by Kevin Strom, WB4AIO

HERE’S an mp3 of Paul, WA3VJB the other day on 7290 kHz as heard on my Racal RA6790/GM in its widest — 20 kHz — bandwidth.

Although my urban Charlottesville location adds some noise and my receive-only antenna is far from optimal, Paul’s Collins 300G still impresses with its round, dense, satisfying sound. It’s not often I get to use the 20 kHz filter. And it is great to hear a transmitter that I worked on many years ago (when it emitted 1 MHz waves instead of 7 MHz ones) on the air again and sounding better than ever.

And here’s another recent 7290 recording — this one of Joe, W3GMS.

Although a local plasma TV created some interference, the fantastic down-to-almost-DC frequency response of Joe’s rig (that makes any speaker sound better than an original Advent) comes through great in the Racal’s 20 kHz position.

The Racal’s synchrodyne AM detector is very interesting and reasonably high fidelity (as long as the AM station being received does not hit the 100% modulation baseline). I have modified the audio and AGC circuits in the Racal for better audio quality; they are a work in progress.

A scan of Harvey's signature from one of his many "care packages"

by Kevin Strom, WB4AIO

THANKS to Mike, ex-N3GVA, some precious audio files were recently rescued, and we once again have access to the recordings of W8MPB, Harvey Heinz, made during his final days with us in March, 1999. We also get to hear KE2LO, W9OAG, N8ECR and other voices which we sorely miss on 3950 these days.

W8MPB Returns - Initial Test (March 1999)
W8MPB Returns - Harvey Himself (March 1999)
W8MPB Returns - Harvey Himself 2 (March 1999)
W8MPB Returns - Scott is Home (March 1999)
W8MPB Returns - Scott's Reward (March 1999)

One of the humorous graphics created by Harvey Heinz, W8MPB. His mailings also included copies of rare books and texts, spiced with technical information and original cartoons mocking the jammers and would-be censors of 75 meters.

Harvey Heinz (who also held the call sign N8TFB for a number of years) was a well-known regular on 3950 kHz and the Liberty Net.

His “info-pack” mailings of articles, original cartoons, and inside information from his P.O. Box in Gladwin, Michigan were frequent and welcome visitors to our mailboxes. These “care packages” contained reams of printed materials and, in later years, diskettes containing text files, graphics, schematics, and sometimes even entire books. Harvey was the creator of the N8TFB Trap Dipole, which was used with success by quite a few stations in the 80s and 90s.

When these recordings were made, Harvey had cancer and had just suffered a severe attack of pneumonia from which he never recovered. He had to go on oxygen and was unable to repair or maintain his station. Not only was he sick, but he was off the air and cut off from his friends.

Thanks to the hard work and kind heart of Scott, WB8RAV, Harvey got back on the air for a time just before the end. These recordings document his comeback and Scott’s mission.

Harvey Heinz worked for Collins Radio when it still was Collins Radio. According to a friend, “I don’t know if you know this, but Harvey worked for years for Collins Radio Company. He worked all over the world for them, and is quite the practical RF engineer.  I met Harvey years ago on Liberty Net.  We used to converse quite a bit, and he told me the story of how when Rockwell was taking over Collins, how all the Hebrews wearing yarmulkes were going through the plants and books, and snooping around.  They didn’t try to hide it.  Then and there Harvey decided to retire from Collins/Rockwell.  Just at that time all the Collins gear went downhill and has never come back as far as I know.”

Most of the 3950 regulars received Harvey’s frequent mailings. One wrote to me, expressing hope that Harvey could some day get on the Web: “Yep, you are right; if I want to send any pictures to Harvey I have to mail him a disk.  He’s not on the Internet yet, but he tells me there is a provider in Gladwin.  He just needs a push to get him online. I don’t think he realizes all the ‘damage’ he could do by having full access to the Internet.  Boy, if ever there was a fellow who should be on the Web, it’s Harvey.”

One week after W8MPB returned to the air, we received this email from the late KE2LO, Gene:

“I have just been informed by Harvey’s brother that Harvey passed away last night. He awoke briefly to hold his wife’s hand and say goodbye, then gently passed.

“This is a sad day for me and all of you. As a friend of Harvey’s I will miss this pillar of principle and the wisdom he afforded to all.  I will miss the friendly phone calls and the care packages that Harvey sent to all of us.

“For you who never had the fortune of talking to or knowing W8MPB, I am sorry; you would have liked him and he would have appreciated you.

“Harvey’s brother Russell said Harvey left him instructions that if he passed, he was to call me and I would inform all of his friends on 3950 that he says goodbye and 73.

“Special thanks to everyone who helped or offered to help make Harvey’s last days with us as comforting as possible.

“A very special thanks to Scott (WB8RAV), Craig (N8SFY), and the ham in Gladwin — Scott Wolfing — that Craig contacted to help Scott get Harvey back on the air for the last time.

“73, Gene (KE2LO)”

The voice is now silent, but the radio waves continue to travel through the cosmos, and the wisdom is passed on to new generations of our people.

I don't know if you know this, but Harvey worked for years for Collins
Radio Company, he worked all over the world for them, and is quite
the practical RF Engineer.  I met Harvey years ago on Liberty Net.  We
used to converse quite a bit, and he told me the story of how when
Rockwell was taking over Collins, how all the Hebrews wearing
yarmulkes were going through the plants and books, and snooping
around.  They didn't try to hide it.  Then and there Harvey decided to
retire from Collins/Rockwell.  Just at that time all the Collins gear went
downhill and has never come back as far as I know.

by Kevin Strom, WB4AIO

THANKS TO an anonymous listener and the Audio Vault at amfone.net, we now have a audio clip of my AM station, recorded while I was living in Rochester, Minnesota in 1996.

At the time I was running my highly modified Kenwood TS-440s on 75 meters into an Alpha 77D at about 300 Watts into a 150′ inverted L antenna that just barely fit into my small city lot. (All that gear is now gone — stolen from me along with nearly everything else I owned.)

The signal isn’t bad considering that it was presumably heard a thousand miles away on the East Coast. You can hear the recordist adjusting the bandwidth (sounds much better in the wide mode) during the segment. I’m discoursing on ‘AM-ology,’ a field which certainly deserves further study!

by Kevin Strom, WB4AIO

I’VE JUST DISCOVERED a new and worthwhile amateur radio net, meeting Saturday mornings on or around 3872 kHz in the AM mode. It’s the Flex Radio Users Net, devoted to discussions of the software-defined transceivers manufactured by Flex Radio Systems and related topics.

This week, the group was discussing both the theoretical and practical aspects of symmetrical versus asymmetrical modulation, modulation levels generally, and audio processing for HF amplitude  modulation transmission.

The discussions included insights and opinions — and quite a bit of debate and disagreement — from AB2EZ, WB2CAU, N3WWL, N2DTS, and others.

Ever since I was the chief engineer at WEAM in Arlington, Virginia, this has been a topic of great interest to me. The 1970s and 1980s incarnation of WEAM used a 10-kilowatt RCA BTA10U2 plate-modulated transmitter with reduced B+ voltage on the final amplifier running just 5 kW output. It was capable of cleanly modulating more than 170% in the positive direction. Extensive experimentation has led me to agree with Mike Dorrough (KO6NM) on asymmetric diode-detected AM, particularly when skywave is a factor:  It is better to reduce voice asymmetry with all-pass filters and stay close to balanced positive and negative peaks in audio processing. This eliminates the inherent distortion caused by forcing positive peaks to be higher, and also causes the character of any limiter-induced distortion to be more “musical” and pleasing to the ear. It also minimizes selective fading distortion and distortion caused by detector nonlinearities at modulation extremes. And any dB or two “loudness deficit” compared to aggressively induced or natural asymmetry can easily be made up in the adjustment of the final limiter. (By the way, Inovonics is now producing broadcast audio limiters designed to force symmetry in the final audio waveform, in total contrast to the forced asymmetry that has been the prevailing paradigm up ’til now. )

You can listen to a big excerpt from the Flex Radio Users Net here, as recorded by me from an online Icom PCR-1500:

The TEAC A-3340S, the model which was the main WB4AIO recording deck for many years, before it was stolen (along with virtually everything else I owned) in 2006. Today I use Cool Edit Pro (a PC-based audio suite) to make most of my recordings.

by Kevin Strom, WB4AIO

I’VE JUST added two sections to 3950.net, one appearing in each sidebar, showcasing some interesting amateur radio audio recordings. Make sure that javascript is enabled in your browser for this site, and you’ll see a list of recordings with a small arrow on the left of each listing. Click on the title or the arrow, and a small player will open up, allowing nearly instant playback of the file. Click anywhere on the progress bar to skip around, and right-click the ‘download’ link which appears during streaming if you want to save the file to your hard drive.

The ‘Recent Recordings’ section will offer recordings of QSOs or other interesting audio that I come across, and the ‘Liberty Net Audio’ section will feature, with the help of N2IRJ and his high-quality noise-cancelling antenna system and highly-modified receivers, recordings of the Liberty Net current events discussions that are on the air every Saturday night. (At the moment, there’s just one partial recording of a Liberty Net session posted, and that was recorded on a conventional receiver.)

Among ‘Recent Recordings,’ I’ve posted transmissions from W3GMS and W1AEX which show off their excellent AM audio:

And I’ve also showcased a discussion between WB2CAU and WA1HLR on the former 75 meter spy numbers station apparently operated by an Eastern Bloc intelligence agency, and WA1HLR’s marathon transmission describing his adventures running an underground cable for his AC power backup system:

WA1HLR/WB2CAU discuss 75 meter numbers station
Enjoy!

Kevin, WB4AIO.