Troubleshooting and Fixing Old Faults in my Long-Suffering Hammarlund HQ-100 (Part 2) (video)

Work continues on my old Hammarlund HQ-100. I give background on the rig and explain the electrical trauma it likely suffered. Following Dave K8WPE's dictum that we can still learn a lot from old receivers, I dug into this one. I wanted to fix a long-standing S-Meter/AVC problem. This led me to an interesting troubleshoot, with at least one "waste of time" detour. Eventually I found the fault in one of the coils in the grid circuit of the RF amplifier. The coils had been smoked years ago, perhaps by a lightning strike. I came perilously close to permanently losing 10-30 MHz. But I figured out how to fix the smoked coil. So my S-Meter/AVC problem was fixed. I really like listening to this thing. There is still a lot of nice material on the SW bands. There are some very nice broadcasts in Spanish. Please subscribe to my YouTube channel.

You can see where the coil burned. Wire remained intact, but the insulation burned creating a Primary to Secondary connection.

I just very carefully lifted one of the coils way from the other, eliminating the unwanted connection.

Here's my homebrew "RC Printed Network" Z2 module. This was unnecessary -- the original was good. I put the original back in.

Electric Radio magazine recently ran a two part series on the HQ-100. I have ordered these issues of the magazine.

Working On My Old Hammarlund HQ-100 (Part 1)

I like this old receiver, with all its shortcomings.  I picked it up in the Dominican Republic in 1993 or 1994.  I've been using it on AM with my K2ZA DX-100.   It needed some contact cleaner, and I took the opportunity to work on a few of the circuits that were getting kind of decrepit. 

I came to a new understanding of -- and appreciation for -- the Q-multiplier.

While of similar vintage, this receiver is MUCH nicer than the Hallicrafters S-38E: 

S-38E 1957-61 $54.95 5 tubes.  AC/DC, kind of flimsy. 

HQ-100 1956-60 $169  10 or 11 tubes.  Power supply,  regulator,  much sturdier construction

You get what you pay for.   

 In Part II I'll show you how this thing sounds and what it is like to use it for SWL, CW, SSB and AM. 

Looking at the World Through a 1 inch Cathode Ray Tube (the RCA 913) (videos)

Joh DL6ID sent me the above video.  We have been e-mailing each other about the W9YEI Television Receiver built in 1939 or so.  We have kind of concluded that the builder used an RCA 913 tube as the CRT.  This was an oscilloscope tube and was often described as looking like a metal 6L6 with a tiny screen on top.   This is kind of neat -- like using something from the old days to peer into the new world of video.  

We wondered about the image persistence of this tube.  Fortunately for us, we found several YouTube videos showing recent builds or repairs of oscilloscopes with RCA 913 tubes.  

Of course, Mr. Carlson has a video on one of these devices (and -- as expected -- has another in his junk box.  Mr. Carlson has at least two of everything.) 

Here are a few other videos showing RCA 913 tubes in action. 

https://www.youtube.com/watch?v=1-qidcmN-sI

https://www.youtube.com/watch?v=IfN2mmEIfTE   (with Men at Work audio)

https://www.youtube.com/watch?v=TJF22Ra2kIM    (Summertime.... And the Livin' is Easy)

Here's a nice video from Tektronix on CRTs: 

https://www.youtube.com/watch?v=jHGAnJjnNY0

1942 (?) RCA Film on Tubes, Radio, Research, and Television

Here is a very interesting video from RCA.   It was released in 1942,  but it looks to me as if it was produced BEFORE the Pearl Harbor attack and the U.S. entry into World War II.   There is no mention of the war nor of RCA's support for the war effort.  All films like this that were produced during the war have a lot of material about how the company was contributing to the war effort.  So I think this is really a pre-war film. 

Early in the film they link the origins of RCA Labs to a decrepit "radio shack" at Riverhead, Long Island (NY) in 1919.   Here is some background on this: 

https://antiquewireless.org/wp-content/uploads/30-the_beginnings_of_radio_central.pdf

and

https://antiquewireless.org/wp-content/uploads/26-report_from_radio_central.pdf

In this film we see Vladimir Zworykin (boo, hiss) of TV fame (no mention of poor Philo Farnsworth),  and we also see Harold Beverage, the creator of the antenna that bears his name.   There is what must have been one of the first "electronic clocks."  

At the end, the segment on television is really interesting.   It is amazing how far they had gone with TV before the war.  

Young Jean Shepherd Gets Hung-Up On Ham Radio

Oh man, we've all been there:  OBSESSION with ham radio.  Shep went over the top and didn't sleep all weekend when his homebrew transmitter was finally neutralized and started to put out a decent signal on 40 meter CW.  

One of my favorite lines in this episode is about how, before the neutralization, the transmitter had had so many parasitics that it would continue to transmit for two hours AFTER Shep turned it off, "and all on the wrong frequencies."  

I found this while searching for other Shep references to Johnny Anderson, the guy who built the TV receiver.  Please let me know if you know of any other Shep references to Johnny. 

Here is the program.  Skip ahead to 20:50 

https://www.radioechoes.com/?page=play_download&mode=play&dl_mp3folder=T&dl_file=the_jean_shepherd_show_1963-03-07_hung_up-ham_radio.mp3&dl_series=The%20Jean%20Shepherd%20Show&dl_title=Hung%20Up-Ham%20Radio&dl_date=1963.03.07&dl_size=8.87%20MB

EXCELSIOR!  

"Patrolling the Ether" WWII Video on Radio Direction Finding Efforts

I heard about this video while trying to track down information on John Stanley Anderson's 1939 television receiver.  "Patrolling the Ether" is kind of hard to find.  It is not really on YouTube.  But there is a good BARC Vimeo video about WWII RDF efforts that includes at the end the full "Patrolling the Ether" video.  

Here it is:  

https://vimeo.com/415926991

Thanks to BARC and to Brian Harrison for putting this together. 

In the video, they discuss the invention of the Panadaptor by Dr. Marcel Wallace F3HM  during World War II.   I set up a very crude Panadaptor using Wallace's principals:

https://soldersmoke.blogspot.com/2019/05/diy-waterfall-quick-and-easy-panadaptor.html

The Vacuum Tube's Forgotten Rival: The Magnetic Amplifier

The video above shows one application of the principal, but be sure to check out the IEEE article:  

https://spectrum.ieee.org/the-vacuum-tubes-forgotten-rival

VK2BLQ's Two-Tube Regen with a SolderSmoke Dial

 

Thanks to Peter Marks VK3TPM ("a bloke with too many hobbies") for alerting us to this magnificent homebrew receiver with the especially magnificent tuning dial.   

http://blog.marxy.org/2022/03/a-two-valve-regenerative-receiver-for.html 

We have used old CDs as dials for many years.  I have one on my Q-31 Quarantine SW receiver.  But never have we seen one with SolderSmoke emblazoned on it. FB OM. 

Stephen VK2BLQ should make sure that those 6U8s haven't gone old on him.  I recently replaced the 6U8s in my Mate for the Mighty Midget with 6EA8s.  This seemed to rejuvenate the receiver.  

Also, it is shame that Stephen doesn't keep that rig at 12 volts.  250 V?  Yikes.  As I often say, you CAN hurt yourself with 12 volts, but you really have to work at it.  Not so with 250 V.   One hand behind your back Stephen! 

Thanks to Peter and Stephen. 

LA6NCA Designs and Builds a Very Hybrid 80 Meter Transmitter (Si5351 and a 12A6 Tube) (Video)

Helge LA6NCA put out a really nice video explaining how he designed and built an 80 meter transmitter. 

I like how he put the Si5351 and the Arduino chip in what looks like a slightly expanded FT-241 crystal box.  Nice.  

I like the box and the chassis.  

I like his testing/tuning technique.  

The homebrew capacitor was a very nice touch.  

Where can I get some of those coil forms?  

And of course, the R-390 receiver adds a lot of mojo to the shack. 

Helge's web sites document an enormous number of great projects:  

Helge's page on the 12A6/Si5351 transmitter: https://www.la6nca.net/homebrew/tx_12a6/index.htm

Helge's main site:  http://www.laud.no/fykse/index.htm

Thank you Helge! And thanks to Hack-A-Day for alerting us to this. 

A Thermatron (and Asperger's) Knack Story

Heroic stuff.  In more ways than one.  FB Mark.  

 https://www.aane.org/over-and-out/

6EA8s in the Mate for the Mighty Midget, and WA9WFA Re-Builds a Heath HW-12

I reported to Scott and Grayson that I had finally gotten around to changing the three aging 6U8 tubes in my Mate for the Mighty Midget receiver.  I replaced them with three more youthful 6EA8s.  This switch really seemed to perk up the old receiver.   I'm listening to 75 meters on it right now. 

Speaking of 75 meters, Scott sent me this picture of his latest effort:  re-building a Heathkit HW-12.  FB.  This is a way of experiencing (or re-experiencing) the construction of a Heathkit.  I did something similar, but much less complicated)  with a Heathkit VF-1.  Scott did a wonderful job taking this old rig apart.  That PC board looks great (see photo below). 

Scott's e-mail:  

Hi Bill and Grayson, I’m glad to hear of your good results with the 6EA8’s in your MMMrx! I had similar results when I finally got rid of the 6U8’s with their iffy performance and went with the 6EA8’s.  I did put a set of 6GH8A’s and tried it out, it worked, but I don’t have any data on performance improvements.  After completing the outboard power supply and audio amplifier, I’ve taken a break from my MMMRx and it’s sitting there on the bench. I’ll get back to it in a while.  

 

In the meantime I’ve started a new project where I’m re-kitting a Heathkit HW-12 eighty meter transceiver.  I have completed the disassembly process including the pcb.  I bought a Hakko vacuum desoldering iron for taking all (ALL) parts off of the pcb, and it’s bare now.   I’m planning to start rebuilding this coming week.  73 Scott WA9WFA  

1BCG -- The 100th Anniversary of the Trans-Atlantic Test

Thanks to the Antique Wireless Association for this really wonderful video, and for their involvement in the 100th anniversary event.  Special thanks to Ed K2MP. 

On December 11, 2021, the 1BCG team in Connecticut had some technical difficulties.  As we all know, that is part of being a radio amateur. Details of the problems are presented here: 

http://1bcg.org/1BCG/the-special-event-transmitter/

Phil W1PJE managed to hear and record some of the 2021 transmission (Thanks Phil).  Listen here: 

https://drive.google.com/file/d/1uPvD9Qh-VJTnyDzOPPSrYfbksks8sQsx/view?usp=sharing

Phil also sent this spectrogram of the signal. 

Good thing Paul Godley ran into Harold Beverage on the ship going over. 

And imagine me complaining about having to step out into the carport to adjust my antenna -- Godley had to trek one mile THROUGH SEA-WEED to adjust his.  Respect.   

Gloria -- A Netflix Series about a Shortwave Broadcast Station in Portugal

Rarely if ever will we come across a high quality NETFLIX series built around a shortwave broadcast transmitter.  But that is what we have in Gloria.    It is really good.  We were especially interested in it because we lived in Portugal for three years. In addition to all the intrigue and drama you will catch glimpses of broadcast antennas, big transmitting tubes,  and one out-of-focus shot of what appears to be a Hallicrafters receiver (SX-42?)   

More info here: 

https://www.forbes.com/sites/sheenascott/2021/11/13/gloria-netflixs-first-original-series-from-portugal-is-a-great-spy-thriller/?sh=446cef9b30d7

Here's the NETFLIX link: 

https://www.netflix.com/title/81073977

Thanks to Thomas K4SWL of SWLing Post for the heads up. 

KG7TR's Magnificent 75S-2B Receiver -- Tubes, an Si5351, an Arduino, a Bit of Collins, and a Bit of a Drake 2-B

 

Oh man, I share this with much trepidation because the last time I posted something about the work of Mike KG7TR,  Pete N6QW said he felt like putting all of his own work in the dumpster, so much better was the artistry of KG7TR.  This receiver is so cool and so well-done that we now  might have to post a guard outside the N6QW shack -- heck Mike even has an Arduino Uno and an Si5351 in there!  Don't do it Pete!

I was led to this magnificent receiver by the very humble 6U8 tube.  Scott  WA9WFA and I have been learning (mostly from Grayson KJ7UM) that the much used and sometimes loved 6U8s (three of them in our "Mates for the Mighty Midget")  might be a bit long in the tooth, old even by Thermatron standards.  I was worried when I remembered that my Drake 2-B has a 6U8 in it -- V2, the first mixer.   So I Googled for more info and was led to this amazing receiver, a 2018 creation by KG7TR.  How did we NOT see this for almost four years?

Here is more info and pictures: 

http://www.kg7tr.com/75s-2b-receiver.html

Here is Mike's write-up of the project: 

http://nebula.wsimg.com/c2281e9bdf3b54da42ca4b0b541b4ec9?AccessKeyId=D18ED10DA019A4588B7B&disposition=0&alloworigin=1

Mike KG7TR's web site:

http://www.kg7tr.com/ 

As for the 6U8s, well Grayson says the tube has been getting something of a bum rap.  And  KG7TR has two of them in this receiver, so I will obviously have to give the 6U8 another chance.  

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

I didn't know that Lew McCoy had his own crystal and crystal filter company: 

http://www.kg7tr.com/the-real-mccoy.html

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

Scott WA9WFA's Beautiful HBR-13 Receiver (3 videos)

This is Scott WA9WFA's first homebrew construction project.  He did an amazing job on a very complex project:  a 13 tube superhet receiver.  It features plug-in coils for multi-band coverage, dual conversion with IFs at 1600 kHz and 100 kHz, and several regenerative stages.  Scott's construction is top notch. He tells us that he had been working on this receiver for several years, so long in fact that some of his friends began to wonder if it really existed.  Well wonder no more.  Retirement has provided Scott with the time to finish this project. 

I like the way Scott talks about the project in these videos.  He puts it in the context of his long-standing goal of building his own high quality ham station.  With the HBR-13 done, he is more than halfway there.  We all know that the receiver is the hard part.   

I agree with those who say that Scott should keep the plexiglass front panel.  I think it looks very cool.  

In the third video, Scott takes us on a cruise through the 40 meter band.  The receiver sounds great.  Lou EA3JE's booming voice came through quite nicely from far-off Barcelona. 

Congratulations Scott on building a truly outstanding receiver. And on making some great videos. 

There is some additional background info on the HBR-13 in this blog post from back in September: 

https://soldersmoke.blogspot.com/2021/09/the-hbr-13c-homebrew-receiver.html

WA9WFA's Mate for the Mighty Midget 1966 QST Receiver

Scott WA9WFA and I have been exchanging e-mails about his Mate for the Mighty Midget receiver project.  This morning I finally took a look at Scott's we page on this effort.  There was a lot there that resonated.  For example: 

"I remember the moment very clearly.  June 1966 I was sitting in a lawn chair reading a stack of QST's that I had brought along to the summer cabin.  The February 1966 issue the Beginner and Novice section introduced the "Mighty Midget Transmitter", a 10 watt crystal controlled transmitter.  The April 1966 issue Beginner and Novice section introduced the "Mate for the Mighty Midget" which was a three tube super-heterodyne Novice type receiver.  Over the course of that summer I read and re-read those articles a jillion times.  Being 13 years old, I didn't have the electrical or mechanical skills to pull off such a project so I could only dream about it.  In 1970 I bought a handful of the parts.  In 1976 I bought more parts.  In 2021 I decided to build it while I still had the ability to do it.  This project is only my second homebrew radio project so I am still learning things every second of the way...

 

While I am not expecting to much in performance, the 13 year old in me is ever hopeful that this 1966 Novice receiver will be the most wonderful radio ever made.   73, Scott WA9WFA"

Scott's MMM RX page: 

https://www.qsl.net/wa9wfa/MateForTheMightyMidget.htm

Scott and I are now both updating the MMM RX by substituting 455 kHz ceramic filters for Lew McCoy's FT-241 crystal filter.   I have my filter wired in now, and it is working well.  Scott plans on soldering his in today.  I will post on this mod soon. 

On his QRZ.com page, Scott notes the need to fight the temptation to further soup-up this simple receiver:  "I did have to resist the temptation to add another audio stage, a mechanical filter, AGC, 2nd IF amplifer stage, etc..."

Exactly right Scott.  Resist the temptation.   Simplicity is a virtue.  I do use an outboard, powered computer speaker, but I justify this by telling myself that I just don't want to use headphones.  But I could use headphones, so this is OK.  OK?  

Scott's QRZ.com page: 

https://www.qrz.com/db/wa9wfa

I must add that I think the yearning of Scott's inner 13 year-old can be fulfilled by the MMM RX.  I think it is pretty wonderful.  It is -- in my view  -- not as good as a Drake 2-B, but it is FAR better than an S-38E, and it is better than a Lafayette HA-600A (wjm).  

No Longer On the "Shame Shelf" -- Pete Fixes His KWM-1

 

I think a good troubleshoot is almost as satisfying as a successful homebrew.  And we can sense that high level of satisfaction in Pete N6QW's description of his repair of a Collins KWM-1:   

http://n6qw.blogspot.com/2021/10/resurrection-of-kwm-1-sn-673.html

I liked Pete's troubleshoot/repair story, but -- as is often the case -- I struck by his turn of a phrase.  I think Pete has added something important to the SolderSmoke lexicon: 

THE SHAME SHELF 

Most of us have a shelf like this. I have an HW-101 on mine.  Pete shows us that there is hope -- there is path off of the shame shelf.  You just have to know stuff.... Or have IBEW friends like Pete who can advise you. 

SolderSmoke Podcast #233: PIMP, Boatanchors, Novices, MMM, Heathkits, DC Receivers, Mailbag

SolderSmoke Podcast #233 is available. 

http://soldersmoke.com/soldersmoke233.mp3

Travelogue: Cape Cod. SST. Marconi Site.

The WFSRA:   The World Friendship Society of Radio Amateurs.

Pete's Bench:

The Pimp.
The NCX rig.
The Collins.
The many DC receivers built worldwide.
The parts shortages are real! Several key radios on hold. Si5351 sub.
Talk to G-QRP convention

Bill's Bench:

FT-8. Not for me. I tried it.
Novice Station Rebuild.
Globe V-10 VFO Deluxe.
Selenium rectifier removal CONTROVERSY?
Not crazy about my Novice station. Not crazy about CW. 
Mate for the Mighty Midget. Again. 
Mike W6MAB -- Detector problems LTSPICE Check
One more mod for MMM RX. Ceramic filter at 455.
Dropped screw inside tubular cap on Millen 61455 transformer. 
Talk to the Vienna Wireless Society
Thinking of a Moxon or a Hex beam.


BOOK REVIEW Chuck Penson WA7ZZE New Heathkit Book. http://wa7zze.com

Mailbag

-- New SPRAT is out! Hooray!
-- Todd K7TFC sent me copy of Shopcraft as Soulcraft. FB.
-- Dean KK4DAS building an EI9GQ 16 W amp. FB.
-- Jack NG2E Getting close on Pete's DC receiver.
-- JF1OZL's website is BACK!
-- Tony K3DY sent link to cool books. 
-- Sheldon VK2XZS thinking of building a phasing receiver.
-- Peter VK2EMU has joined the WFSRA. FB!
-- Ned KH7JJ from Honolulu spotted the Sideband Myth in the AWA video.
-- Chris M0LGX looking at the ET-2, asks about the variometer.
-- Pete Eaton Nov 64 anti HB rant in november 1964 QST. Wow.
-- Josh Lambert Hurley spreading FMLA stickers in the UK. FB
-- Stephen VE6STA getting ready to melt solder.
-- Got a great picture of Rogier PA1ZZ back on Bonaire.
-- Farhan reading the manual of Hans's new digital rig.
-- Paul G0OER wonders if FMLA getting ready to move on 5 meters.

Scott WA9WFA's Mate for the Mighty Midget Receiver is WORKING! (Video)

Wow, Scott got his Mate for the Mighty Midget receiver to work and he is obviously overjoyed with the result.  All of us who have struggled with a homebrew project know just what this feels like.  And it is very cool that Scott got some useful guidance from Charlie Morris in far-off New Zealand.   Congratulations Scott.  I'm really glad you stuck with it.  

Scott's success comes at a good time:  Pete N6QW is building W4IMP's three tube "IMP" SSB transmitter (also from the 1960s).   I accept responsibility for naming Pete's project:  It will be known as "Pete's IMP" or, memorably,  "The PIMP."  For a look at Pete's rig go here: 

http://n6qw.blogspot.com/2021/09/lets-build-something-with-vacuum-tubes_23.html

Scott had problems getting Lew McCoy's 455 kc crystal filter to work.  So did I.  It turns out that this is a very old problem, going back to World War II.  In Don Stoner's 1959 "New Sideband Handbook" on page 54 he writes of homebrew filters in the 400 to 500 kc range:  

"Inexpensive crystal filters constructed from war surplus FT-241 type low frequency crystals are very popular with the 'do it yourself' hams. These CT cut crystals have been plentiful and relatively cheap for a number of years and are in the hands of many Amateurs. The general run of war surplus crystals may or may not be good. Experience has shown that one out of four of these crystals are usually defective in one way or another." 

Stoner was writing just 14 years after the war.  Add another six decades to the age of these crystals -- often decades spent in musty basements -- and you can imagine the percentage of bad 455 kc FT-241  crystals increasing.  So I think Scott is wise to seek an alternative to McCoy's crystal filter. 

Scott's original build of the MMMRX receiver is just so nice.   In the video he says he plans to go back to it after he gets the expanded version fully functional.  He should definitely do that -- his  original version looks so good.  I think it is probably very close to working properly. 

Thanks Scott, and again, congratulations OM.