First off, I'd like to thank those who have helped in my previous posts with this set.
It has more problems than I'd like to deal with, but some recent servicing is bringing it around.

So there is no confusion about current (remaining) symptoms, I'll run through a quick list of what's been done to it before, and after I'd received it.

Apparently, a previous owner decided to turn all the slugs to where they thought it sounded the best on the 3kc setting. This is what caused any other KC or sideband setting acting as an attenuator.
I finally got brave enough to run through the steps in the manual. Not as difficult as made to sound, but time consuming. This fixed the KC and sideband switches for the most part.

I have replaced the 80/40/20mfd caps, as well as another 25mfd electrolytic. Any caps listed as "dur-paper" were replaced also. It should be noted that replacing any and all of these caps had NO effect on performance, so it was more or less prevention.

Switches and tube sockets/pins were cleaned.

Here's the problems that remain.

With the noise limiter off and switch to AM there is 60 cycle BUZZ that increases with the volume control.
This buzz goes away when the noise limiter or CW/SSB is switched on.
It also goes away when the 6AL5 is pulled. Replacing with another 6AL5 does the trick until the new 6AL5 warms up. So, any 6AL5 presents the BUZZ. Pulling the 6AV6 makes the buzz WORSE, and replacing it with another brings the BUZZ back to what I normally hear when it warms up. So, any 6AV6 works the same.

There is also a little 60 but much more 120 cycle HUM that is independent of the volume control.

The buzz and hums are gone as soon as the power is pulled (duh), and I can hear a second or two of pure clean signal before the tubes cool.

This is what I am aiming for when its plugged IN!


Next... I bought one of those digital frequency displays that couples the 6C4 with a tube shield. Thats how I found out about the next (possible) trouble.
If the 6C4 in particular is moved in its socket in ANY way, it detunes the signal as if I had moved the tuning knob, and then have to retune the knob to get back on frequency. The tube next to it does the same thing, but to nowhere near the same degree. Yes, they have their shields. Although I dont know if they are the original shields. These shields are the ribbed, squeeze to proper shape/overlap type.
Somehow, I just dont think this behavior is supposed to exist.

The slug in T-12 is cracked. A new one is on the way.

The AVC switch activates the S-meter. The way it reacts is normal? Turning the AVC on switches on the meter, however Slow, there is a lot of reading, medium cuts the meter reading a little, and fast cuts the meter reading even more.

And lastly there are symptoms of SMD. I've read how to rid it of that, and seems straightforward enough.


As always your advice, and input is greatly appreciated, and has helped this set out quite a bit since I first got it.

Looks like you need to start checking the resistors. Usually the higher value resistors are more likely to go out of tolerance so I'd say start there and wirk your way down to the lower value resistors.

Several possibilities here.

1 - someone has messed with the ridiculous negative feedback circuit. Check to make sure you have continuity to ground at any leg of the volume control. As you can see the 27 ohm resistor is part of the NFB circuit, and its junction with the vol control goes to the secondary of the audio xformer thru a 180ohm resistor. I'd also be a bit suspect of C48(?) that 1 uF cap. Check to make sure it's installed correctly, right polarity, etc.

2 - I'm betting you have a combination of H-K leakage, perhaps on the 6BV8, or a tube socket allowing leakage from the heater to another terminal perhaps coupled with a missing ground path on a low level circuit. I't's pretty obvious that the 60 hz is coming from the fil line somewhere - there's nowhere else it can come from - unless it's not 60 hz at all and something is actually oscillating at close to that frequency! In any event the fact it goes away as soon as you remove fil voltage by unplugging it, that's most likely the case (unless there's coupling to the 120VAC somehow).

3 - On that last point, make sure that the audio leads are dressed well away from any 120VAC lines. Sometimes you can get leakage from the power switch on the back of a pot. And you can get leakage thru crud on terminal strips, etc.

My strategy would be to use a .1/600V cap with one end grounded and clip it into each point in the audio signal path, starting from the grid of the audio output tube. You're AC (but not DC) grounding the signal path sao the hum and any audio should go away at each point. When you clip it on a signal path and the hum is still there, the problem is somewhere between the last point you last heard the hum. Getting at it with a scope is another good strategy.

Be prepared to find something miswired or otherwise hammy-hamboned.

If you are using a magnalight to be able to see, shut down the circular fluorescent lamp. I have chased my lamp buzzing through a couple radios.
Pat

So, any thoughts on why moving the 6C4 in it's socket is like wobbling the tuning knob?
Anyones elses HQ series do this?

Could the tube socket pins be dirty? Also it could be that moving the tube around is moving the terminals and depending on the circuit it could affect it just the same as moving a capacitor or resistor that is in one position to another physical position can.

relevant newbie question:
Is it sometimes useful with problems like this to put a temporary home-brew shield between the underside of a socket and the offended (audio or sometimes final IF) portion of a circuit? I've often wondered if tack-soldering a piece of brass/copper sheet between areas of the underside of a chassis would help reduce hum but have never tried it.

Well, wiggling the 6C4 in its' socket does it. Also just touching the bandswitch knob does it to.
Doing this earlier today (wiggling the bandswitch knob) made the GFCI outlet trip..... Somethin' ain't right.

Will look into THAT problem later tonight possibly.
My GF just had her knee operated on, and with me taking care of her, plus the 4 kids in the house, this might end up on the back burner for a bit.
Will keep you guys posted, and thanks again for the hints!

Sprayed the bandswitch assembly with contact cleaner. This didn't improve anything electrically, as I had done it before. But I used a different brand (I think). This made the bandswitch assembly bind up some. While under there I took the liberty of checking, and tightening the barrel that connects the two shafts of the bandswitch assembly together. It was LOOSE, and now I know why. The shafts are somewhat offset from each other. When the set screws are tightened, the bandswitch is much harder to turn. This doesn't make much sense to me as there are flats to be tightened to to make sure the two halves switch with each other.

Now, instead of desoldering everything from the bandswitch wafers, and bending the framework that holds the second half of the bandswitch assembly straight (as well as some rf trimmers).....
How about using one of those whatchamacallits. They have them in an RBL-5 I have and work like they should. Shaft connectors with set screws on either end, but a flexy metal disc in the middle.

I disconnected the barrel, and the first half of the bandswitch clicks and spins freely, and in general feels like it should.
There's also evidence of someone else trying to relieve the stress between the two shafts by putting the set screws somewhere other than the shaft flats. Again, just doesn't sound that good of a solution.

When connected up, rotating the bandswitch visibly MOVES the first half, and components and wires connected to it from the offset/stress from the second half.
Not good!!!
Thoughts on how/why this is the way it is?
Just throw in a flexy shaft connector? What are those things called anyways?

Well, at least now I know why that just pushing on the bandswitch was throwing it off frequency.
I poked around a bit and looked for why wiggling the bandswitch tripped the gfci. I moved a couple things slightly that looked like they were too close for comfort.
Now, having said that, things probably moved DUE to the stressed bandswitch moving them around. Obviously the placement of wires and components is critical to the operation/alignment of the set. Can any error introduced by my shifting things a bit, OR intorduced by the bandswitch assembly moving things around be cleared up with a re-alignment?

Those things are called "flex couplers" but it's still probably going to bind. IMHO you need to find the source of the shaft alignment problem and fix it.

Could be the shaft is bent. I don't recall how the detent assembly is arranged on the HQ-180 - is the detent assembly aat the front of the switch (ie near the front panel) or at the rear? Is the end of the shaft floating, or is there another bearing on the end? You should be able to see which wafer is making the thing bind by close examination.

What I'd do is loosen the bearing where it goes thru the front panel, loosen any other bearings and/or the detent assembly, and try to get things aligned that way if the shaft isn't bent. If that fails, loosen the screws holding each bandswitch wafer to its mounting point, keeping the shaft coupler tight, and let the wafers self-align. You might need to do all of the above, but it's extremely doubtful you'll have to remove any wafers unless there's one that's physically damaged.

BTW you should NEVER, EVER spray contact cleaner on a bandswitch. It gets into everything, soaks into the phenolic wafers, and causes no end of problems. Correct way is with a Q-tip moistened in DeOxit applied to the switch rotors, then crank the switch thru its travel several times. It's beneficial to hold the Qtip against the rotor as it moves, but be careful not to get the liquid on the wafers themselves.

Hmm, the right solution would be to line up the switch shafts-- sometimes you can loosen up the mounting screws and wiggle things around until the shafts line up. This might not work if the chassis has been dropped and warped or if it was out of spec from the get-go.

Or as a last resort, you can put in one of those flexible couplings.

The 2nd half of the bandswitch assembly is held in place place by a piece of framework under the chassis. This framework appears to be leaning slightly towards the face of the radio, possibly factory, as all the leads and connections are in line with this slight bend. Any tugging, or trying to set the framework straight really pulls on leads from the switches to the tube pins, and terminals. So, my best guess is this is the way it left the factory, and leads were soldered accordingly.
So, in order to line the shafts up, the whole 2nd half of the bandswitch assembly needs to be desoldered, THEN bend the framework to line up the 2 shafts, and re-solder.

Thats why I suggested the flex coupler.

I should've said that binding of the switch after cleaning with contact cleaner was notable, but not so bad. It was only after tightening the rigid shaft coupler that the binding REALLY got bad.

Kind of senseless to try and align the radio when with every turn of the bandswitch moves something slightly by the stress introduced by the offset shafts. I won't bother until this stress is relieved one way or another.

The problem is the two shafts aren't in alignment, apparently. If you can't move one, move the other. The first half is held in place by the front panel.

Additionally, it doesn't appear you have the setscrews on the coupler aligned on the flat of the metal shaft. That in itself could misalign the shafts because the setscrew's pressure on the round part of the shaft will necessarily force it to one side.

I'd pull the coupler off entirely, then see how the two ends align together as you crank the bandswitch thru its rotation (be careful to note the original bandswitch position before you do this, so you can sync the two halves again).

There are any number of ways to do this, none of which involve unsoldering switches and all involve loosening stuff up and letting the components reach their natural alignment.

I should've noted that those pics are from the web, and one that a forum member sent me of his 180.
I worked art it a bit. De-soldered a couple leads, and bent the main framework a little to more line up the two shafts. I turns much easier now, and there is far less movement of the assembly. Barely notable. What I DID notice was that tightening the set screws is a main culprit of the offset. Meaning the barrel is SLIGHTLY too big, and the set screws push down on the shafts in the barrel enough to put them out of alignment with each other.


It's as good as is going to get without a flex coupler.

I received the T-12 I'd been waiting for today. Got it soldered in, and all is ok there.

Replaced a few high resistors a couple days ago. Am in the middle of doing voltage readings now. Some are high... some are low.
Will get out the old VTVM for a confirmation here in a bit, as I'm using a digital meter at the moment.

Will post what the chart wants, and what I get later on.
Thanks again!!!!

You wrote: The AVC switch activates the S-meter. The way it reacts is normal?

I can tell you that in my HQ170A, the S meter does drop donw and rest when the AVE is turned off. Actually, I never even new that since I alway have hade it on for SSB dxing. Additionally, on mine the movement doesn't seem to be that much different between low, med, and high settings. Not sure how relevant these nuggets are to your 180A but something to consider. Good luck, I'm on the look out for one of those. I really like the 170A.

The assembly shouldn't move at all, and there shouldn't be any binding.

My original comments on loosening the components and letting them fall to their natural alignments stand.

I find it difficult to believe that Hammarlund would let any piece of equipment get out the door with a major problem like mis-aligned switch shafts.

That problem would be seen by several bench techs, all of whom would have to look the other way.

Just don't seem likely.

Well, it was there for sure. Some of the stiffer leads were soldered in place, and only de-soldering them would allow me to flex that center frame to put the shafts more in line with each other. It's just one of those problems that bugged me. For instance, setting the dial on a frequency, I could switch bands, and move it back to the original band I set the frequency on, and it would be off a little. It was from the slight flexing of the bandswitch assembly, and moving the wires to the oscillator tube a little. It just shouldn't happen. I have the shafts aligned now but with the joining barrel being ever so slightly too large, the set screws push the shafts down a little on each end. The only solution is, tightening the set screws on the most outward points of the shafts, and NOT the flats that are on either side. Or, a flex coupler.

I don't think there should be any stress on the shafts except for one turning the other, and it makes me wish they'd used the single metal shaft through the whole assembly like they did for the bandwidth, and sideband selectors.
One thing I did notice about my 180A compared to others pictures is the center framework for the bandswitch, and RF trimmers. Any other photo I've looked at had extra metal on the bottom where it meets the chassis in a t-square fashion for error free installation. Mine doesn't have this, and without leads soldered to the bandswitch, the whole thing may be bent towards the face or rear. Meaning, whats holding that center framework square to the chassis on mine are the stiff bare leads soldered to the tube pins and terminal strips from the bandswitch!
Perhaps I have a later model?


Those wires from the bandswitch to the oscillator tube are quite sensitive. Even going near them with a wooden poke stick changes frequency.
Wood capacitance..............

And @ w3jn. I did the loosening of wafers and let them fall in line (good advice), as well as fix the leaning framework. I just don't get how it could've been so far off. With the coupler taken off, the misalignment was painfully obvious. The 2nd half was not only pushed down from the rest, but also to one side.

Additionally the 'all thread' that holds the ceramic spacers and wafers aren't exactly the straightest either. There IS some room to wiggle the rotors in the wafers. Forgiving setup in that respect.

The closer I look into this thing, the more I wish I had a history on it.

The final touch would have been loosening the switch at the front panel - of course, that would have meant a couple hours removing all the knobs and the front panel.

I'd think the shaft coupler aligned with the setscrews on the flats would be the best to align the shafts, as both shafts would be pressed against a rounded end and would align better. If there's room inside the coupler, perhaps a piece of thin brass tubing over the two might encourage them to play a bit better together.