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Author Topic: HW-101 bandwidth/audio  (Read 2873 times)
KI4DTB
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« on: January 18, 2012, 07:07:21 AM »

Hi everyone.  Recently acquired an hw-101 and tried out yesterday.  Am having trouble with the recieve tuning/audio.  Both rf and af gain controls have lots of gain, but it requires very very fine tuning to hear clear intelegible speach.  Often if one station is even slightly off freq. it will not be clear.  Is this normal for the 2100khz filter in the rig, or do I have a problem?  Is there a heath or hw-101 forum anywhere, where owners can compare notes?  Thanks for your help and 73.  Doug KI4DTB.  PS recieve seems to work best when rf and af gain are turned down.
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G3RZP
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« Reply #1 on: January 18, 2012, 07:29:16 AM »

Is the S meter working - indicative of the AGC being OK? from memory, the AGC wasn't that good. The filter in mine is about 1.9kHz at -6dB, with a good 4 or 5 dB of ripple, so the audio on both transmit and receive is pretty crap.. Regrettably, International Radio are out of stock of  3395 2.3 kHz or so filters, and are unlikely to get any more - I guess there's little demand these days.

The HW101 was OK in its day (despite what AC5UP may say!) for what it was. The dial drive is better than the HW100, but not a lot. It really does need IRT.
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N4NYY
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« Reply #2 on: January 18, 2012, 10:33:34 AM »

Quote
HazardousWaste-101

LOL ! 


That is just wrong!
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N4NYY
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« Reply #3 on: January 18, 2012, 10:40:27 AM »

Here is a list of HW-101 service bulletins: http://www.ultrawebb.com/OHP/SERVICE.htm

JUNE 5, 1978

HW-101 BULLETIN NO:

SSB TRANSCEIVER HW-101-24

 

POOR AGC ACTION

Leakage in the 6HS6 tubes [PN 411-247] at V10 and/or V11 has been found to cause:

- poor AGC action

- Fast S-meter decay

- poor sensitivity when RF gain control is fully clockwise.

This usually occurs after warmup of at least an hour. A positive voltage, usually over 1 volt, will appear at the grid, pin 1, of either one or both tubes.

 

Replacement of the tube with the positive voltage corrects the problem.
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AD4U
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« Reply #4 on: January 18, 2012, 11:38:35 AM »

As a restorer and as a user of old gear, I can positivily say that the 2.1 KHz 6 pole SSB crystal filters in the Heathkit SB and the 2.1 KHz mechanical SSB filters used in the Collins S line definitely sound a bit more "tinny" than the modern 2.4 KHz or 2.8 KHz filters.

The very first thing I always do when I start restoring any Heathkit is to go STEP BY STEP through the building process in the manual.  It is amazing how many construction errors and / or poor solder joints I have found.  Many of these errors did not keep the rig from working, but they kept the rig from working properly.

Clean all pots, tube sockets, and tube pins with a GOOD contact cleaner.  While the tube socket is still wet with cleaner, reinsert the tube and wiggle it around a bit.

When you finish this, if everything was originally put in its proper place, as in any 35-40 year old rig, there could be MANY problems that could cause the audio to be more "tinny" than normal.  

Components (resistors and capacitors) that have aged and drifted way out of tolerance.  Let me stop right here.  I recently finished restoring a Heathkit SB 102 transceiver than had 37 resistors that had drifted WAY out of tolerance and that had to be replaced.

"Bad" crystal filter.  It happens!

Construction errors.

Defective tube(s)

USB and / or LSB carrier oscillator crystal(s) that have drifted off frequency.  In the Heath gear there is no trimmer capacitor on these crystals as in many other rigs.

As far as the AF and RF gain controls being very "touchy", that (IMO) is not normal.  You may want to start looking for the cause of this problem in the AGC chain.

Good Luck

Dick  AD4U


« Last Edit: January 18, 2012, 12:15:26 PM by AD4U » Logged
WB6RXG
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« Reply #5 on: January 18, 2012, 03:02:31 PM »

One of the crystals could be off frequency and properly tuned audio is bumping into the skirts of the filter.

73,
Stuart
WB6RXG
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PBPP
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« Reply #6 on: January 18, 2012, 04:43:51 PM »

Nelson / AC5UP

Whazzamatta with Heathkits?  Too many moving parts for you to build properly?

LoL!
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AC5UP
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« Reply #7 on: January 18, 2012, 04:49:52 PM »

How would I know? Never could figure out how to get the box open...........
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Never change a password on a Friday                
KB4QAA
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« Reply #8 on: January 18, 2012, 05:46:59 PM »

It's probably rusted shut.  Smiley
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KI4DTB
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« Reply #9 on: January 19, 2012, 05:38:08 AM »

Thank you all for your input.  The information was very helpful, and I even enjoyed the (humor?).  Sounds like I have plenty of things to play with, starting with tubes and agc.  But that's the fun of haming.  Poor quality or not, it's great to hear the bands sound like they did when I was a novice.  73 And thanks again to you all.  Doug
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