[Hammarlund] HQ-170 audio

Sun Feb 20 20:32:48 EST 2011

That's my next step Bob.   Either way, I'm going to have give in and pull it out of it's operating position, which is on a shelf inside a cubicle on the operating bench.

I've just been going on my past experience over the years in servicing tube equipment.

Ray

> From: macklinbob at msn.com
> To: rayfrijr at msn.com; leslocklear at cableone.net; 1oldlens1 at ix.netcom.com; hammarlund at mailman.qth.net
> Subject: Re: [Hammarlund] HQ-170 audio
> Date: Thu, 24 Feb 2011 17:28:09 -0800
> 
> Why not start by pulling the tube that precedes the volume control?
> 
> Bob Macklin
> K5MYJ
> Seattle, Wa.
> "Real Radios Glow In The Dark"
> ----- Original Message ----- 
> From: "RAY FRIESS" <rayfrijr at msn.com>
> To: <leslocklear at cableone.net>; <1oldlens1 at ix.netcom.com>; 
> <hammarlund at mailman.qth.net>
> Sent: Sunday, February 20, 2011 5:22 PM
> Subject: Re: [Hammarlund] HQ-170 audio
> 
> 
> >
> > Les .. The 170A uses an OA2 voltage regulator.
> >
> > One reason I thought the audio or driver is that even with the volume 
> > control all the way down, I can still hear the static crashes, just not as 
> > loud.
> > It would seem to me that if the noise was generated prior to the audio 
> > section, with the volume control down, it would go away entirely.
> > The fact that it remains with the volume all the way down, would seem to 
> > indicate that it is being generated either in the audio driver, or the 
> > audio output
> > because it is still audible. With the volume control down there should 
> > either be nothing driving the audio output tube, or if it were in the 
> > driver tube the
> > noise being generated in the driver was being supplied to the audio output 
> > tube.
> >
> > I must admit that I have never seen a voltage regulator tube cause static 
> > crashes, so I find that interesting Les.
> >
> > In my experience, I have found tubes exhibiting microphonic noise 
> > response. Usually a tube presents that problem due to the elements 
> > wiggling or aging
> > and becoming susceptible to vibrations such as occur with the tapping of a 
> > front panel, chassis or cabinet. The vibrations are transmitted into the 
> > tube,
> > causing the microphonic sounding noise, which sounds different from the 
> > "static crashing" type of noise one hears from a bad tube.
> >
> > I have used the "tube tapping test" over the years too. I havent tried it 
> > yet because I will have to pull the receiver out of its position on the 
> > operating bench.
> >
> > My thoughts on making the inquiry about anyone having spare ones to part 
> > with was to get ready in case it comes down to that being the cause.
> >
> > Ray
> >
> >
> >
> > From: leslocklear at cableone.net
> > To: 1oldlens1 at ix.netcom.com; rayfrijr at msn.com; hammarlund at mailman.qth.net
> > Subject: Re: [Hammarlund] HQ-170 audio
> > Date: Sun, 20 Feb 2011 18:40:14 -0600
> >
> >
> >
> >
> >
> > I have seen voltage regulator tubes make static crashing noises on several 
> > different receivers, including a R-390A and SP-600. I don't have a book 
> > handy, does the 170A use an OA2 like the 180A? Swap regulator tubes just 
> > to eliminate that as a source. Or, tap on the tube with a wooden lead 
> > pencil eraser.
> >
> > Les Locklear
> > Gulfport, Ms.
> > DX'ing Since '57
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > ----- Original Message ----- 
> > From: Richard Knoppow
> > To: RAY FRIESS ; hammarlund at mailman.qth.net
> > Sent: Sunday, February 20, 2011 6:30 PM
> > Subject: Re: [Hammarlund] HQ-170 audio
> >
> >
> > ----- Original Message ----- 
> > From: "RAY FRIESS" <rayfrijr at msn.com>
> > To: <1oldlens1 at ix.netcom.com>; <hammarlund at mailman.qth.net>;
> > <boatanchors at puck.nether.net>
> > Sent: Sunday, February 20, 2011 3:35 PM
> > Subject: RE: [Hammarlund] HQ-170 audio
> >
> >
> >
> > The microphonics are still present even with the volume
> > control all the way down.
> > The noise (static like crashes) decrease with the volume
> > control all the way, down but are still present, just barely
> > though.
> > By microphonics, I mean that when I tap the cabinet or front
> > panel, you can hear the coming through the audio section.
> > Before the noise started in the audio section, it was not
> > present.
> >
> > I have had the receiver gone completely through by an expert
> > in Hammarlund receivers. When he sent it back after going
> > through it,
> > he said it was as close to factor specs as he had ever been
> > able to get a receiver of its age to.
> >
> > Ray
> >
> > There may be two different problems. If the "static"
> > goes away with the volume control down its generated ahead
> > of the audio stage. You may be able to isolate it by pulling
> > tubes to see what makes the noise go away.
> > The microphonics may be from a bad tube but I again
> > suggest tapping and poking at things to see if you can
> > isolate it. Without another tube to substitute its difficult
> > to isolate it to the tube but even if another tube works
> > better it may be that the socket or tube pins are oxidized
> > which can also cause a similar microphonic problem. Cleaning
> > the pins with a toothbrush or even a Brillo pad and cleaning
> > the tube socket with some Deoxit and then working the tube
> > in it may help.
> > Don't count on your "expert", there may still be
> > problems.
> > Neither of the audio tubes is rare or expensive and a
> > web search should find some at reasonable prices.
> > Unfortunately, few tube testers have any means for
> > testing for microphonics. I will say that its normal for
> > tubes to have just a little but not what you describe.
> >
> >
> >
> > --
> > Richard Knoppow
> > Los Angeles
> > WB6KBL
> > dickburk at ix.netcom.com
> >
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