Putting the "Mate for the Mighty Midget" Back to Work -- With a DX-100 on 40 Meter AM

After working on it for a while I got so fond of my old Hammarlund HQ-100 that I moved it from the AM/Boatanchors operating position over to a more convenient spot right next to my computer.  This left a big gap on the receive side of the AM station.  

I briefly put my HRO-ish solid state receiver above the DX-100, but I'm afraid that receiver needs some work.  More on that in due course. 

I thought about putting my SOLID STATE Lafayette HA-600A atop the thermatronic DX-100, but this just didn't seem right. The Radio Gods would NOT approve. 

So I turned my attention to the Mate for the Mighty Midget that I built in 1998 and have been poking at and "improving" ever since. 

This receiver worked, but not quite right. It received SSB stations well enough, but when I turned off the BFO I could no longer hear the band noise. I wasn't sure how well the RF amp's grid and plate tuned circuits tracked.  And I had serious doubts about the detector circuit that Lew McCoy put in there when he designed this thing back in 1966. 

As I started this latest round of MMMRX poking, I realized that I now have test gear that I didn't have in 1998:  I now have a decent oscilloscope.  I have an HP-8640B signal generator (thanks Steve Silverman and Dave Bamford).  I have an AADE LC meter. And I've learned a lot about building rigs. 

FRONT END TRACKING

The MMRX has a tuned circuit in the grid of the RF amplifier, and another in the plate circuit of the RF amplifier.  There is a ganged capacitor that tunes them both.  They need to cover both 80/75 and 40 meters. And they need to "track" fairly well:  over the fairly broad range of 3.5 to 7.3 MHz they both need to be resonant at the same frequency.  

McCoy's article just called for "ten turns on a pill bottle" for the coils in these parallel LC circuits.  The link coils were 5 turns.  No data on inductance was given.  Armed now with an LC meter, I pulled these coils off the chassis and measured the inductances of the coils.  I just needed to make sure they were close in value.  They were: 

L1 was .858uH L2 was 2.709         L3 was .930uH  L4 was 2.672

Next I checked the ganged variable capacitors.  At first I found that one cap had a lot more capacitance than they other.  How could that be?  Then I remembered that I had installed trimmer caps across each of the ganged capacitors. Adjusting these trimmers (and leaving the caps connected to the grid of V1a and V2A, I adjusted the trimmers to get the caps close in value.  I think I ended up with them fairly close: 

C1: 63.77-532 pF          C2 64.81 -- 525.1 pF

I put the coils back in and checked the tracking on 40 and on 80/75.  While not perfect, it was close enough to stop messing with it.  

DETECTOR CIRCUIT

I've had my doubts about the detector circuit that Lew McCoy had in the MMMRX.  In his 1966 QST article he claimed that the circuit he used was a voltage doubler, and that this would boost signal strength.  But I built the thing in LT Spice and didn't notice any doubling.  And consider the capacitors he had at the input and output of the detector:  100 pF.  At 455 kHz 100 pF is about 3500 ohms.  At audio (1 kHz) it is 1.5 MILLION ohms. Ouch.  No wonder years ago I put a .1 uF cap across that output cap just to get the receiver working. 

Scott WA9WFA told me that by the time the MMMRX appeared in the 1969 ARRL handbook, the second "voltage doubling" diode was gone, as were the 100 pF caps.  Now it was just a diode, a .01 uF cap and a 470,000 ohm resistor.  I switched to the 1969 Handbook circuit (but I have not yet changed the 1 meg grid resister to 470k -- I don't think this will make much difference).  Foiled again by a faulty QST article, again by one of the League's luminaries. 

6U8s out, 6EA8s in 

We learned that the 6U8 tubes originally called for by Lew McCoy are getting old and not aging well.  So I switched all three to more youthful 6EA8s.  This seemed to perk the receiver up a bit. 

MUTING from the DX-100

My K2ZA DX-100 has a T/R relay mounted in a box on the back of the transmitter.  When the Plate switch goes up, it switches the antenna from receiver to transmitter.  The box also has a one pole double throw switch available for receiver muting.  I put the common connection to ground, the normally connected (receive position) connect the ground terminal of the AF output transformer to ground -- it is disconnected from ground on transmit.  The other connection (normally open) is connected to the antenna jack -- on transmit this connection ground the receiver RF input connection.  These two steps mutes the receiver very nicely. 

Replacing Reduction Drive

Over the years I have had several different reduction drives on the main tuning cap.  I had a kind of wonky Jackson brothers drive on there that needed to be replaced.  I put in a new one -- this smoothed out he tuning considerably. 

Ceramic Resonator

I never could get McCoy's 455 kc two crystal filter to work right.  So at first I made due with the two 455 kc IF cans.  This made for a very broad passband.  Then I put a CM filter in there.  This was more narrow, but with a lot of loss.  There may have been others.  But the filter spot is currently held by a 6 kHz wide ceramic filter.  This one is my favorite so far. 

Digital Readout

When I was running the DX-100 with the Hammarlund HQ-100 I built a little frequency readout box.  The box was from a Heath QF-1 Q multiplier (I am sorry about this).  The readouts are in Juliano Blue and come via e-bay from San Jian.  I now have it hooked up to the DX-100's oscillator.  I haven't tapped into the MMMRX's oscillator yet. 

Mike WU2D Looks at the "Dream" SW Receivers of the 1960s and 70s (Video)

Wow, I really liked Mike's walk down memory lane. I saw several of my own dream receivers: 

S-38E.  Indeed, this little monster did add some danger to your life.  AKA "The Widow Maker," I gave one to my cousin's husband so he could listen to what the commies on Radio Moscow were saying.  He later told me that the receiver had given him a shock.  I now have TWO S-38Es in my shack (two more than I really need).  I have installed isolation transformers in both of them, so they have lost the one element (danger!) that made them attractive.  

HA-600A. I got this one for Christmas in 1972.  The A model is MUCH better than the plain vanilla HA-600.  I recently got another HA-600A and found serious deficiencies in the Product Detector.  Has anyone else noticed these problems?  BACKGROUND INFO AND A PLEA FOR MORE INFO HERE: https://soldersmoke.blogspot.com/search?q=HA-600A+Product+Detector

HQ-100.  Got one in the Dominican Republic.  Fixed it up, repairing damages caused by radio life in the tropics.  Disabled the goofy audio amplifier circuitry.  I now wonder if this receiver might benefit from the insertion of a 455 kc ceramic filter. 

NC190.  Wow "Cosmic Blue"  Perhaps this was an early influence that led to "Juliano Blue?" 

HQ-180.  "18 tubes and almost as many knobs!"  FB!  

HRO-500.  Love the dial. 

Transoceanic.  Never had one, but built a BFO for the Transoceanic that W8NSA took with him to SE Asia during the war. 

R-390A.  I don't have a crane for the workbench.  

Thanks Mike -- that was a lot of fun.  

SolderSmoke Podcast #222 Antennas, Phasing, VFOs, 2-Bs, 6 years of N6QW, MAILBAG

After 46 years, finally a dial skirt

SolderSmoke Podcast #222 is available:  

http://soldersmoke.com/soldersmoke222.mp3

No travelogue but… SolderSmoke Almanac!

Memorial Day in U.S.

End of Ramadan so Eid Mubarak! 

#222 marks SIX YEARS of Julian-ismo.  He started on SS 161.  Thanks Pete. 

Thanks to all who sent good wishes on Billy's graduation.  He heads to Boston and the lab in a week or so.  Very proud. 

------------------------------------------

Bill was on Ham Radio WorkBench Podcast  

 ----------------------------------------- 

PETE'S WORKBENCH

-- Antenna Ideas -- Don't Buy that $165 dollar dipole!  It is just wire!   

-- THE PHASING RIG. Does this point to a need for meditation?  Or at least some temporary disengagement? Tribal wisdom from Pete. 

-- DEAN KK4DAS's rig.  The Furlough 40.  Troubleshoot.  Tribal knowledge. 

-------------------------------------------

-- SHAMELESS COMMERCE DIVISION:   AMAZON BOX -- SEARCH FOR ANYTHING OU WANT THERE.  

-- PLEASE PUT COMMENTS ON THE SOLDERSMOKE BLOG POSTS. 

-- PLEASE CHECK OUT THE SolderSmoke YOUTUBE VIDEOS. 

------------------------------------------

BILL's WORKBENCH

n  Shortwave dials and exotic locations.  Java!  

n  Galaxy V VFO Project. Series-tuned Colpitts.  

n  DRAKE 2-B.  Hayseed Recap. Put the skirt back on the old rig.  Reduction drives?   

SHOPPING BAG: 

I got a replacement for the Xtronics 4000 soldering station.  Yaogong worked! 

https://www.amazon.com/gp/product/B078WB9Z2R/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1  

Ordered screws and stuff from McMaster -- Came very fast! 

Working on a resistor kit from Mouser. 

MAILBAG: 

VK2BLQ's Phasing RX with an HRO dial.  Cool Retro.  

Adam N0ZIB -- Cool station.  TFT screen Aluminum welded box. FB. 

Karl G7AFT    BITX 40 doing USB and LSB by changing the VFO freq.  Pete's trick! 

Jerry KI4IO  out in nearby Warrenton.   Hope to be able to meet up soon. 

Keith N6ORS's Hot Mustard Phasing Board. 

Mike N5GTF'd FULLY INDOOR Quarantine Receiver.  Need a slogan for the antenna!

Nick M0NTV's Bread Bin 80 Quarantine rig

Bruce KC1FSZ   Quarantine 10 -- Brave man in solar minimum. But I hear 10 is opening.

Talking to Grayson Evans KJ7UM  TA2ZGE about Collins 9.9 MHz transformers.

Talking to Alan Wolke W2AEW about Drake 2-B stuff  Was there a reduction drive?

Paul VK3HN about Ceramic filter spurs.

Peter VK2EMU notes no animals were harmed in the making of my videos.  But many electrons were agitated. 

N6QW Phase Shift Success -- It aint over 'till the fat lady sings

I,Q, and HRO: VK2BLQ's Phasing Receiver with an HRO Dial

I had occasionally fantasized about connecting Armand's HRO dial to the rotary encoder of an Si5351, but I think this was more of a nightmare than a fantasy.   I don't think Stephen VK2BLQ went this far -- I suspect that his HRO dial was connected to an analog VFO.  But still, the combination of HRO with I&Q seems a bit edgy...  FB Stephen.  Please send us more info on this amazing receiver. 

  

Hi Bill,

Hope you are safe there with the bad weather.

Recently you  mentioned HRO dials and the need to build a radio around one and Pete has been discussing phasing SSB; attached photo is a phasing receiver on 80 and 40 m, a combination of both HRO and IQ that I built many years ago, and thanks to Pete I shall get it running again.

And Bill, like you I am from the IGY of 1958 and retired with more free time on my hands.

Best regards to you and your family, especially young Billy.

Stephen,

VK2BLQ

SolderSmoke Podcast #220 -- S-38Es, AD9833s, Pete's Phasing Rig, FT-8

Java on the S-38E Tuning Dial

SolderSmoke Podcast #220 is available

http://soldersmoke.com/soldersmoke220.mp3

Hunkered Down.  StayInTheShack:  SITS!  Flatten the Curve!  It is working.

Teaching English again – via Zoom.  Kids completing the school year remotely.  

BILL'S BENCH

-- Finishing up on the S-38Es.

  

-- I wrote up my alignment, isolation and dial string experiences.

-- SWL  WRMI Radio Miami International on 39 meters 9.4-9.9 MHz.  Rock and Roll.

-- S-38E work is causing me some serious legal problems.  They are threatening to take down our sites and our podcast.   Google has put a CEASE AND DESIST ORDER on my blog:   Check it out http://soldersmoke.com/CEASEANDDESIST.JPG

--S-38E caused me to want to get my HRO dial receiver on the SW broadcast bands with a good AM detector.  

-- Next up: Hayseed Hamfest cap for my Drake 2-B.  And I have an idea on how to easily broaden it for AM:  Tap the 455 kc output on the Q multiplier jack.  455 AM detector to audio amp. 

SHAMELESS COMMERCE DIVISION

PETE’S BENCH

AD9833

Phasing Rig Project

.

DEAN’S PROJECT – Step by step.  Trouble shooting.  Understanding.  Receiver triumph.  FB.

MAILBAG

Jack 5B/AI4SV doing well in Cyprus

Daniel SA7DER listens during commute in Sweeden.

Peter VK2EMU building a 6 meter amp.  With Tubes

Jim WA8ZHN  says there are still 7751 Novices on the books.   FB.

Mike WB2BLJ modding his BITX – having a lot of fun.

Fred KC5RT – Great idea on isolation transformer in my S-38E.  

Jerry Palsson: S-38C's curves vs. S-38E's exotic places.  Java. 

Krakatoa East of Java

The Year of Living Dangerously

Anonymous mail:  FT-8 DX -- Are these contacts legitimate? See below. 

Dear Bill and Pete: 

I've been meaning to share with you something that has come to my attention by a rather circuitous route. 

As you guys know, I've been involved in the software/IT side of ham radio for many years. I've watched many digital modes come and go.  I've always enjoyed my work, but lately I've seen something that makes me uneasy. 

I'm sure you guys have heard of the fantastic DX that is being worked by many guys using FT-8.  It seems like all they need to work Jakarta is a couple of watts to a wet noodle. Shazam!  Contact! 

Well, I learned something that calls into some question the legitimacy of many of these contacts....  

As i understand it, certain manufacturers, in cahoots with a major American ham radio organization (that happens to be very dependent on ad revenue from that manufacturer), have secretly set up a system that combines the internet and ham radio. 

Here is how it works:  Suppose Joe Ham gets on FT-8 on 40 meters.  He puts out a call using his QRP transmitter and the aforementioned wet noodle.  No way that signal is going to Jakarta, right?  Well, it will with a bit of help.  

The system has SDR transceivers  and great antennas set up at strategic points around the world -- these are really great locations -- think mountain tops near the coastlines, always with high speed internet T5 connections. I think this is part of the whole “contest superstation for on-line lease” business model.  

One of these stations picks up Joe Ham's FT-8 call. Sometimes it will just re-transmit it, sometimes is will send it to a counterpart station on the other side of the globe.  Bingo, Joe Ham's signal is suddenly in Jakarta.  A station there enthusiastically responds, and that signal goes back with the same kind of repeater/ internet assist.  This is all done out of the reach of the FCC.  They are usig overseas locations,  some of them in Mexico.

Of course they have to be careful not to "facilitate" these kinds of contacts during times in which the bands are obviously dead,  That's why 40 is so useful for this system.  Obviously they can't keep this kind of thing secret forever -- they just want to get guys hooked on FT-8, then they can reveal the system, selling it as nothing unusual, you know, sort of akin to Echolink.  

Of course, this hasn't been made public (for obvious reasons!) but I can tell you the name of the system:   They tried to make it sound like something familiar (in this case like APRS): They call it  "Automatic Private Radio Internet Link 1."  My understanding is that when they do their “roll out” they will offer the new service to those willing to pay a subscription.

Obviously as an old-school, traditional ham, I'm troubled by all this.  What do you guys think?  I wonder what your listeners would think. 

Please don't mention my name..  But here is a site that describes the new system: 

http://www.automaticprivateradiointernetlink1.com/

Thanks and 73... 

Please let us know if you have any information on this, or have observed any unusual and suspicious success with FT-8.

Radio History Question: Why 455 kHz as the IF frequency?

My work on the S-38Es, on the HRO-dial receiver, on the Mate for the Mighty Midget,  and on various mechanical filters has caused me to think (once again) about why we ended up with 455 kHz as the  IF frequency for so many radios.  I've heard many explanations for this, but unfortunately I've forgotten the explanations and lost the sources.  I started digging into this again today.  I found the below e-mail from Al N3FRQ on the Boatanchors mailing list (2008). 

I contacted Al to find out if he had learned anything else on this topic.  He has not.  So if anyone out there has answers to Al's questions, or anyother info that would shed light on why they went with 455, please let us know. 

------------------------------- 

Every so often the question comes up: Why are all the IF’s 455 KHz? I’d 
like to get an article together that solves this riddle while the people 
who know are still with us. I know parts of the story, but I need help 
with a couple of issues.

There are two major consideration is the choice of the intermediate 
frequency used in a superheterodyne receiver. The lower the frequency, 
the easier it is to attain high selectivity. Also, in the early days, 
before tetrode and pentode tubes, it was easier to achieve a high degree 
of amplification at lower frequencies. Conversely, a higher IF frequency 
results in better image rejection.

Early superhets had the IF at 100KHz or lower in order to get adequate 
gain from the available triode tubes. They suffer severely from 
“two-spot tuning” (images). By the early 1930’s, broadcast set had 
settled in at 175KHz, and automobile receivers would later adopt 262KHz 
as a standard.

The advent of the short-wave craze, and multi-band broadcast receivers 
dictated a higher IF frequency to achieve adequate image suppression on 
the short-wave bands. The broadcast band occupied 550-1500KHz at this 
time, and the designer encounters sever problems if his radio tunes 
across it’s own IF. Some shortwave sets used 1600-1700KHz for better 
image rejection, but one couldn’t go higher if the 160-meter ham band 
(1800-2000KHZ) was to be covered. Most multi-band receiver settled in 
near 450KHz, a comfortable distance from the first broadcast channel at 
550KHz.

Questions:

Odd multiples of 5KHz, 455, 465, etc., were usually chosen so that the 
image of the carrier of a broadcast-band station could be zero-beat with 
the carrier of the station being tuned to achieve minimal interference. 
(This assumes 10KHz channel spacing. Did the Europeans (9KHz) do 
something else?)

The Radiotron Designers Handbook, Third Edition, p. 159, states “A 
frequency of 455 Kc/s is receiving universal acceptance as a standard 
frequency, and efforts are being made to maintain this frequency free 
from radio interference.”

(1) Do FCC and international frequency allocations reflect this?

(2) I’ve heard the term “Clear-Channel IF.” Can anyone cite references?

(3) At lease one news group posting claims that broadcast frequencies in 
a particular market are assigned to prevent strong inter-modulation 
products from falling near 455KHz. Is this factual? Need reference.”

(4) Was this (3) at least part of the reason for “Radio Moving Day” in 
1941? See: http://www.dcmemories.com/RadioMovingDay/032341WINXFreqChange.jpg

(5) Many National Radio sets used a 456KHz IF’s and I think I remember a 
437 somewhere. Why? Are there different considerations for short-wave CW 
operation?

Further input, corrections, and elaborations are greatly appreciated. 
Scolarly reference will be looked upon with great favor.

Regards,
Al

-- 
Al Klase - N3FRQ 
Flemington, NJ 
http://www.skywaves.ar88.net/

AM Diode Detector + 41 and 49 meter Shortwave Bands for HRO-dial Receiver (videos)

The COVID-19 emergency is a good time to look around the shack for projects you have been meaning to take on but didn't have the time for.  We have the time for them now! 

When I first built my HRO-dial receiver (using an HRO dial given to me by Armand WA1UQO and an enclosure from Tim KI6BGE)  my hope was to have the 40 meter ham band and some shortwave broadcast bands.  But it didn't work out that way.  I had trouble getting an AM detector to work properly, and I had a hard time getting a sufficiently broad filter to work right.  I ended up adjusting the VFO so that the receiver would cover only the 40 meter ham band.  

My recent S-38E adventures and a video from VK3HN have alerted me to the nice programming that is now on the shortwave broadcast bands (I really like WRMI's afternoon rock music program).  So I decided to take another shot at getting this receiver to cover SW BC frequencies. 

When I built this receiver, I made the front-end bandpass filter tune-able. There is a two section variable cap behind that "Pre-selector" control you see on the front panel.  That lets me tune two loosely coupled LC circuits from about 5.5 to about 8 MHz.  So without any mods to the front end, I could cover the 49 meter band (5.9 -- 6.2 MHz) our 40 meter band, and the 41 meter band (7.2-7.5 MHz)

Here is how I do it: 

For 49 meters:  I now have the VFO set to run from 6.34 MHz to 7.120 MHz.  The IF is .455 Mhz.  So to get down to the lowest frequency in the 49 meter band, I tune that front end preselector down to that frequency (variable cap in filter almost fully meshed).  Then I take the VFO down to 6.355 Mhz.  I take the difference frequency out of the mixer -- .455 MHz.  

For 40 and 41 meters:  I just tune the pre-selector to this range (variable cap about mid-range) and tune the VFO accordingly.   For a signal at 7.5 MHz, for example, I put the VFO at 7.045 MHz.  7.5 - 7.045 = .455 Mhz.  Note:  There is no sideband inversion in this case -- this is important because 40 meter SSB is lower sideband.  The Kokusai mechanical filter that Pete N6QW gave me is a lower sideband filter.  I have my BFO set at the right spot relative to the filter passband for LSB.

As you can see, I just tune to the "image frequencies" with the preselector.  This gives me double the frequency coverage.   

As for the filters, well Pete's Kokusai filter works great on 40 SSB.  My problem was,  ironically, getting a filter that was broad enough to let AM sound good.  I concocted a filter using old 455 kc IF cans, but I wasn't happy with it.  Paul VK3HN used a ceramic .455 MHz filter that was 6 kHz wide at 6 db down. I ordered some from Australia.  That should have been wide enough for AM, but I had gotten spoiled by the very WIDE bandwidth of my S-38Es (no real filters at all, just the two 455 kc IF cans).  At this point The Radio Gods interceded. Bruce KK0S heard me talking about this on the podcast and kindly sent me some 10 kHz .455 kHz filters.  Now we're talking!  I put one of them in this receiver and AM started sounding as good as it does in my S-38E.  BTW -- a look at NA5B's WebSDR receiver shows that most of the SW broadcast stations are running at 10 kHz wide.  See video below: 




Finally,  I had to get a decent AM detector going.   The SBL-1 product detector I have in there works great, but I had tried several AM detectors and none of them worked well for me.  This was puzzling -- it should be so simple, right?  Just a diode.  But I would get weak and/or distorted audio.  I realized that I really needed was something that looked to the rest of the circuitry like an SBL-1, but with just a diode and an RC filter section instead of the SBL-1's diode ring.  I ended up using a small 455 kc IF transformer that Michael Rainey (AA1TJ) had sent me a long time ago.  My detector looks like this: 

It works great.  During the day I can hear the Toronto CFRX talk-radio station that simulcasts with 1 kW on 6.07 MHz. In the evening I her WBCQ and many other stations on 41 meters (see videos).  And of course I am ready to use it for amateur AM signals on the high end of the 40 meter phone band.   

There is a lot of soul and friendship in this receiver: 

-- HRO dial from Armand WA1UQO

-- Aluminum box from Tim Sutton KI6BGE

-- Mechanical Filter from Pete N6QW

-- IF transformer from Michael AA1TJ

-- Ceramic filter from Bruce KK0S

-- 10k pot in the detector from Thomas KK6AHT

-- Inspiration and ideas from Paul VK3HN

-- Many parts from Jim... 

But you know, I find myself thinking that there are many stations I like on the 39 meter band.  I think it might be best to build a separate receiver for those frequencies.  Maybe throw in 30 meters.  Hmm, let me see what's in the junk box... 
 

Will, KF4IZE's Beautiful Boatanchors

Wow, check out the paint job on that SP-600.  Nice work Will.  Hammarlund should have done it that way.  And I should have kept the one I had years ago.  I would have painted mine that way.  

And my DX-100 (given to me by John K2ZA) has similar vernier reduction drives. 

I run into Will KF4FZE fairly often on 40 meters.  He and I were in the same (very cool) part of the U.S. Army (in different times).  Will is retired but he still works at Ft. Bragg. 

I heard Will on 40 SSB yesterday afternoon.  I was listening with my HRO dial receiver (that I am now working on).  I shot quick video: 

Will was on a Swan Cygnet 270 that he had recently picked up on e-bay.  

More on Will KF4IZE here: https://www.qrz.com/lookup/d/kf4ize

SolderSmoke Podcast #217 -- Beach trip, '30s station, uBITX mods, HRO RX AM, ELMAC, Teensy, MAILBAG

Bill's Bavaro DR Beach Station
uBITX in the box, HB key

SolderSmoke Podcast #217 is available: 

http://soldersmoke.com/soldersmoke217.mp3

1 February 2020

Travelogue!  Dominican Republic trip.  uBITX on the Beach.  EFHW.  LiPo Battery.  First contact of the new year. 

Bill's Bench Report

Following up on proposed uBITX mods: 

-- Put pot on sidetone line from Raduino to keep the sidetone a bit quieter. 

-- Fixed the key -- pounding brass

-- Will install 4 States QRP Active AF filter. 

-- Need to reduce power on CW to 5W

-- Stereo to mono headphone adapters. 

-- Turning off display and mic amp circuit not really worth it -- they don't pull much current. 

Pete's Bench Report: 

ELMAC Power Supply project 

1930s era transmitter? 

Teensy and SDR

PETE'S IDEA ABOUT GETTING LSB AND USB FROM BITX40

KWM-2 suggestions

Back to Bill's Bench:

Working on HRO-ish Receiver. 

Bad SBL-1  

Got idea for wider ceramic filter from Paul VK3HN

Ordered parts from Mini-kits in Australia.  They sent 6kc filters. 

Bruce KK0S sent me some 10 kc filters too. 

Installed 6 kc filter with L network matching networks.  Works great. 

Also installed Infinite Impedance Detector that Paul used. 

Needed some additional amplification ahead of the IID, so I used one stage of BITX amp. 

Works great. I can tune full 40 meter band AND 49 meter SW band.  Radio Romania, China, Radio Marti, Brazil, South Carolina. 

Beefed up the shielding to cut down on AM detection. 

MISCELLANY

-- AM and DSB in LTSpice

-- Duly Noted:  Paul  VK3HN's RIG:  "THIS MACHINE KILLS KILOWATTS"  

Kanji YC3KNJ's QRPesso Expresso Coffee in the field

-- The DANGERS of powerful magnets. 

MAILBAG: 

--KK4DAS Dean doing great things.   MMM heard at Penn State.  Where is the rest of the CBLA?

-- Thanks to Don for kind donation to the SolderSmoke cause

-- Dale BA4TB -- First SolderSmoke feedback from China.  Thanks Dale!  

--Steve Silverman:  Sideswipers and bugs were made to handle "carpal tunnel of the day"  So do I need a keyer for casual CW work? 

-- Peter VK8VWA on the limited knowledge gained from kit building. Listens to podcast while walking on the beach in Australia. 

-- Allan Hale -- Clothes Pins as Toroid holders.  Yes!  More Clothes Pins   Wild Woody Keys from Dave Ingram 

-- Pete WB9FLW  100 Watt Amp from WA2EUJ  

-- Dave Wilcox K8WPE   A medical question:  Does the Michigan Mighty Mite work differently depending on what kind of medicine was in the pill bottles used for the coil form?  Good question Doc!   Dave suggest that putting CBD on the coil or the crystals.   Anything to mellow out the ham bands... 

Pete's Plank SDR
When you know stuff, you can do stuff!

VK3HN's Inspirational AM Receiver (video)

I'm always delighted when I check the SolderSmoke blog and YouTube list (right hand column of the blog) and find a new post from Paul VK3HN.  And this morning's post is especially good. 

Paul has built an AM receiver. Above you can see his video.  Here is his blog post with details: 
https://vk3hn.wordpress.com/2019/12/06/8-band-superhet-am-receiver/

This is the kind of blog post that makes you want to heat up the soldering iron and start searching through the junk box.  I'm thinking about putting Paul's 6 kHz filter in my 40 meter HRO-ish receiver.  And I may make use of his AM detector circuit.  And maybe I can put that same receiver on 75 and 160... And then there are the SW broadcast bands... See what I mean?  

Thanks Paul.  73  

The Collins Mechanical Filter -- An Advertisement from Australia, 1963

Peter VK2EMU sent me this ad a while back.  He said he regretted being unable to send a filter -- all he could send was the ad.  Thanks Peter -- I think that ad is a work of art.  Radio art. 

Thanks too to all those who sent me mechanical filters.  Pete sent the first one (it is currently in my HRO-ish receiver), then two more (both inside SBE transceivers, where they will remain -- it would be a sin to cannibalize those beautiful rigs.)  Then Mike Herr WA6ARA sent one as did Brad.    Brad assures me that the one he sent was boxed up by Art Collins himself! 

Thanks again guys. 

Brad wrote: 

To:soldersmoke@yahoo.com

Jun 23 at 7:49 AM

Kudos to Pete for 60 years! And I've always thought he was much younger than you......

Catching up on your podcast, I was surprised to learn that no one answered your call for a spare filter.  

I'm one of those older guys who is making his way back after leaving amateur radio in 1968 for girls and/or recreational drugs.

No one told me that The Force (electro-motive, that is) would require me to catch up on all the junk I would have acquired during my nearly 50 years away from the hobby (see list below).

A recent impulse purchase, the most beautiful thing with tubes ever made (SX-42), happened to be near Newington.  On the way home I visited ARRL HQ hoping they had some sort of a chapel where I could perform an act of penance and ask for guidance in dealing with my affliction.   Apparently, this is the equivalent of asking a crack dealer where the closest Narcotics Anonymous meeting is held. I ended up buying a copy of "200 Meters and Down" and have since acquired a couple of Atwater Kent projects. 

My place is full now, and my sweetheart would like back the half of her garage I've slowly taken by electronic eminent domain.   It seems that for every 100 pounds that departs to a ham fest, 125 pounds comes back.  Is this considered a normal ratio?

In order to be able to tell her that I have, indeed, gotten rid of something, I'll be sending you a F 455 filter (QRZ address OK?).

Thanks for you help,

--Brad 

A Beautiful Variable Capacitor (from Pete)

Is this a thing of beauty, or what?   Pete sent this to me back when I was having trouble finding a "smooth running" variable cap for my HRO dial receiver.  It has a standard Jackson Brother's reduction drive attached to the shaft, followed by a really cool gear arrangement.  Note the spring loaded teeth on the big gear -- that is to keep the gears tight when turning in both directions.  

As was the case with the HRO dial that Armand sent me, the beauty of this part will cause me to build something with it, really just for the purpose of putting it to use. We've been talking about double or triple conversion superhets with 100 or 50 kHz final IFs.  At those frequencies you can get good selectivity with LC filters.  As with the Drake 2-B.    Steve N8NM is sending me a dial that will go well with this part.  That will add to the already abundant mojo/juju.  I feel a VFO in the works.    Thanks to Pete for being so supportive of my luddite analogism.  

SolderSmoke Podcast #210 Boatanchors, Magnetostriction, VFOs, AM, CW, SSB, Mailbag

2 March 2019 

SolderSmoke Podcast #210 is available: 

http://soldersmoke.com/soldersmoke210.mp3

Alexa, Marie Kondo, berets, and ham radio

Bi-Coastal Boatanchors
BATTLE CRY: The Vintage SSB Preamble! "We are NOT ashamed!" 
Bill's HT37 and Drake 2B 
Pete's National National NCX-3  TRGHS
Mechanical Filters
Magnetostriction
Why did Collins go with mechanical vice crystal filters? 
The foam deterioration syndrome in mechanical filters.  Sad. 
Please send any unwanted Mechanical Filters to Bill. 
BONUS QUESTION:   Look at the filter below.  What is different/special about this one?

Pete's antenna trouble
Pete's FB amplifier troubleshooting
Recent improvements in the uBITX finals
Pete's design for a VFO for Bill (and an indoor antenna tuner!)

Bill's VFO for Pete:  HRO dial and gearbox driving a rotary encoder

Guido PE1NNZ puts the QCX on SSB
"The Secret Life of Machines -- Radio"
HB HRO dial from DL6WD
WA1QIX's USB D-104
"The High Frequency Oracle" 
DeMaw's LC filter receiver
Godzilla and Ham Radio
Bill's poor quality SSTV images from space (what happened?) 
Listening to AM on an SSB receiver
Mixed feelings about CW 

MAILBAG
M0KOV's mom took him to the doctor due to THE KNACK. 
M0JGH getting married (ALWAYS LISTEN TO PETE!) 
Jac's FB Receiver

What is different/special about this one?

A Homebrew HRO Dial by DL6WD, Homebrew Hero

Take a look at that beautiful rig in the bottom of the cover pictures. (A closer shot appears below.)  That is an HRO dial, right?  Or is it?  

No, it is not.  In the picture we see the homebrew receiver designed and built during the 1960s by Rudolf Fishcer, DL6WD.  It is magnificent in every respect.  Because I have been working with the HRO dial and gearbox given to me by Armand WA1UQO, the tuning dial on this receiver caught my attention. 

Here is what DL6WD says about this part of his project:  "The main tuning gear was built around a BC-221 tuning capacitor and reduction gear. The counter dial and tuning knob are the result of four weeks of labor, The counter dial reads in tens of kHz, where the main tuning knob has a calibration of 200 Hz per division, from an HRO inspiration."  The counter is in the little window to the upper left of the tuning knob. The window to the upper right is a phase-lock indicator. (See below.)

By the way, by the time DL6WD got finished with this all solid state receiver it weighed in at 52 pounds.  Rudolf noted that "excessive shielding pays in electrical performance, but not in weight!" 

DL6WD earns the title "Homebrew Hero."