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 Post subject: Heathkit HW-18
PostPosted: Nov Sun 06, 2011 8:49 pm 
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Not sure if this is the best place to post, but I thought I would take a chance here.

Yesterday, I picked up an old Heathkit HW-18 at a hamfest for $10. It is lacking a power supply, but seems to be an interesting beast!
From what I can tell, it is setup for MARS/CAP use as a 6 channel crystal controlled USB transceiver operating around 4450-4650 KHz.
It looks complete inside and has two VERY nice looking GE 6GE5 Compactron finals! They don't even look used. Must check them though.

The first thing I thought of is modify it for use on the channelized 60m ham band!

Has anyone ever done this?

-Steve


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 Post subject: Re: Heathkit HW-18
PostPosted: Nov Sun 06, 2011 11:27 pm 
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I agree that about the only practical use would be to retune it to the 60 Meter band, which is USB and channelized. Technically, it puts out too much power and doesn't meet the technical specs for that band (which are different than the rest of the ham bands) but it's not like anyone is going to notice or care.

The main thing that will kill this project, though, is the cost of crystals. At roughly $ 20 each from International Crystal, populating this radio with the 60 Meter channels gets expensive fast. The N3ZI DDS VFO kit gets around this, but even that is going to be $ 80+ for the full kit and you'll still need an enclosure and a buffer amplifier of some kind (such as a pair of PN2222's) to drive the Heath radio.

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 Post subject: Re: Heathkit HW-18
PostPosted: Nov Sun 06, 2011 11:54 pm 
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True, crystals will be the most cost prohibitive part of the project. As for the rest, I think it should manage to make the requirements which i find are:

US licensees operating 60m are limited to emissions of upper sideband suppressed carrier, 2.8 kHz bandwidth (2K80J3E), 50 watts PEP ERP relative to a 1/2 wave dipole.

ERP is Effective Radiated Power. The HW-18 is 200 watts Input which is significantly less output. Once you get losses on the coax and the fact that my antenna is a loaded vertical, I bet the resulting ERP will be around 50 watts. Plus, it probably isn't difficult to reduce its output power anyway :wink:

Whether or not I manage to modify this rig, I'm not sure. Like you said, the cost may just be too much!

Thanks for the comment! Still, I wonder if anyone else has actually done this?

-Steve

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 Post subject: Re: Heathkit HW-18
PostPosted: Nov Tue 08, 2011 7:08 am 
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Location: Long Beach Ms. Gulf Coast
I have two of these transcievers one of which I have modified and now use for a 600 meter exciter in my experimental station.
You should have very little trouble modifying yours for 60 meter SSB as long as you are willing to ask around for crystals. You will need a way to resonate the coils on the new frequencies.
Remember that they are reliable because they were built for CAP use with most operators not being repair-capable. Replace the usual suspects, especially the electrolytics in the audio section.
The Heatkit power supplies have two bias sources, full minus 130 and an adjustable bias, as well as two filament voltages. (The early supplies provided six and 12 volts AC for filaments) make sure of how your transciever was wired.

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 Post subject: Re: Heathkit HW-18
PostPosted: Nov Sat 12, 2011 1:36 am 
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I worked on one for Ohio CAP. Well I had several and managed to get one going good as I recall, before the project was shelved. They have moved on to better radios. In Ohio CAP they were disabling the clarifier controls so you best check to see if that is working correctly. I don't see why it can't be made into a perfectly serviceable radio but I cannot advise on retuning one to work off the 4.6 MHz. band, how easy that would be. Probably can use the same supplies as the other hot water radios from Heath. I have seen the monobanders for sale cheap and always thought of getting one for fun to mess with but no time to mess with it and no place to put in the shack anyway.


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 Post subject: Re: Heathkit HW-18
PostPosted: Dec Fri 02, 2011 12:00 am 
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Well, I just got news that the FCC has increased the maximum ERP limit on the 60m band to 100 Watts PEP which is probably well above what the HW18 can spit out through coax to a vertical antenna.

Anyhow, this project is put on hold anyway, and its a good thing as one of the channels has been moved. If I had ordered 5 crystals, one would have been made useless. :?

Oh well, in time... though right now my time is worth more that $$ to me...

-Steve
KA8RIZ

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