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Author Topic: Heathkit HW-100 Allignment Problem  (Read 2451 times)
N0NS
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Posts: 45




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« on: January 16, 2008, 07:04:36 AM »

Hi everyone,

A friend lent me a Heathkit HW-100 and so far I have made about 50 contacts on 40 and 20 CW.  

The radio puts out a solid 75-100 watts on the 40 meter CW band above 7.025 Mhz and the entire 20 meter CW band.  

When I tune below 7.025, the power drops down to 10-25 watts.  On the 80 meter band, I get about 10 watts out.

I have noticed on the 40 meter band near 7.025Mhz, the Driver/Preselector knob is turned all the way to the left edge of the stop which tells me that something is not properly alligned.

I have the Heathkit manual for this radio but the allignment procedures seems rather cryptic to me.  I only have a multi-meter at home for test equipment.

So, any ideas on how to rectify this situation so I can get in the DX window of 40meters and on 80meters?

Thanks!  Joe N0NS
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KA5N
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Posts: 4380




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« Reply #1 on: January 16, 2008, 08:23:13 AM »

The SB-100,101,102 and HW-100 and HW-101 all have similar circuits and are a bit tricky to align.  While I wouldn't call the instructions "cryptic", they must be followed in the order given or you will wind up with a non-aligned transceiver.  The driver grid and plate alignment is the most likely culprit in your problem.  Since the coils are progressively shorted out as you go higher in frequency, the 10 meter coils are used on all bands (except 80) and are tuned first, then the 15 meter coils, then the 20 and then the 40 coils.  When in 80 meters the 10-40 coils are switched out of the circuit and 80 meter tuning is not dependent on the tuning of the other coils.
So the problem on 40 meters can be caused by misadjustment of any or all of the 10,15,and 20 meter coils.  
My suggestion, since the rig works pretty well for the most part, is to go to the driver grid and plate alignment section.  Using a correct type hex plastic tuning tool (don't use a metal tool as that affects the tuning, and an incorrect tool may crack and ruin the tuning slug) tune first the 3.5 coil (80 meters) and procede through the rest of the coils in the order given.  When done correctly you should be able to get the correct amount of power out on all bands.  You will usually get a bit more on 80 and 40 than the higher bands.  If this doesn't work get local help from an experienced ham.
Good Luck
Allen
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N0NS
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Posts: 45




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« Reply #2 on: January 18, 2008, 08:10:29 AM »

Allen,

Thanks for your advice.  You gave me the motivation to re-read the HW-100 schematics and the courage to tweak on the rig again.  It was in fact the grid and plate coils and in about three minutes, I brought back the missing power on the low end of 40 and all of 80!  Yay!

Joe N0NS
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KA5N
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Posts: 4380




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« Reply #3 on: January 19, 2008, 11:55:35 AM »

Once in awhile I luck on to the correct approach.
Happy DX
Allen
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KL7AJ
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Posts: 340


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« Reply #4 on: February 16, 2008, 02:40:22 PM »

I bet your receive sensitivity drops off precipitously at the same frequency.  There is a slug in there the probably needs tweaking.  You should find a peak on-scale.

eric
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