A Great Morning on the Old Military Radio Net: AB9MQ's Central Electronics 20A, W3EMD's Dynamotor, WU2D

Just a portion of Masa's shack

I usually try to listen in on the Old Military Radio Net on Saturday mornings (3885 kc).  Lately I listen with my Mate for the Mighty Midget receiver.  

This morning's session was especially good.  For me the highlight was when Masa AB9MQ called in from Normal, Illinois using his Central Electronics 20A (see below).   That was one of the earliest SSB rigs.  A phasing rig, it also ran AM (which was what Masa was using this morning).  He had it paired up with a Central Electronics 458 VFO.  You folks really need to check out Masa's QRZ.com page: 

https://www.qrz.com/db/AB9MQ

Buzz W3EMD called in from Rhinebeck, NY.  I could hear his dynamotor in the background.  Buzz said hello to Masa in Japanese.   FB.

Always great to hear Mike WU2D. 

Solder Smoke Podcast #147 -- Hurricane Sandy Edition

Hurricane Sandy backup station at N2CQR

SolderSmoke Podcast 147 is available for downloading: 
http://soldersmoke.com/soldersmoke147.mp3
October 29/30 2012
Hurricane Sandy on the way
Thanks for birthday wishes 
Einstein -- a very nice fellow with a bit of the Knack
Rocket project update
808 key chain cameras (thanks for the Amazon support!) 
Audio output transformer for Barbados Barebones RX
Mighty Midget RX -- breaking it, fixing it (with help from friends)
Freq counter connection to Tek scope  
Halli S-38E -- How to avoid electrocution?
The HQ-100's anti-drift alarm clock 
Book Review:  "Instruments of Amplification" by H.P. Friedrichs (5 Soldering Irons!) 
BANDSWEEP: 20 meter SSB via DC receiver on hurricane day
Report on outcome of the hurricane -- inverter saves the day (really the night)
MAILBAG (a big one).    

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Radio New Zealand Booming in on 7245 AM

The day is off to a good start here at SolderSmoke HQ, with Radio New Zealand booming in on my homebrew Mate for the Mighty Midget receiver.  I was listening from around 0900 to 1030 UTC on 7245 kHz. Once again we see that The Radio Gods favor homebrew receivers. Gray line propagation also played a role.  

Above we see a technician at work at RNZ in 1945.  More historic photos here:
http://www.pcc.govt.nz/About-Porirua/Porirua-s-heritage/Porirua-s-suburbs/Titahi-Bay/Historic-site--Radio-New-Zealand-Transmission-Station

W1UX

Now THAT'S a ham shack! My Mighty Midget receiver allowed me to listen in this morning to Al, W1UX, and friends on 75 meter SSB. One of Al's AM operating positions appears above.  Note the DX-100.  And the R-390 (want one).  And the Tek 465. I've been a big fan for years.  Check out Al's boatanchor web site:    http://www.tinyradio.com/boatanchor01.html  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

SolderSmoke Podcast #149

Podcast #149 is now available:  http://soldersmoke.com/soldersmoke149.mp3

17 February 2012

IGY intro
Cappuccio turns off TV on New Year's Eve
Pre-inaugural day on the National Mall
The importance of audio bandwidth in DSB rigs
On 15 meters with the HT-37 and the Drake 2B
Q Killing and Swamping
Adding a Filter the Mighty Midget Receiver
Italian lessons via Echolink
Billy and the Raspberry Pi -- Three Cheers for Ada Fruit
Translate Button on the Blog page (upper right)
C.F Rockey SK
Mailbag: Kludge or Klooge?  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Short Video of Mate for Mighty Midget

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

SolderSmoke Podcast #188: Blue Rig, 6U8 RX, Dial strings, Hamfest, VFO Builds, MAILBAG

SolderSmoke Podcast #188 is available.

http://soldersmoke.com/soldersmoke188.mp3

Audio "sparkle"

Bench Reports:
Pete: Blue Rig, Amplifier Project, LBS and Simpleceivers around the world
Si5351s in the new Elecraft KX2

Bill: 
Mighty Midget Mate 6U8 RX Refinement
Using a Millen 61455 IF can
Broad, but beautiful. But not as nice as PA3GSV's
Tweaking a VFO the old fashioned way
Reduction Drive Re-works.
A Confession:  Using Amplified Computer Speakers

Back to the lipsticked pig.  Pete convinces Bill to fix the S38-E
dial cord. 

Manassas Hamfest Report.

Field Day.

Mysteries:

Who is WV2YAU

Who sold Bill the hombrew SWR meter at Manassas?

MAILBAG

Inside a Millen 61455 IF Transformer

I found this in my junk box.   I've put it in my old Mate for the Mighty Midget receiver, in the place of the Toyo  CM455 crystal-mechanical filter (which I found to have excessive insertion loss).  I think its very cool how they squeezed two variable caps into that little can.  Designed in 1956.  Works great.  Note the promised passband: 4.7 kc at 6 db down.  Not bad for an LC device.
Here is the spec sheet:

 

Eddy's "Salvage Super"

I had our friend Grayson (in Turkey) in mind when I put Eddy's messages about this "thermitron" receiver on the blog.  

Here's my version of the famed "Mate for the Mighty Midget": http://www.gadgeteer.us/erart.htm 

Hi Bill,

Many thanks for the FB note...

Well, I think my buddy VE3CSK is 99% "hooked" on the notion of making an MFTMM receiver for himself---and that's a good thing. That rascal of a rig is pretty much fool-proof, & the design sure does lend itself to no end of enhancements / improvements / changes / mods! I should know: with my set-up here I added AVC, and extra IF stage, an extra stage of AF, more pre-selection, etc. etc. etc.

As for selectivity, I simply incorporated regeneration in the 2nd IF stage: with judicious tweaking of the BFO, one can achieve a near single-signal selectivity effect that is GLORIOUS on CW. I guess one can make these things as complicated---or as simple!---as we might chose to do, yet further proof of the flexibility of this receiver.

I've taken some jpegs of my set-up here, and am attaching them herewith for your perusal. I like the notion of using these rigs on 80- and 40-meter AM, too---but am presently somewhat "distracted" with the task of re-inking my main tuning dial for my 1929-style superhet.

I think my next step in my MFTMM receiver here will be the addition of an internal 125 VDC power supply---most likely will mount the components inside, on one of the vertical sides (still LOTSA room there!). I have a FB Hammond power transformer that'd be perfect for the job, & I won't have to connect / dis-connect / re-connect its current out board power supply (that I use with other peripherals, too---a REAL pain by times).

~73~ de Eddy VE3CUI - VE3XZ

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

SolderSmoke Podcast #234: PSSST, KWM-1, VHF Woes, Mighty Midget, TinySA, 17-12 Dual-Bander Advice Needed. MAILBAG

http://www.gadgeteer.us/17SSB.HTM

SolderSmoke Podcast #234 is available: 

http://soldersmoke.com/soldersmoke234.mp3

Roots of SolderSmoke: The "Click and Clack" of ham radio? 

Influences: Jean Shepherd, CarTalk, Shortwave stations.

Steve "Snort Rosin" Smith WB6TNL?  No. Steve "Aching Sinus" Smith WA6SOC  

Pete's Bench:
PSSST Super Simple SSB -- 7 Transistors. Switching IF Module: 

PSST Details:  https://www.n6qw.com/PSSST_20.html
DC RX.
KWM-1 Resurrection "Shame Shelf".
How to make things work:

http://n6qw.blogspot.com/2021/10/how-to-make-things-work-tribal.html
Diode Switching or Relays?

(Why the T/R diodes in the BITX 20 amplifiers?)
National Receiver.

Bill's Bench
Farhan's Talk to RSGB got me thinking of VHF 2 meter AM.
2 meter Benton Harbor lunchbox madness. SuperRegens Super Strange.
I broke my Maplin AF Sig Gen in the process. Fixed it.
Playing with MMMRX again. Put in 6 kHz ceramic filter. Sounds great SSB and AM.
Swept IF with noise, TinySA, and NanoVNA. Need better noise gen.
Mod to listen with TinySA (on blog).
Thinking of 17 meter /12 meter Dual-Bander IF around 21.4, VFO around 3.41 Mhz. Thoughts?
Sweeping double half lattice filter from Swan 240.  UGLY.  

MAILBAG:
--- ROOTS OF MAILBAG: Radio Moscow, Havana Cuba, HCJB, others.
-- Thomas K4SWL of the SWL Post: Could have been worse! Stairbag?

-- MY NOVICE LOG -- Heard back from ex-WN2RTH ex-WN2FLK ex-WB2RKK.
-- Drew N7DA worked Wes W7ZOI in Sweepstakes. FB.
-- Peter VK2EMU The movie Frequency and the Magic of Heathkits. Good, but not that good!
-- Thomas KK6AHT! Our old friend. Minima! Now has a young son! FB
-- Chuck WA7ZZE Saw QST profile. Sympathizes with Two-er trouble.
-- Tim M0CZP. Spell corrector. Vatican Diodes. Infallible!
-- Ramakrishnan VU3RDD Working on a NORCAL and a noise cancellation arrangement.
-- Skip NC9O said I was 40 Hz off on 17. But he had a reason to KNOW!
-- Steve K9NVD Glad he's a listener.  
-- Bob KY3R Novice Nostalgia. Should he use 75 watt bulb for dummy load? Yes! 
-- Todd K7TFC Video about why solder smoke goes into the face.
-- Anthony VU3JVX  Homebrew Antuino. I ask for help in moving freq to 450 kHz.
-- Jack NG2E Building Pete's DC RX.
-- Scott WA9WFA HBR-13 and MMMRX.
-- Stephen 2E0FXZ also got a FT-101 VFO.
-- Bob K7ZB on the air with 56 mW and a big antenna.
-- Dean AC9JQ Retired.
-- Allan WA9IRS Right to Repair update.
-- Farhan Invited us to Lamakaan ARC, Dec 11 or 12. Will be on QO100 Satellite Live! 

-- Many suggestions about my Apollo 11 Time Capsule. Still looking for ideas.

Happy Thanksgiving to all who celebrate this holiday!

https://shortwavearchive.com/archive/lsn2565kv5vg2l7s5qanx1mbnwvce5#commenting

A Filter for The Mighty Midget's Mate

The story of my 80/40 meter three tube (all 6U8) superhet receiver is recounted here:  http://www.gadgeteer.us/erart.htm

I've been playing with this RX on and off for many years now.  Somewhere along the line I picked up a 455 kHz filter for it (I couldn't find the 455 kc crystals that Lew McCoy used).  Yesterday I finally got around to putting the filter into the receiver.

There is almost no info on this filter on the internet.  Here are the details"
Toyo Communications Equipment Company Ltd.  CM FILTER
Type: 455 -- 2.4 -- C     Date:  8- 69

On the bottom, there are four terminals.  They are marked "P" "B" "E" and "G".   Does anyone know what these letters signify?  

 I experimented and it seemed like putting a 455 kc signal into P and B, and taking the output from E was the way to go.   I've left G floating. It works, and the improved selectivity is very evident.   But I'm operating with no specs on the filter, so I may have it in there upside down and backwards. And of course, I am operating with my usual disregard for impedance matching issues.

Here's how I've placed it in the circuit: 

Ideas, suggestions and even admonitions would be appreciated.

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Putting a Ceramic Filter in the "Mate for the Mighty Midget" Receiver

It is really simple.  I had one of the +/- 3kHz (6 kHz wide) 455HT filters on hand.  The spec sheets call for 2000 ohms at both ends, but looking at the schematic it appeared that I already had high impedance on both sides of the filter.  I put a .001 uF cap on the input side to keep the DC voltage off the filter (see above and below). This capacitor allows us to avoid the dreaded problem of electro-migration that is so nicely described by SV8YM here: 

http://sv8ym.blogspot.com/2010/07/mysterious-case-of-withering-filters.html. 

Tasos also provides a good description of the innards of those little black boxes that contain ceramic filters. 

Once you get the filter in your receiver, you have to carefully place the BFO signal in relation to the filter passband.  I have trouble properly sweeping 455 kHz filters -- my HP8640B will not go that low.  Nor will my Antuino (I need to modify the code -- someone help me please).  I know the NanoVNA will do the job, but I just couldn't seem to get it to work.  So I went "old-school" and manually swept the filter using my FeelTech sig gen and my Rigol scope.  This gave me a rough idea of where the passband was.  I put the BFO on the low end of the filter passband, at 451 kHz.

   

With this filter the MMM RX has become a real asset.   The 6 kHz bandwidth allows for nice reception of both SSB signals and AM sigs.   I may try to use one of the +/- 2 kHz filters  (4 KHz wide), but so far I have not been able to find a source for this part.