORTS

Pete Releases Smoke (wiring harness)

Pete's DifX on 60

Architecture and Dual Conversion (uBITX:   uses ALL THREE clocks on the Si5351)

The Big Kahuna

ON HACKADAY with Philco SB100 SEE!  QRP!!!!!

BITX60

Cap Stack Hack mod (with leads)

Let the smoke out of an Si5351 (shorted output) Several actually.

(Same day delivery zone for Amazon -- but no drones or parachutes yet.)

Installed scanning switch

Observations on 60.  All the weird bands have a 6 in them: 160, 60, 6

The good:  100 watt limit, wire antennas 
The bad:  Kind of cliquish-- like 75, not much of a CQ band.  Channels.  Not much activity.

Met Josh KE8CPD on 40.  BITX 40!

TRIBAL KNOWLEDGE:

Socketry:  How to keep BNC jacks from spinning loose?

Do you heat shrink?

Feel Tech Sig Gen might not have blocking cap at the output.

Speaking of which, when I spoke of the Ne602, I mostly meant blocking caps, not bypass caps.

How come they don't have a cable TV channel devoted to radios?  They have HGTV? Why not HBTV?

REPORT FROM WINTERFEST

Bad weather.  Tailgaters wimped out!

Combined forces with Armand WA1UQO.

Met up with Charles AI4OT.

Acquisitions:  1/4 phono jacks, carbon mic, vero board, disc caps, weather radio,

LARGE collection of Electric Radios from Armand.  Wow.

Electric Radio notes:   1st Fifty Years of Sideband 1991 articles by Jim Musgrove K5BZH

Why LSB on 75? -- so AMers couldn't follow to top of band

W2, W6, W8s liked phasing, W3, W4, W0 more into filter rigs.

Early SSB guys turning on carrier and talking AM hams into SSB RX.

Kelvinator Refrigerator rigs.

A reading on the homebrewing of SSB rigs.

Tony Fishpool on QSO Today!  Pete mentioned prominently.

Good Hacks from ND6T on BITXHacks,   Stockton Bridge

MAILBAG

LINK:  http://soldersmoke.com/soldersmoke195.mp3

Pete's 60 Meter DifX

Oh man, run -- don't walk -- to the N6QW blog and check out Pete's amazing 60 meter DIFX transceiver.  DifX is another N6QW contribution to the lexicon: it refers to a transceiver that has an architecture DifFERENT from that of our beloved BITXs.  Pete means no disrespect to the BITX -- he just sees the value in sometimes doing something different.  I understand this completely -- I myself am on my FIFTH BITX   (three scratch-built and two modules) and definitely felt the need to do something different. (That's why I built the OLED NE602 rig.)  

Once again Pete Juliano shows himself to be a man ahead of his time: Anticipating FCC approval of a VFO tune-able segment in the band, Pete has made Channel 3 on his rig tunable with a rotary encoder.  Hopefully, we will all soon need this.  Pete is already there. FB OM.

My reaction to 60 meters has been very similar to Pete's.  We will talk about this on the next podcast (this Saturday).  

Pete's blog has a great description of the new rig, complete with a really nice video.  Check it out:

http://n6qw.blogspot.com/2017/03/a-new-line-of-transceivers-difx_23.html

Channelized! BITX 60 with the Five Channels (with video)

Here's an update on my BITX 60 project.  The modified module is in the lower box.  An Arduino Uno and an Si5351 (this one with unreleased smoke) is in the Heath QF-1 box on the top.  I am using an Arduino sketch written by Don ND6T. It spits out the needed 17 MHz LO freq needed for each of the five 60 meter channels. You can scroll through the channels by just holding down the rotary switch interrupt button.

There is a move afoot to liberate from channelization about 15 kHz of the 60 meter band. When that happens, I'm ready to go -- I'll just reconnect the rotary encoder for the Si5351 and load some new code.  I suspect that by the time that happens, Don will have modified his code so that the 15kHz "tunable" segment will be integrated into the current program and will appear as one of the options as you scroll through the choices. 

For reasons that most readers will understand, I have resisted channelization for many years.  But here I am, channelized on 60.  It is not so bad.  I'm having fun listening to a new band, using a modified BITX, an Arduino, a bit of Heathkit and code from a fellow ham.   

BITX 60 (with three short videos)

Inspired by Don ND6T, I decided to put a BITX40 Module on the 60 Meter band.  All you really have to do is modify the bandpass filter.  Don showed us how to do this by simply adding three 100pf caps.  I was going to order SMD caps, but this just didn't seem right -- I found three of the old "with wires" kind and easily soldered them into position.  The bandpass shifted as Don had promised.

You also have to change the VFO freq.  You need it to be in the 17.3 MHz range. Don has a nifty program for the Raduino that also works with the Si5351/Ardunio Uno combo that I use.  It keeps you on the five channels currently authorized on 60. Unfortunately I managed to let the smoke out of yet another innocent Si5351 breakout board.  Amazon and Lady Ada are sending me another one, but in the meantime I pressed into service an old AD9850 DDS. I had a little trouble getting the 17MHz signal through the BITX's VFO 4 MHz VFO system, but I eventually figured it out. (More on this later.)  

The receiver is working nicely.  I like the relaxed 60 meter conversations. 

Walking the Plank with N8NM's 60 Meter Rig

Steve N8NM writes:

The free-range rig is coming along!  I'm receiving with decent sensitivity (my generator's only calibrated to -100 dB/m, and I hear a CW note there just fine) and I'm getting about -2 dB/m out of the mixer.  Yippee!

I ended up using an IF of 20 MHz, mainly because I had a bunch of crystals left over from my Minima.  The architecture (left to right) is: Diode ring mixer using 1N4148s, 20dB W7ZOI bilateral TIA, 6 pole crystal filter (BW ~= 2.3 KHz), Another 20dB bilateral TIA, 1N4148 product detector (cribbed from the Minima), 2N3904 audio driver, LM380 PA.  Microphone amp is two FET stages (J310).  Oscillators are courtesy of an Si5351, controlled by an Arduino Uno.  T/R switching is done using a couple of counterfeit 2SC1969 RF transistors that, ironically, don't amplify at RF, but work fine as power supply "pass" transistors.

Yet to do is the PA, which I've noodled in LTSPICE (shooting for 20W PEP using a bunch of BD139s, just because...) and cleaning up my Arduino sketch.  Right now, I just modified the start-up values of the sketch from my all-band rig for testing.  Since that code is pretty full featured (dual VFOs, RIT, filter switching, LCD Display, etc.) using multi-function pushbuttons to select all sorts of crap, I'm betting that 80% won't be used in this rig.  Adding simplicity is always good.

So, nearing the end, I'm already thinking about my next rig (that and building a 60m antenna...)  I think this one will be similar to my "all band" rig, but limited to the WARC bands (I have a WARC tribander that's screaming for a rig of it's own.)  That's kind of boring, so, to challenge myself, I'm going to try using a touch screen in lieu of the usual pushbuttons.  What would really be cool, though, is an interactive slide-rule dial - don't think anyone's done that before!  One of the things that has always drawn me to the SX-101 is that large slide-rule dial.  To me, that allows each station to occupy a physical place on the dial, so after scanning the band, you know were everyone is.  It's really a joy to operate those rigs!

73!  Hope to work you HB2HB on 60M soon!

-Steve