Friday, January 24, 2014

The Hot Water 7, first contact!!!!

I picked up a new "old" radio from a friend, W0RW, Paul of HF Pack Fame. I was looking for a HW-8 or HW-7 and after a few unsuccessful bids on ebay I was able to purchase Paul's.

Heathkit HW-7 circa 1973
I did some minor modifications to it and still have a few more to do. Overall I am pleased as it is fun to work on. I have not been able to get a keyer to work with it (HD-1410 and a Cricket 1). I performed the modification in order for it to work with a modern keyed but so far no joy. I used my Dad's straight key with it today as that seemed appropriate.  I added a few LEDs (green ones, after all it is a heathkit) and and just built an Elecraft AF-1 for audio filtering to use with it.

Green LED Glow
I think this speaker is a good match for the little HW-7
The Elecraft AF-1 really works well in the shack but not suited for portable work
Today was the first time I had it on the air. I worked my friend John, N0EVH in MO and Dan K6CAB/5 in TX with about .5 watts on 20 meters using a ground mounted vertical.

I really need to do that following things.
1. Get a keyer to work
2. Replace the clunky TR relay (I wonder if that would solve number 1)
3. Add a RIT as there is no offset
4. Add an INTERNAL audio filter and amp
5. Get rid of the power supply hum

It was a real thrill to use the radio today. My plan is to take it out to a SOTA summit and do a vintage SOTA activation. Of course I plan to use it in the shack from time to time as well and am looking forward to putting it on the air for the ARRL 2015 Straight Key Night.

72
Frank
K0JQZ

3 comments:

  1. Frank,
    Saw you in the HW-8 yahoo group. I also have a blog here at
    kc5ilr.blogspot.com Anyway I have an HW-8 that works awesome, and an HW-7 that I'm still tinkering with. It is SO exciting to make a contact with these little rascals isn't it? Love the green LED's!
    Pappy
    KC5ILR

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  2. Almost forgot... I think I learned it fromthe yahoo group, but if you move the power supply about 3 feet from the radio, the hum will cease. Worked great on mine. Maybe you could try it.
    Pappy
    KC5ILR

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  3. Frank,

    I also acquired a HW-7 from Ebay. "Guaranteed not work" read the listing.
    Re: Audio filter, I bought the Hi Per Mite 700 Hz filter+audio amp board.
    See: http://www.accuweather.com/en/us/tacoma-wa/98402/daily-weather-forecast/331423?day=6
    I haven't installed it yet, but I did a bench test and it works very well. I plan to simply sub the Hi Per Mite for the old school Audio IC in the HW7.

    I found a few RIT mods and compiled them into that works well for me. The trick is to get 700 Hz offset correct on each band. Shifting 700 Hz on 40 makes it way off at 15 meters. I used spare switch contacts in the Push Button band switch to switch in different resistor values for each band. Plus I had to drill a hole in the F panel for a small pot. I dont have any documentation on this yet... maybe I can hurry up and do that.

    Lastly I am experimenting with a SBL-1 mixer, which will remove the hum and unwanted local and shortwave BC stations. This effort is my biggest hurdle. I have made contacts with my HW7 and it is a lot of fun. 72s
    Rich KR7W
    W7W/RS-xxx

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