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Author Topic: HW101 QSK in CW (reciever slow to recover)  (Read 4997 times)
W0BTU
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« Reply #15 on: August 21, 2010, 09:10:00 AM »

... If, as I initially stated, carbon build up between RL2 pins 8 and 12 even though RL2 is not energize, it's possible residual ALC voltage may still be applied to some extent to V3 resulting in your receiver recovery problem. Therefore, try cleaning both relays. ...

About 30 years ago, I bought an SB-102, and if I recall, many circuits are very similar to the HW-101. I had the same problem.

It was owned by a heavy smoker. My problem was solved by cleaning the tobacco smoke residue off the circuit board in the right place. (Don't ask me where, it's been too many years.) That AGC circuit is extremely high impedance, and that dirt and residue was conductive enough to cause problems.

In discussing this fix with another ham, he told of some Heath circuit boards -- they were paper phenolic that turned darker brown with sustained ambient heat -- that had turned very dark brown and actually became conductive enough to cause the same problem as the smoke residue. The fix there was to take a small section of board out of the circuit.

I know it sounds strange, but it solved my problem. Hope it helps you.

73, Mike
www.w0btu.com
« Last Edit: August 21, 2010, 09:13:44 AM by Mike Waters » Logged

KE4JOY
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« Reply #16 on: August 21, 2010, 09:45:28 AM »

While were talking about cleaning relays and pcbs what are some good tips to accomplish these tasks?
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W0BTU
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« Reply #17 on: August 21, 2010, 10:38:53 AM »

While were talking about cleaning relays and pcbs what are some good tips to accomplish these tasks?

Q-tips and denatured alcohol for the PCB.

73, Mike
www.w0btu.com
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KE4JOY
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« Reply #18 on: August 21, 2010, 01:56:13 PM »

I would really like to hear some advice on cleaning the relay contacts.

I did a quick search on the site but came up with a bunch of "you should clean the contacts" but not to many 'how to'.
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W0BTU
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« Reply #19 on: August 21, 2010, 02:33:12 PM »

Do a Google search for "crocus cloth". It is the only thing you should clean relay contacts with.

73, Mike
www.w0btu.com
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KK7KZ
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« Reply #20 on: August 21, 2010, 03:15:22 PM »

I use a dollar bill with a little dab of alcohol on it to remove the grease; the fiber in the bill will burnish the contacts with 8-10 passes without damaging the surface of the contact.

-R.
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KE4JOY
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« Reply #21 on: August 24, 2010, 07:24:41 AM »

Well I took some time last night and cleaned the relay contacts and the topside of the IF pc board.

The board was coated in a greasy film which had collected considerable dust over the years. I'm assuming that someone had bathed the board in tuner cleaner  Undecided

After several hours with a bright light magnifying lenses and a pile of Q tips and alcohol I had at least the top of the IF board cleaned. I was amazed as just how dirty it actually was! Little pieces of oily lint... yuk.

I must have knocked something loose or changed the impedance enough to push the receiver over the edge now because it acts very erratic, motorboating, birdies, or just S9 of white noise. Then it will suddenly start working as it should.

I'm suspecting bad grounding and intend to loosen all the grounding screws around the perimeter of the board and trying to clean between the board and chassis with alcohol and a paint brush then tightening the screws.
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N0CGF
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« Reply #22 on: August 28, 2010, 02:34:07 PM »

I had this problem also with my HW-101.  After long transmissions on SSB or CW the recover time was very slow and the S-Meter would go up scale for a long time till receive recovered.  There was a Heathkit Service Bulletin listed on this to solve the problem.  This same Bulletin is listed on the www.oldheathkitparts.com website.  I installed this fix and it did correct the problem.  It just grounded the screen grids  of the 6146's during receive. To do this it just used free relay connections to ground the grids during receive. It does require wire adds and changes.   Also there was a fix that was published in the 1978 edition of the ARRL hints&kinks Book.  This fix was a very simple and yes,,  I forgot the details of it and I will look it up and respond back to this posting if someone else does not respond with it.    I do want to install this fix to my HW-101 when I do have the time,  and remove the fix that was in the Service Bulletin. The only reason for this is that the one listed in the Hints&Kinks  was a very simple wire add and delete to the HW-101.     N0CGF Dennis
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KE4JOY
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« Reply #23 on: August 29, 2010, 05:02:49 PM »

One step forward 3  steps back. I cleaned and reseated the modulator circuit board. Cleaned all those wafer switches on the bandpass boards while I was at it.

Got a good increase on microphone 'drive' but...

Now the receiver section is kind of dead with the AVC being very flaky. Here are the symptoms. Turn the rig on... meter pins for about 10 seconds or so then falls back towards zero but then upticks and eventually hangs out around S9. After a period of time the meter will fall back to S0 but incoming signals do not bounce the meter. Strong signals might twitch it a little.

Xmitter sections working fine, I tried tuning the IF coils and they centered right where they were.

Ive busted something and not sure what. I tried swapping around the IF amp tubes, I tried swapping out the RF amp tube. Same behaviour.
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KE4JOY
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« Reply #24 on: August 31, 2010, 08:50:38 AM »

Sorry to bump my own thread but some new developments.

I was able to solve the AVC issues in recieve which turned out to be the 14mhz coil slug slightly off and installing a more solid ground with jumpers from the PC Boards to solder lugs attached to the chassis. The reciever is now hot as a pistol and SSB transmission works good (albeit the audio drive is down again) with good signal reports from DX stations. But the  'slow to recover' after CW transmission has returned with a new twist.

Now even after a brief transmission of keyed CW the reciever seems to recover quickly however there is a strong S10+ noise that sounds alot like static crashes and static in general. The reciever remains in this noisy state untill I flip the mode button into 'tune' briefly and the reciever immediatly returns to 'normal'. I first suspected the relays I have had a chance to watch Relay 2? (the  one outside the RF cage) and its operating as it should. I will look into the other relay tonight but was wondering if anyone had a few hints here.
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