Posts Tagged ‘Heathkit’
Awhile back when I assembled the Amateur Radio Kit Roundup, I listed Heathkit as a potential source, and even answered a question in the comments about their rumored return to Amateur Radio stating that I would contact someone about it. I sent an email off asking how they were doing in this regard. Unfortunately I never received an answer. Here is some sad news at the ARRL explaining why (courtesy of a mention at eHam.net this morning). I was not a ham when Heathkit was in its heyday, but knew plenty of people who were, and like most of you, I was impatiently awaiting news of their return to the hobby. Hopefully this is not a permanent end, but only a temporary setback.
Work has been conspiring to eliminate my spare time but I was able to spend a few hours over the Easter holiday to clean up the shack and make space to put the Heathkit AT-1 on the desk again. I have been able to spend a little time going over parts that need to be replaced and making a list.
|The Heathkit AT-1 chassis with case and VFO-1 behind.|
There doesn’t seem to be any show stoppers although the wafer of the meter switch has broken in two and will need to be repaired. If I’m not able to repair it then thankfully it is fairly simple and replacement rotary switch can be substituted.
This isn’t going to be a museum quality restoration but the changes that were made to this transmitter in the past were sensible and if left in place are representative of period modifications. The original meter for example was not the highest quality and a Western or Simpson replacement would be an improvement. The original slide switches have been replaced with period snap-toggle switches which are also an improvement over the original.
The Heathkit VFO-1 however has been modified for grid-block keying which is a significant departure from the original and I plan to revert it back to cathode keying. Although a technical improvement it is not in keeping with the original design and needs to be undone. Everyone will have their own opinion but I think if I wanted modern circuits I’d get a more modern rig, so the VFO-1 will be returned to stock.
Hopefully I can carve out a bit of time here and there to work on this and slowly return it to working condition.
The Heathkit AT-1 represents the commercial embodiment of the simple Master Oscillator Power Amplifier (MOPA) transmitter using a crystal controlled 6AG7 oscillator plus a 6L6 final output tube.
Although it was possible to design and build a simpler transmitter, the goals of output power and stability could become mutually exclusive when trying to operate with only one tube. For a novice class license holder of 1951 the Heathkit AT-1 represented a solid performing rig that would be relatively easy to construct and operate.
The Novice remained the primary entry license until the Morse code requirement was eliminated for Technician licenses in 1990. On HF it permitted code transmissions only, with a maximum power of 75 watts, (input to the transmitter’s final amplifier stage) on limited segments of the 80, 40 and 15 meter bands.
|For $29.50 and the loan of a few tools you could get some use out of that new novice license|
The earlier MOPA circuit from the ARRL handbook of 1941 below shows a layout remarkably similar to the circuit of the AT-1 although it is designed for plug in coils rather than the band-switching arrangement of the later Heathkit transmitter.
|MOPA transmitter using a 6L6 and an 807 as the power amplifier (ARRL Handbook 1941)|
For a little added complexity MOPA transmitters generally offered better stability of frequency and keying waveform than single tube crystal controlled or self exited rigs. The straight forward design of the AT-1 should have looked familiar to novice class hams after studying the ARRL handbook or other radio publications.
|Heathkit AT-1 Circuit diagram showing band-switching arrangement and link coupled output|
Once the novice had upgraded his license the AT-1 could be expanded by the addition of the Heathkit VF-1 variable frequency oscillator to allow transmission on any frequency within the allowed band.
|The Heathkit VF-1 Variable Frequency Oscillator|
The VF-1 covered 160-80-40-20-15-11-10 meters and used an OA2 voltage regulator tube to provide a stable voltage for the oscillator. Ceramic coil forms, solid construction and high quality components were used to help increase stability.
|The Heathkit AC-1 Antenna Coupler. Designed to attach to a single wire by the insulated post on the front panel.|
|Heathkit AC-1 Antenna Coupler circuit diagram|
Although Heathkit did not produce a AM modulator for the AC-1 there is provision for modulator connection on the rear panel. The earlier ARRL manuals have several suitable circuits for modulators that would work with the AC-1. Most functioned by driving a modulation transformer with the output from an audio power amplifier. The secondary of the modulation transformer would be carrying the DC plate supply for the power amplifier tube plus or minus the instantaneous voltage of the audio waveform. By changing the plate voltage to the final amplifier tube the radio frequency output would be controlled by the amplified audio frequency resulting in amplitude modulation.
I’ve been seeing on the googles and the twitters, that HeathKit is going to start selling kits again, but not for Ham Radio. They are going to start selling “Do It Yourself Kits” for around the house. While this is great, It’s kind of useless for me.
The first two kits they are offering is a garage parking assistant and a wireless swimming pool monitor. I’m sure these will be great kits and lots of fun to build for many people out there, but not for me. You see, I live in an apartment. Curses, foiled again! But in seriousness, with Heathkit’s come back, it kind of makes me wonder why now? I’m guessing the economy is not what it used to be and money is getting a little tighter. So they are just firing up an old revenue stream that has been dormant a long time and getting back to what worked?
I have never built from a kit, but I have owned kit made electronics before, buying them after the person who made them, then got tired of them. I used to own a nice Heathkit AM/SSB HF transceiver back in the early days of my license. I think it was around the time I upgraded to General Class. While they haven’t started offering anything Ham Radio related yet, they are looking for suggestions for new projects. A couple that come to mind for me would be, an APRS kit and maybe a small CW or SSB transceiver for backpacking or mobile use. That would have to be pretty rugged though, so not sure how that would play out.
But with Radio Shack also getting back into the DIY arena too, things are starting to come full circle and we’ll have a new generation of kids able to build some pretty cool things on the weekends, keeping them off the interwebs thingy and the facebook doo-dads. Maybe even a return to the catalogs we would get every now and again, and would eagerly await in the mail, like I used to wait for the Sears and Montgomery Wards catalogs for Christmas to see all the toys. But being the 21st century, the catalogs would be in PDF format, and delivered by email.
Last week at the Waverley Amateur Radio Society monthly meeting there was a fascinating and well-prepared talk from Justin Lavery VK2CU on the history of the Heathkit company.
The scene at the front of the clubroom was not unlike this great shot from the website of Fred W1SKU.
Only there were more pieces of equipment on display! Justin’s clearly been collecting for a while, specialising in valve gear and the SB series. He had a stash of catalogues dating back to the early 1960s which evoked memories for many of us there old enough for Heathkit – even on the other side of the Pacific Ocean – to have been a radio icon.
Justin filled in the deep history of the company, with its kit airplane beginnings through to its heyday when it actually made economic sense to build your own colour TV!
He also managed to evoke the history of the time – which is some achievement for someone who I don’t think was actually alive for most of it!
MAKE magazine beautifully evokes the times and the anticipation – those long painful delicious moments between posting the order and the kit arriving.
I was especially interested in observations about how the fortunes of the company were in synch with a strong tradition of making it yourself – which seems to be a core part of both the US and Australia. We both have frontier experiences still in our recent folk memory.
I wonder what Heathkit would make of the kit market today if they were still around. They certainly set a benchmark. And they certainly sold a lot of kits over the years.
So it was an interesting coincidence for me at least that on the same day as I’m thinking about Heathkit and how I used to long to own an HR-10 and a DX-60, I received my Genesis G59 Mk2 SDR transceiver kit.
The Genesis G59 is a very exciting sounding project. I believe I’ll have a pretty impressive SDR transceiver once it’s complete.
While GenesisRadio is more cottage industry in scale than Heath – who grew so much they opened a factory in the UK – the quality is there where it counts. Part of the decision to take the plunge was an estimation of the support both from Nick Hacko VK2DX and the online community of builders on the Yahoogroup.
The then and now comparison shows how much kit building has changed. Kits now can be delivered across the world in days. Speedy support from a global network of enthusiasts is available via email. Documentation is able to be kept up-to-date and builders alerted to important developments. And most amazing, of course, the firmware can easily be updated and improved.
The key to the success of all of this is the social glue of the builders online. That’s another reason not to delay the build and to glean maximum advantage of the communal energy available there.
The Genesis documentation is clear with excellent photos. Not the component by component style of Heathkit, but totally adequate.
So far I’ve completed phase 1 successfully (the power supply) and am in the middle of the second phase (the microcontroller circuit). I’m taking it slowly and really enjoying those moments at the end of the night when I can get to it. That lateness is the one reason I’m taking it slow. The other is – I really enjoy this part!