The AM Forum

I just bought a Hammarlund HQ129x.

We don't see as much of vintage amateur (or general coverage) receivers overhere in Holland (or the EU in generaly) as you do in the states.
After WW2 ended, there was a lot of surplus left behind, but civil equipment is more difficult to find.

Last week I was able to score an HQ129x for a reasonable price. The receiver had been in Holland for some years. It was used in the '50's as part of an AM Ham station. When the owner passes away, the receiver ended up in a private collection, and was never used since.

The seller had it hooked up to the power outlet, (I would have done it differently), and reported it still worked.
When picking up, he showed it again and I have to admit, it still has some selectivity and sensitivity. No signs of smoke  :)

I ordered a repro manual. Got it today, so it's time to start a restoration and recalibrate and tune the RF stage and IF filters.

To keep a long story short  ;D
I do have some questions regarding the HQ129x.

1. What does the suffix X mean?

2. The "first" owner in Holland had replaced the 115v (US) hV transformer by a 220v (EU) transformer.
The secundary is 270v-0v-270v. That would mean a DC voltage of almost 380 volt presented at the capacitor input filter. It will probably sag a bit under load, but I would like to know what the original (nominal) DC voltage was. Or the original transformers secundary AC voltage.

3. The owner had repainted the outer cabinet light grey. I would like to restore it in it's original color. Did the cabinet had the same color as the dark grey bezel?
Was it a (Dark grey) wrinkle finish?

4. The serial number is 11115, and has the 15m band on the bandspread dial as well. Does that mean is was a later production model?
If it is, are there more updates done by Hammarlund to this later model?

5 Not seen on pictures of early models, but mine has an 8pins (tubesocket) accesoiree plug on the back. Is this original?

6. As with many receivers, the tuning knobs on mine have been replaced with larger ones. A bit more modern too.
Does anyone have the original knobs for sale?

7. The front panel is still usable, but it started to corode slightly. Next to the corosion, the paint has discolored a lot. Instead of the blue/grey color, it's more coffee colored.
Are there repro panels for sale in the US? Or is there someone who does silkscreen prints the HQ129x panels?

Plan of attack is as follows:
I've ordered capacitors to recap most of the parts. Will check on the resistors too.
Check all the voltages and finaly retune the RF and IF stages according to the manual.

Sandpaper the outer cabinet, and apply a light wrinkle coat (If the original had a wrinkle finish). VHT paint only sels black and red wrinkle paint overhere, but I plan to spraypaint the final color over the black wrinkle layer.

Anyway, every bit of info on the HQ129x is very welcome.

Thanks in advance,

Martin, PA4WM

Hi Martin;
I've restored two 129-X units over the last couple of years.
I may have the original tuning knobs somewhere.  I'll look.
I replaced mine with the HQ 180 tuning knobs and really like them much much better.
Here is some links to a couple of videos I made of the repair and restorations.

If you have a specific question,  please let me know.
I can almost draw the darn schematic by memory now.   It almost got to be an obsession.

What I ended up with is a very very serviceable general coverage receiver that has a special place
in my shack.  It does work on SSB and CW but there are better.  It really shines as an AM shortwave receiver, though.  Many will tell you to just peak the IF transformers and that will work when you do an alignment but you end up with muddy and hollow sounding audio.  I noticed a distinct improvement in AM operation after the "per the book", sweep alignment.  Perhaps Hammarlund engineers really did know something....hi

Lastly,  Yes,  you may have a later model as the 15 meter band didn't come along until well into the production cycle but, there is a possibility that you may also have a retro fit kit.
Hammarlund did offer a bolt on kit with the extra band and it was quite popular.
I can't answer your question on the accessory socket.  Mine did not have one.  The only extra jack on the back was the "relay" control which was a female two pin.

Pete


Adding a crystal calibrator to the 129-X
https://www.youtube.com/watch?v=0uzY-6shuN0

Sweep alignment of the HQ 129-X IF stages.
https://www.youtube.com/watch?v=Dp1R5S8N4dc

Initial repair of the Hammarlund 129-X     WARNING LONG WINDED best viewed with bowl of popcorn
https://www.youtube.com/watch?v=1QSd1xw-6jM

Repair of HQ 129-X mode switch
https://www.youtube.com/watch?v=0xDF_c4T4zo

Continued repair on the HQ 129-X
https://www.youtube.com/watch?v=Wis-2K5lxeM

Video of both HQ 129-X receivers
https://www.youtube.com/watch?v=9kzFokQxPVw

Hi Pete,

thank you for your reply.

In the days before I had made an appointment with the seller, I allready did some research on the net, and have watched your youtube videos. That gave me a feeling that I had done the right thing in buying the receiver without seeing it...  :)

I have send you a personal message as well.

One of the things I really want to check is the DC voltage.
The previous owner ('50's) had  swapped the HV transformer for a 220v primary transformer, to accomodate the Dutch standard.
And while he was on it, he replaced the tube rectifier for a pair of silicon diodes and two 5 ohm dropping resistors.
I know you have to be carefull with that. With silicon diodes, the DC voltage is higher then with a tube. Hence the two dropping resistors.
But in my case, these are only 5 ohm. Good for inrush limitations, but not so much dropping going on there....

The receiver is working even without the planned recapping and realigning, but I would like to know what the original proper DC voltage of the two filter chokes are.
I don't want to overstress my tubes with to much voltage.

Regards,
Martin

Hi Martin,

According to the chart in my HQ-129X manual the DC voltage should read 300 volts at the filamentary cathode pins (2 and 8), of course this will drop as it goes through the filter choke network and should read 268 volts after the first choke.

I have two HQ-129X receivers and I bought a set of original knobs for one.  I quickly discovered why changing them was so common.  The original knobs are really too small for comfortable tuning like the original Comet Pro.

Oops...

I couldn't find it in the manual. And it is just there.  ;D
As it seems, I've been reading the manual with my eyes closed.

Found it, and will check on the voltages.

Thank you.

Martin;
Sent you a PM with the info you requested and some ideas you might find helpful

Pete

I have several HQ-120 and 129 parts widows, so I probably have anything you might need.

73GD