Oscillating Light Bulbs

Oh man, this is some fascinating stuff: old light bulbs found to be oscillating at VHF! Wayne, VA7AT, stumbled upon this phenomenon at age 13 while engaged in Knack activities. Now Joe Sousa explains the physics behind the emissions that caused Wayne's light bulb to interfere with the broadcast of baseball games. How long until AA1TJ has one of these bulbs on the air, making contacts? There is much in this that would appeal to Michael: light bulbs, weird physics, translations from German... You gotta love the BNC connector plugged directly into the bulb. Check it out the radio museum article here.

Hi Bill

There was a question posted on Antennex E-mail discussion group talking about how a vacuum type light bulb will oscillate and radiate RF at about 100MHZ. This answered the question I had since I was a boy of 13 experimenting with a light bulb in series with an electrolysis bath (aluminum electrodes with table salt dissolved in water) and 117vac. The bulb dimmed with the electrodes apart and at a certain position the radio I had on blanked out with fissing sound. I had to shut down the experiment quickly because the neighbors were listening on their favorite baseball game and cussed loudly .

I now know what happened on that fateful day. Here is a site I found about the oscillating light bulb http://www.radiomuseum.org/forum/rustika_lightbulb_fm_measurements.html

Wayne VA7AT

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Sputnik Rigs Cross the Pond, Cambridge to Cambridge

The Chief Designer, Michael, AA1TJ, alerted us to this wonderful post on Roger, G3XBM's blog:
http://g3xbm-qrp.blogspot.com/2011/09/sputnik-across-atlantic-today.html
We clearly see the spirit of the International Brotherhood of Electronic Wizards in Roger's comment: "Nice to think that valves used in missiles aimed at each other in the Cold War end in bringing friendship and joy. CW is a wonderful mode if you want simple equipment capable of DX." Indeed. Well done!

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Google, Supernovas... and DRAKES

I liked this ad for Google, but I now have the urge to decapitate my garden shed. Check out dad's Drake gear. Late in the clip you can see some beam antennas on a tower near the house.

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ALL the Bell System Tech Journals -- FREE!

Thanks to Dave, N8SBE, for alerting us to yet another tech treasure trove:

http://www.alcatel-lucent.com/bstj/

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Earthquake Video -- From Atop the Washington Monument

Check it out. This gives you an idea of what the August quake was like (albeit from a perhaps the scariest location):

http://youtu.be/BgHC2qREslw

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2-B Trouble Continues

Thanks for all the suggestions and encouragement. I agree with WA6ARA that the bandswitch is a likely suspect. For the E socket on the Drake 2-B (that's where my 22 MHz rock goes) the bandswitch switches in not just the crystal, but also a slug-tuned coil. It is presumed to be an overtone crystal.

The receiver works fine on all other bands.

I've already hit the wafer switch with several shots of RadioShack Contact Cleaner (I'm out of De-Ox-It). And I've given position E a good work out. No joy.

I will dig deeper this week.

It may be the crystal. It looks like I got it from Drake -- it is marked "22 MHz 2C" so it may be for the 2C receiver. It has a sort of worrisome dent in the side. I may build the test oscillator that Steve recommends.

Of course, as soon as I get this fixed the sunspots will disappear and 17 will become a white noise generator.

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2B Trouble!

So this morning I hear that the solar flux is up around 190 and the higher bands are coming back to life. I turn to my trusty Drake 2-B and turn the band switch from "40" (where it has been parked for quite some time) to "E." E is the position that kicks in the 22 MHz overtone crystal on the 6U8 local oscillator. I eagerly turn the pre-selector to the area where the 17 meter band used to appear and... nothing. Nada. Silence. No band noise. Nothing.

I thought the 6U8 might be going a bit soft. I swapped it out. The problem remains. I twisted that E band coil from one end to the other. Nothing. I cleaned the bandswitch contacts. No joy. Now I'm thinking it is the 22 MHz crystal. But its kind of strange for a crystal to just suddenly go bad... It worked before. The receiver is working on all the other bands, so the problem is really that the oscillator just won't go on 22 MHz.

What do you wizards recommend?

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Drake 2-B Video

Some cynical readers will see this as yet another effort on my part to drive up the net asset value of the SSDRA2B Investment Fund, but I really just thought that those of you who have not had the pleasure would enjoy seeing a Drake 2-B in operation. Pity he didn't have the Q-multiplier. I'm sure some of the other 2-B videos on YouTube (there are many!) will feature 2-B regeneration.


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HW-7s, CB:"A Gateway Drug", and The Manly Way to Tune a Transmitter

I got a kick out of this e-mail from Cory, WA3UVV:

Hi, Bill!

While listening to SS137, you brought back some warm memories.

Bert Sessler, WA3WAW and I both grew up in Uniontown and met via CB – which was a gateway drug to Ham Radio for many of us. Within a fairly short time, we became good friends. Although I moved away some 30 years ago, I always try to get together with him when I’m back in town.

The HW-7 references also reminded me of trips into the nearby hills (being a few years older, I had my driver’s license and car before him) with his HW-7 and some lantern batteries. We’d park my ’69 Chevy Nova and then hike the trails to find some suitable trees for antenna supports. Bert’s code speed was impressive right from the start and he’d work more stations than me, in rapid succession. (How many 25+ WPM Novices do you know?)

Later, I’d get a HW-7 (and TenTec Power Mite 2) for those hikes alone, but it wasn’t quite the same as doing it with a friend. These days, I go to parks in the relatively flat South Jersey or Delaware with a FT-817ND, MFJ-9030 or 20M VXO’d RockMite and TX Topper Amp. Recently, pangs of nostalgia for my HW-7 (and ARC-5 station, for that matter) have arisen. I know the receiver doesn’t stack up against the new stuff I have, but it was certainly good enough for many enjoyable contacts.

Also, John Zaruba, K2ZA, is a good friend of mine here in Gloucester County. I’ve laid hands on the DX-100 you now have. You should have seen the Collins A line John’s dad had in the racks. Everything looked almost factory new.

At our GCARC Hamfest over the weekend, John helped feed my tube addiction with 4 boxes of NOS tubes, shields, etc. I also bought his dad’s Meissner Signal Shifter. After giving it a respectful time to warm up and colorfully glow again (orange, purple and green from the “magic eye”), I attached it to a tungsten lamp – the “manly” way to tune a tube transmitter – and got RF! As it has a balanced 300 ohm output, I have to build a 6:1 balun and hope to have it on the air next week with its characteristic chirp. Hmm, just like the HW-7 and my ARC-5’s of years gone by…

I hope you and your family are enjoying life back in DC. It’s not the milieu of Italy, but at least you’re much closer to a Ham Radio Outlet!

All the best,

Cory – WA3UVV

PS - If you have a desire to home brew a 6L6 transmitter and need a tube, let me know. My mom taught me to share...

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Getting Ready to Listen for Sputniks

October 4 is approaching and I DO NOT have a homebrew Sputnik transmitter in the works. I hang my head in shame. AA1TJ sent me the parts, but they went to one of my many APO or FPO addresses, so I suspect they are orbiting around the Azores, or London, or Lisbon, or Rome. I'm sure they will reach me eventually.

But I have come up with a way to participate in this historic event even without a homebrew replica transmitter: I will be listening for the Sputnik transmitters, and I will be doing so with a receiver of that era, a receiver that could have been used by some earnest teenager eagerly tuning for the beeps of the overhead RED MENACE. Like the intrepid young man in the picture. What a great shot! Wow, that's Roy Welch W0SL, then W5SLL! When I got into satellites in the Dominican Republic in 1994, the first tracking program that we used was Orbits II... by Roy Welch. We loved that software. From the AMSAT page: "Roy and his two-year-old daughter would put the radio speaker in a window and then go outside and listen to the strong signals while they watched the third stage booster tumbling end over end like a bright pulsating star as it passed over in the evening sky."

I will be using a Hammarlund. Moore's "Communication Receivers" says my HQ-100 was made between 1956 and 1960. PERFECT! (Mine was probably in the Dominican Republic on October 4, 1957.)

By the way, I got into the old Electric Radio magazines again, reading some more of Lew McCoy's wonderful reminiscences. He reports that during the Sputnik period he -- and apparently others -- were asked by their Uncle Sam to use their skills to monitor Soviet space activities.

Let the beeping begin! (Sputnik signals recorded by Roy Welch:
http://www.amsat.org/amsat/features/sounds/Sputnk1b-144.ra)

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Mike, KL7R's HW-8 DSB Mod

The HW-8 rehab project of Ed, WA3WSJ, has led to a nice discussion on QRP-L about the possibility of using the HW-8 as a DSB rig. Mike, KL7R, did such a mod on his HW-8 many years ago and used it successfully in the field in Alaska. Read his story here:
http://kl7r.ham-radio.ch/hw8/hw8story.html

Nick, WA5BDU, and I have been discussing the possible need for an additional mod to put the HW-8's final in linear mode. The picture above is of Mike's rig, with the finals unbiased. Check out the scope. Looks pretty good to me!

Here's the e-mail exchange:

Re: [QRP-L] WA3WSJ Heathkit HW-8 Rebuild Status

Monday, September 19, 2011 7:32 AM

From:

"Nick-WA5BDU"

To:

"Bill Meara"

Cc:

qrp-l@mailman.qth.net, sigcom@juno.cm

I had the same thought regarding amplifier class, and Steve, WB6TNL also emailed the same observation.

The balanced modulator is inserted between the driver and final amplifier, which has no fixed bias and has its emitter grounded, so it's definitely class-C. I do note that the balanced modulator is passive and probably has 6dB or more of loss, so you're getting a pretty good drive reduction. And Mike said he adjusted the audio while watching the RF output until there was minimal flat topping on a scope. So I wonder if it's possible to keep things fairly linear if the power is kept quite low?

At any rate, I love the idea. Here's Mike in the 70s. He has an HW-8 he's familiar with, and he's reading SSDRA. Going over the simple DSB generation examples, he thinks -- why not stick this in the RF train of my HW-8?

72-

Nick, WA5BDU



On 9/19/2011 4:36 AM, Bill Meara wrote: Nick: I enjoyed reading about your HW-8 adventure, especially the part about Mike's work with this rig. I remember talking to him about it, and I've since come across some articles describing similar DSB mods. One thing that all of these plans lack, however, is a modification to the PA. It is Class C in the HW-8, and would need to be made linear for DSB service, correct? 73 Bill N2CQR

--- On Sun, 9/18/11, Nick-WA5BDU wrote:

From: Nick-WA5BDU
Subject: Re: [QRP-L] WA3WSJ Heathkit HW-8 Rebuild Status
To: qrp-l@mailman.qth.net
Date: Sunday, September 18, 2011, 9:44 PM

Sounds like a great project (or projects!) Ed.

I'm working on an HW-8 also. Bought it at a hamfest this Spring at a
good price, but suspected it might have some issues. When I started
playing with it I noted that transmit power was down, the loading
control was stuck, and there was no sound from the receiver.

The receiver issue was the most challenging and I eventually tracked it
to a leaky transistor in the T/R circuit which was activating the mute
function even when key up. I suspect that the transistor's problem may
have been due to the lack of a de-spiking diode on the T/R relay's coil
so I added one.

So far I'm not keen on modifying the rig and am even keeping the RCA
connector (spent an outrageous $5 for a RCA to BNC adapter from Radio
Shack). Well, maybe not outrageous, but I'm pretty cheap. Other than the
diode, I did add a 1A fuse and a reverse polarized diode downstream of
it for reverse-polarity protection.

After going thoThe HW-8 rehab project of Ed, WA3WSJ, has led to a nice discussion on QRP-L about the possibility of using the HW-8 as a DSB rig. Mike, KL7R, did a mod on his HW-8 many years ago and used it successfully in the field in Alaska. Read his story here:
http://kl7r.ham-radio.ch/hw8/hw8story.html

Nick, WA5BDU, and I have been discussing the possible need for an additional mod to put the HW-8's final in linear mode. The picture above is of Mike's rig, with the finals unbiased. Check out the scope. Looks pretty good to me!

Here's the e-mail exchange: ugh most of the alignment procedure (I don't have a tool
that will reach the bottom coils of the dual-coil adjustable inductors),
the VFO looks good and the power output seems about right.

It was nice that QRP Afield and the Washington Salmon Run were going
right after I did my repairs, so I was able to make ten or so QSOs to
try it out. It also reaffirmed the idea that QSOs can come pretty easily
at 1 or 2 watts out -- you don't need the full pentawatt. I had my first
QSO with the rig the night before, when it was fitting that I worked a
guy running a HW-101 who said he also had a HW-8. Heath to Heath at
random -- what are the odds?

I find that if I buy a used rig and have to work on it to get it going,
I develop a greater appreciation for it. If the repair is successful,
that is.
The HW-8 rehab project of Ed, WA3WSJ, has led to a nice discussion on QRP-L about the possibility of using the HW-8 as a DSB rig. Mike, KL7R, did a mod on his HW-8 many years ago and used it successfully in the field in Alaska. Read his story here:
http://kl7r.ham-radio.ch/hw8/hw8story.html

Nick, WA5BDU, and I have been discussing the possible need for an additional mod to put the HW-8's final in linear mode. The picture above is of Mike's rig, with the finals unbiased. Check out the scope. Looks pretty good to me!

Here's the e-mail exchange:
The HW-8 has an interesting mixture of modern and semi-vintage (70s)
features. Some things I found interesting were -

It uses a LM3900 quad Norton op-amp for the active audio filter, one
stage of audio amplifier, and the sidetone oscillator.

The final amplifier is a 2N4427 with a small heat sink. According to the
data sheet it is rated for 1W output at 175MHz and has GWB of 500MHz.(I
assume that's original -- I was sort of surprised it wasn't "house marked".)

It has a direct conversion receiver but has a heterodyne frequency
generation system. The product detector is an MC1496 balanced modulator IC.

The VFO tunes the same linear scale 250kHz on each band, 8.645MHz to
8.895MHz with a reduction drive. Pretty state of the art for the 70s.

Heath rates power the old way with power /input/ of 3.5, 3.0, 3.0 and
2.5 watts input from 80 through 15.

Bandswitching, covers 80, 40, 20, 15 meters.

The audio output stage is a small transistor in a common emitter
configuration with a 1kΩ resistor in the collector lead.So it can only
put out a small amount of AF power and into a high impedance (1k)
load.Has a mono ¼ inch phone jack and no speaker.

Keying is by pulling 12V to ground like in a modern transceiver.There’s
a keying offset of 750 Hz and you tune to the HIGH side to get on frequency.

Antenna switching is done by a relay with adjustable drop-out time for
semi-QSK.

Relative power output meter, not used on receive.


While doing web searches on the HW-8, I came across the web site of
Mike, KL7R (SK), late co-host of Solder Smoke.

http://kl7r.ham-radio.ch/hw8/hw8story.html

The idea that he put the HW-8 on DSB with such a simple mod really
impressed me. I think I'm going to fool with some DSB stuff in the
future, although I'm not sure I'll try it with the HW-8.

72,

Nick, WA5BDU


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The (much maligned) HW-7 Receiver

My HW-7 benefactor, Mike, WA3O, sent me some files related to this rig. Above, the original receiver. Very simple. Note the 40673 dual-gate MOSFET (often used by Doug DeMaw). The 40673 was implicated in quite a bit of square law detection of shortwave broadcast signals. I don't seem to be having much trouble with this -- could this be the result of the demise of many of the powerful SW broadcast stations? Perhaps the old, standard HW-7 receiver should be given another chance... As I type, I'm listening to 40 meters with this circuit and signals are just pouring in. It works just fine.

Here is one of the many mods recommended for the receiver in this rig. I like this one too -- those SBL-1 devices are very nice. They look like ICs, but they are REALLY simple and you can crack them open and see their innards.




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