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Author Topic: HQ-170A -- The Trouble With Tubes, Experts Wanted  (Read 4611 times)
K7PEH
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Posts: 1124




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« Reply #15 on: February 23, 2012, 08:13:26 PM »

Allen,

OK, I think you might have my problem confused with someone else's problem or maybe someone else's comment.  My question was all about the "reason" for a tube substitution.  I didn't understand why it was done.  I will not go into the same explanation but you can clearly re-read it here at the start of this thread.  So, I am at a loss to what "other" problem you might be referring to that might be fixed by capacitor replacement or other similar changes.

So, my guess is that you might have read something into this thread of messages that I never put there.  I was not complaining about some problem, I was asking about why such a tube would be replaced.  I was asking if anyone knew why such a thing would be done.  And, one person did know.  He referred to a similar kind of tube substitution due to lacking access to the original tube.  This lead me to finally finding the time to open up the cabinet underneath and then examining the work that had been done and the re-wiring and so on.  Thus, mystery solved for the most part.
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KA5N
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Posts: 4380




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« Reply #16 on: February 24, 2012, 03:05:43 AM »

Dear K7PEH   
My comments about capacitors was directed to KE9UA who posted his audio problems
on this thread. 
I am only confused by the fact that you assume that any post is directed directly to you
and only you.
If my posts (which are intended to be helpful) offend you then just ignore them.

Allen C. Ward  KA5N   formerly W5FIP, and WN5FIP   (been a ham for 57 years)
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K7PEH
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Posts: 1124




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« Reply #17 on: February 24, 2012, 07:03:01 AM »

Dear K7PEH   
My comments about capacitors was directed to KE9UA who posted his audio problems
on this thread. 
I am only confused by the fact that you assume that any post is directed directly to you
and only you.
If my posts (which are intended to be helpful) offend you then just ignore them.

Allen C. Ward  KA5N   formerly W5FIP, and WN5FIP   (been a ham for 57 years)

OK.  But, it is confusing.  If your post is directed to someone in particular other then the original
posted question then you should direct it to that person.  That lessens the confusion.

They didn't offend me, they merely caused curiosity.  A puzzle so to speak that I needed
an answer to.  I mean, an answer to "why" you said what you said since it was
seemingly confusing to me.
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WA2CWA
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Posts: 296


WWW

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« Reply #18 on: February 25, 2012, 12:26:19 AM »

This thread is starting to sound like the "Who's on first" skit.

Pete, wa2cwa
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KA5N
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Posts: 4380




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« Reply #19 on: February 25, 2012, 08:04:26 AM »

No it is more like trying to deal with Sheldon on "The Big Bang Theory"

Allen
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VE3DDY
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Posts: 1




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« Reply #20 on: February 28, 2012, 05:08:44 AM »

I have a 1962 to 1964 vintage Hammarlund HQ-170A that seems to work fine.  I replaced some of the tubes today but in doing that discovered that one of the tubes seems wrong based on the circuit tube diagram.  No, it does not appear to be a standard equivalent and it is not even the same kind of tube.

This tube is used for the HQ-170A AVC circuit and also the AM Detector and 60 KC IF Amp.  Yes, it is three tubes in one.  A 6BV8 that is a triode and two diode tubes in one glass envelope.  However, that is not the tube in my radio.  I have a 6BQ7A which is a dual triode tube -- not the same kind at all except for the fact that they are both 9-pin and use exactly the same kind of tube socket.

When I put the 6BV8 into the socket which is the tube that should be there, the radio does not work.  Well, no signal at all.  But, the 6BQ7A does work and the radio seems to work and all features work (including AGC, mode selection, and so on).

I have not opened up the cabinet but I am guessing that maybe someone modified the circuit for some reason.  Or, maybe this is a standard but odd configuration although the tube diagram plastered on the back of the cabinet shows the tube that should be there, the 6BV8.

So, anyone heard of anything like this?  Maybe this is some well known mod to the HQ-170A.  But, like I said, the radio does work with the exception that the audio seems week but that may be low sensitivity and indicating that alignment might be needed.

Thanks for your help.

I have an HQ-170AC that has been modified somewhat to stop drift.
There is a possibility that your change of tube was done to amplify the AGC and to give better control to the S meter.
If you want to know anything about drift in these 170's I'm your man.
Jim VE3DDY
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W8IXY
Member

Posts: 8




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« Reply #21 on: February 29, 2012, 01:21:23 PM »

FWIW, I have an HQ180a, and found that the 6C4 is a critical point in that receiver.   I had problems with some hum and distortion, not too audible on AM, but very audible on SSB and CW.   I bought 10 New Old stock 6C4's and began swapping them in and out.  I found 3 of them out of 10 worked quite well, with adequate stability and decent CW note and SSB quality.   Its also worthwhile to swap around several samples of the first mixer 6BE6 to get the best performance.

By the way, the "second best" 6C4 had a date code on it from 1945!!    Good luck.

73

Ted  W8IXY
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G3RZP
Member

Posts: 4557




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« Reply #22 on: March 03, 2012, 06:36:29 AM »

Back in the 1960s when my father had his HQ170A (I wish I'd kept it!), we found the same thing as W3IXY with 6C4s and to a lesser extent with 6BE6s.
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