[Boatanchors] HQ-180 Need Help

[Barry H]

Hi John

Looks like that HQ-180 is providing quite a workout -- an object lesson and very high "tinker value".    Some more thoughts interspersed below:

-- "John Page" <k4kwm at hotmail.com> wrote:
>Thanks to all who responded.

>Not sure who sent me to antique radio forum, but that was a big >help. A push on one of T-1's terminals and I heard some crackeling >noise. At the time I also had the generator and VTVM on so I could >have a steady reference. The signal level almost doubled.


I think someone else on the list also mentioned something about a transformer.  One falure mode on IF tranformers is fairly simple -- the connection of the winding/litz wire to the solder terminal on the inside of the can.  You might need to open it up and re-solder it.


>I also found low voltage (44volts) on the screen of V18. That is the >455kc gate. A 6BA6. It should be 88volts. I changed the screen >dropping resistor and screen bypass cap. Still 44 v. I pulled the >6BA6 and it went to 88 V. ?????????

One roadblock in solving problems logically is in "incontrovertable" conclusion that's based on solid logic.  The downside -- one of the assumptions is faulty.  For example, tube swapping should logically be a way to rule out a faulty tube, right?  Even the military tube manuals almost all include the disclaimer that the true test is the tube in the circuit.  However, we overlook the possibility (odds assumed remote) that several subs are bad.  Offhand unlikely, but the question is -- where did the other 6BA6's come from?  If from the same sleeve/lot, could be defective.  Gain can be good, no shorts, etc. but there may be grid emissions.  In some sockets/applications, this won't cause much problems -- elsewhere, not so.  Try one or more from a working receiver or be sure to test for that on a tube tester.  Some have a dedicated test for it, but I thinks it's basically the same as the gas test.


>Tried several other tubes and still the same. Even tried a 6BZ6. >Same thing. All other voltages on the 6BA6 are correct and the >resistances are all correct. EXCEPT for pin 6, the screen. With the >new components the resistance is correct. Could I have a bad tube >socket?????

Seems remote, but possible.  I forget if they are black bakelite or tan phenolic color.  Look for possible carbonization, arcing tracks.  I dunno.


>I did clip lead an 18 K 1/2 watt across the 47K screen resistor and >ended up with about 85 volts on the screen.

>This also helped a lot. Did another quick alignment and now bands 1 -> 2  and 5 - 6 are pretty hot. Bands 2 - 3 are still pretty much dead.

The 180 is triple conversion -- triple on some bands, double on others as I recall.  Do the working/not working bands correspond to the conversion scheme?

>I still havent pulled T-1. But the pushing of the feminal sure >changed the T-1 alignment.

The other bum steer in debugging things is the presumption that one defect is causing the problem when there is more than one.  For example, you may have a bad connection inside T1 AND something else affecting the high bands.


>For what its worth, I have been finding little stupid things that >people have been doing to the thing over the years. Like a 90 volt >VR tube instead of a 140 volt one. Talk about low screen voltages.

>Also someone cut the ground wire for the cal trimmer. Had nothing to >do with present problem of course.

>They also had the antenna input wires reversed on the bandswitch. >Found that early on though.

Yet another source of misleading assumptions -- that the device in question conforms to the original design/schematic.  Once you see one thing changed, you can't assume anything else is "as-was".  Even without that, there are often undocumented changes in manufacturing runs and variations in physical wiring -- such as the use of certain unused tube socket terminals as tie points.

>Will next try the "test the ground" trick. That ought to be fun. But >it sure makes sense.

Yup -- especially because it's a rivet job -- whole thing depends on electrical connections made between dissimilar metals -- I guess plated rivets to aluminum and whatever is pinched in between.  Amazing that they work for 5 years, let alone 40 or 50.  

>Anything else you guys can come up with will really be appreciated.

>Maybe I will keep it after all.

Sounds like a "keeper" to me.  Plenty of play value -- which is good -- because there's many a night when there's nothing worth listening to. ;-)

>I need to check the 170 as it is slightly deaf. Maybe its T-1 or >whatever it is in a 170 is also going.

>I have an HQ-145 and it had a similar problem but it was a problem >with low injection into the mixer. It is really hot now and my >favorite receiver.

There ya' go.  When this 180 is fixed, it will probably be your most highly tweaked radio.

Barry





                       Thanks again, John

John Page K4KWM
Hollow State since 1953
(ex W8PKU,N8BLB,NA8O)




>From: "John Page" <k4kwm at hotmail.com>
>To: boatanchors at mailman.qth.net
>Subject: [Boatanchors] HQ-180  Need Help
>Date: Sun, 27 Nov 2005 19:28:31 +0000
>
>I picked up a very nice looking HQ180. It even worked great. Now it is deaf 
>as a post. I can hear WLW on 700KC quite loud and a couple other broadcast 
>stations. Nothing on band 3. A little on band 4. Band 5 and 6 sometimes. 
>When a station is found it has very bad qsb.
>
>I have done a complete alignment by the book using an HP-606A generator, HP 
>freq counter, and an HP-410B vtvm. All tubes were checked and reinstalled 
>one at a time. I even swapped out most of the tubes one at a time into my 
>HQ-170.
>
>Alignment on these things is complicated but not that difficult and I have 
>gone through it many times.
>
>It will work pretty good and then it will go deaf.
>
>Sometimes, and this ought to be a clue, it wont work at all and I just 
>click the onoff switch on the power strip on the bench and it comes to 
>life. But so far I havent been able to find the problem.
>
>Also all voltages and resistance measurements are as noted in the manual 
>charts.
>
>Also, for what its worth, I hooked up an Ameco nuvistor preamp and when I 
>find a signal on the band, the preamp will really bring the receiver to 
>life. I am talking about s2 to 3 signals going up to 40 db over s9.
>
>I am nowhere near the tech some of you guys are but can usually get one of 
>these things going.
>
>Anybody got any suggestions? I am ready to get rid of the thing but hate to 
>as it was a present from my wife.
>
>Maybe someone on the list works on Hammarlund and would let me ship it to 
>them for repair.
>
>Thanks in advance for any help.   John
>
>John Page K4KWM
>Hollow State since 1953
>(ex W8PKU,N8BLB,NA8O)
>
>
>
>
>>From: "david knepper" <collinsradio at adelphia.net>
>>To: <boatanchors at mailman.qth.net>
>>Subject: [Boatanchors] 6AM5
>>Date: Sun, 27 Nov 2005 11:45:49 -0500
>>
>>Need two for an Eddystone 770R receiver.
>>
>>Thank you
>>
>>Dave, W3ST
>>Publisher of the Collins Journal
>>Secretary to the Collins Radio Association
>>www.collinsra.com - the CRA Website
>>CRA Nets: 3805 Khz every Monday at 8 PM EST
>>and 14255 every Saturday at 12 Noon EST
>>
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>>
>
>
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>


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