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 Post subject: HQ 110 restoration
PostPosted: Jan Wed 09, 2019 8:26 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 123
Good day,

I am working on the restoration of a HQ110 for the grand children. They are
interested in learning the code!

Is there a source for some of the Hammarlund unique items. I am
some what ok on R,L and C's. However, knobs and transformers, IF and
any other would be an issue. Thanks! Alan


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 1:50 am 
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Location: Costa Mesa, California
I have a junker HQ 110 if you need some parts. No knobs and missing a few things, but has the transformers and other items. I would not expect your radio to need much. Hammarlund used quality construction from what I have seen.

Norm

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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 2:01 am 
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Joined: Nov Wed 17, 2010 11:14 pm
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Great Norm. I appreciate the reply!

I'll be digging in over the next couple a days and see what I have.

73' Alan


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 1:58 pm 
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Alan,

Hopefully you won't need to replace any transformers. Hammarlund used the same knobs across many units so those will be easy to source.

Most capacitors are ceramic disc types and will be fine. You do need to replace the filter caps and the cathode bypass cap for the 6AQ5 audio output stage and I would do these before any power on testing because a failure of any of these three caps can damage the power transformer, filter choke, and audio output transformer.

After you power it up for the first time, check for any positive DC voltage on the control grid of the 6AQ5 stage and check again a few minutes later; if there is positive voltage then the audio couplate has a leaky capacitor and should be replaced immediately. You can use discrete components for these now very difficult to find "integrated RC circuits". It is important to make this voltage check because a positive grid voltage will greatly increase the current draw of this stage which can destroy power supply components and the audio output transformer.

You don't often find severely out of spec resistors in this line of HQ series receivers so between good resistors and the use of ceramic capacitors you probably won't need to replace any components other than the electrolytic caps.

The HQ-110 is a good quality dual conversion receiver. It is often confused as being just the ham band only version of the entry level HQ-100 receiver but it is actually a big step up from it; the HQ-110 when used with the Hammarlund HC-10 SSB adapter provides virtually equivalent performance to its HQ-170 big brother.

Rodger WQ9E


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 5:08 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 123
Many Thanks Rodger for the heads up!

I will check this out. I assume you are addressing the Z1 network between the 12AX7 and the 6AQ5 V8.
If not, let me know. I see you also mentioned C73C 25 uF cathode bypass. Better check that! While I believe C73A and C73B are no longer connected, see comments below.

At this point, the receiver is serial ~7900+ so I guess it falls into the 3rd class of production units. The LO
appears to be running and stable. However, deaf on 160-80 meters. Not too awful on 40 meters and appears
deaf on 20 meters. The unit has in place the solid state 5U4 rectifier sub and the HV power supply caps were
replaced at some time with a pair of 100uF 450 V caps. The original canned cap is still in place, just disconnected.

The radio is far from perfect, however, all the essentials are there and the fact that sensitivity on 40 meter CW is better than 0.5uV
implies hope! Under the assumption that I rule out any time bombs like the one you mentioned in your post, I plan on troubleshooting
the radio to determine what is at fault. Deaf on 80 and 20 and not shabby on 40 is a bit confusing unless we have a faulty band switch.
I have NOT checked tubes, tube voltages or tubes pin resistance at this point. A little deoxit on some key points may go a long way to
bringing this receiver back to life.

Again, thanks all for any and all input.

Alan


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 7:49 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 123
I checked the replacement of C73A and C73B and that is completed with 450WV 100 uF.

However, the cathode bypass using that same multi-cap can is still in use. I see the bypass connection runs from one end of the chassis 6AQ5 location to the cap on the other side!

I'll place 25 uF directly at the 6AQ5 socket terminal-2.

I'll take a look at the Z1 coupling network.

So going forward, I do not like to shot gun replace parts. I'll choose a band, say 80 or 40 meters, and try to make sense of why things are not functioning. The conversion scheme on 160-80 and 40 and above are different. Perhaps I will get a hint as to what is going on in the troubleshooting process.

Any other thoughts? Thanks! Alan


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 10:09 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
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I removed the 6AQ5 cathode bypass cap as used from a section of the main supply filter. Mounted a 25 uF 100WV directly at pin 2 of the socket. All measured voltages on the 6AQ5 pins match the chart quite well. I set my variac so that at the plate of the 6AQ5 I see 260 V. I'll proceed to do voltage checks on all tubes in this manner.

On the Z1 RC couplet network. It appears to be fine. There is no positive V on the grid. It is essentially at zero volts. I would say the blocking .01 uF within the coated hybrid is in tact.

Thanks, Alan


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 10:47 pm 
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Alan,

Something I didn't read carefully earlier was that the original caps (20 uf) were replaced with 100uf plus a solid state rectifier. This should have really increased the B+ along with greatly increasing the current draw of the transformer since the repetitive charging current is much higher. The 100uf on the output side of the choke is OK but I would change the 100uf on the input side to a 22uf AND you should also add a dropping resistor to reduce both the voltage and the peak charging current unless the solid state replacement already has a resistor built in.

I have gone to solid state rectifiers in a number of pieces of gear when there is a good reason to do so but in those cases I use a dropping resistor to compensate for the greatly reduced voltage drop across the solid state rectifiers and I also add an inrush limiter to the primary feed; both of these are important for the health of your power transformer.

When certain bands are dead the first thing I would check is whether the local oscillator is working. With the HQ-110 the local oscillator operates 455 khz. above the dial frequency on 160 and 80 meters and 3.035 above on the other bands although it MIGHT operate with low side injection on 6 meters (3.035 Mhz. below instead of above, I can't remember). You can use an external receiver tuned to the expected LO frequency with an antenna lead near the oscillator tube, for example tuned to 3.5 Mhz. on 80 meters you should hear the oscillator at 3.955 mhz.; for 40 meters you should hear the LO at about 10.035 Mhz. when tuned to 7 mhz. Of course the calibration won't be perfect so tune around the expected frequency.

The HQ series of receivers are very particular about the 6C4 used so it is good to have a few spares to choose the one that works best in your receiver. I doubt if the 6C4 is the only reason your HQ-110 is dead on certain bands since it does work on 40 but not 80 but nothing would completely surprise me with some of the odd behavior that circuit has caused. I have no idea why the 6C4 circuit is so picky in this line of receivers but a lot of us have experienced issues with it that are cured by a different 6C4. A tube tester is useless in evaluating tubes for this circuit, only testing in circuit will be useful.

Rodger WQ9E


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Thu 10, 2019 11:59 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 123
Yes Rodger. When I saw the SS rectifier and :( the larger electrolytic I was concerned. For now I have a variac to help control main supply B+. I will follow your lead and make those changes. I think long term I will return the supply back to tube. The SS unit is model T-SSR01 from Antique Supply I believe;

https://www.tubesandmore.com/products/s ... -5y3-tubes

On the other items, agree. I have a frequency counter etc...

My first course of action is to get the main supply reasonable, measure tube voltages and tube pin R values and see if any thing jumps out. If not, then mover forward with signal injection, scope and spectrum analyzer to determine "what is NOT working?" or "what does not make sense".

I'll re post when I have a better set of observations.

Alan


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 12:51 am 
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Location: Ohio 45177
I had one at one time and never did get it going because the RF gain pot was bad. And it is an oddity as I recall so I would have needed the pot from another of the same. Pretty sure it was the RF gain. Not the audio, anyway.


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 3:13 am 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 123
Thanks wazz. I hope I don't get involved with any unobtanium parts...

It is helpful to know what HQ110 are you working on anyway??? Ok, turns out this one despite its serial number below 8000, S/N 7954, follows the traces of the HQ110A. It does not have 6 meters. It does use the 2.580 MHz xtal LO, not the 3.49 MHz LO of the earlier model(s).

So on 160 and 80 meters the 2nd converter tube V3, acts as a 455 IF amplifier (my words) and the 6C4 HF LO is running at 455 kHz above the Rx frequency. Hence conversion is straight down to 455. While on 40 meters and higher, the HF LO is operating on the receiving frequency PLUS 3.035 MHz. The 2nd conversion is in V3 again which also is operating as a mixer and a LO at 2.580 MHz. The difference is 455 kHz. In other words, V3 plays a DUAL role; IF Amplifier at 455 for 160 and 80 meter operation, OR MIXER-OSCILLATOR, that is CONVERTER on 40 meters and above.

In this HQ110 model, the power supply filter caps were UPPED in value, from 20 uF each to 40 and 60 uF each. All at 450 WV. Whew... Its hard to troubleshoot something until you are on the same page with what's sitting on the bench.

Still scratching the surface. Thanks!


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 4:33 am 
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Location: Liberty, Missouri
I bought an HQ-110 at the Shriner's ham fest last year. A nice little radio. You should be pleased with it's performance once completed.

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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 5:30 pm 
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Joined: Jul Tue 21, 2009 1:38 pm
Posts: 918
Location: SW WA state
rsingl wrote:
and I also add an inrush limiter to the primary feed; both of these are important for the health of your power transformer.


Rodger: Curious as to what you are using for inrush current protectors for receivers (ca. 1 Amp draw). I've been using CL-60's (which are a 5 Amp part). Is there something closer to a 1 or 2 Amp rating that works better?
Many Thanks!

-Tom


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 6:47 pm 
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Hi Tom,

For most receivers I think a CL-170 (2.7A, 16 ohm) or CL-190 (2.4A 25 ohm) would be a good choice. When I looked at the application sheet a LONG time ago the recommendation was to choose a part where the expected equipment draw was to be between 60 to 80% of the component rated level. But I don't think it is that critical unless you use a part that is rated so high that it doesn't drop the resistance down to the desired near zero value once it heats up.

I bought a HRO-5 with matching doghouse supply many years ago and it had been restored before I bought it so I never went into the power supply but I should to see what inrush limiter was used. It takes about 30 seconds for the panel light to come up to full brightness so whatever was used probably has a much higher current rating than needed.

For a transmitter you want to be reasonably close for the plate supply so it doesn't have a slow ramp-up on initial activation of the plate supply for AM (or the first CW character). The thermal lag is great enough that once heated up it won't cool between CW characters so that isn't an issue. The thermal lag on cool down is a bit of an issue because if you activate the plate, drop it, and then immediately reactivate the plate you will get a surge on the second activation but it certainly won't be any worse than the original design and probably less since the filter bank may not be fully discharged during a short power failure.

With my homebrew amplifier I do use a current limiting resistor shorted by a R/C timed relay to control initial charging current of the large oil filled capacitor bank for the HV supply and for safety a spare set of contacts of that relay is in series with the PTT line so if the relay fails to close the amp cannot go into transmit which would cause the current limiting resistor to explode. That is a mistake made in some commercial amps that use a timed relay circuit to limit initial surge and if it fails to close when transmit is attempted the full current tries to go through the current limiting resistor which will take out other stuff when it flames out. The advantage the relay circuit has over a thermal inrush limiter is it resets pretty much immediately if the power "glitches" so the power supply will restart in the current limited mode but that isn't needed for most equipment.

Rodger WQ9E

Rodger WQ9E


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 7:29 pm 
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Joined: Jul Tue 21, 2009 1:38 pm
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Location: SW WA state
Thank you, Rodger! I'll add the CL-170's and -190's to my bag of tricks...

73, -Tom N1BEC/7


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 7:31 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
Posts: 123
Thanks again for inputs.

This is where I am with the HQ110.
I made some rough sensitivity measurements on 160, 80, 40 and 20 as well 15 meters. All CW mode. I set my variac so the tube voltage on the SS 5U4GB pin 2 and 8 are 263 V. Chart called for 270 V. This gave me a number of random tube voltage readings all well within the chart specs for the audio, Q multiplier, and voltage regulator. Getting readings of the RF amplifier and 1st mixer as well HF oscillator are tough. Tight quarters! Anyway those tube readings may be academic as I have the following:

RF input for reasonable S/N
160 meters DEAD!
80 meters -110 dBm
40 meters -110 dBm
20 meters -100 dBm
15 meters -90 dBm

I am not quite ready to grab an alignment tool.
There are a couple of items that don't quite make sense.
On 40 meters with generator OFF tuning across the band I hear every 100 kHz or so a rushing increase in noise. Sounds like a noise birdie. The CAL is OFF. Otherwise across the band, noise floor sounds quite fine and low. On 20 meters, the noise floor rise is significant. It also can be adjusted in level with the antenna trimmer. In all cases I tuned the antenna trimmer for best S/N. The generator is 50 ohm and the HQ110 antenna terminals have one side of A grounded. Operation is single ended. The dial readout on all bands is off about the same amount, about 50 kHz. It would be an easy fix by just loosening the freq dial coupler
and rotating the disk. Have no clue what's going on with 160 meters. Open front end tuned circuit?

At this point I am thinking clean and de oxit tube pins and sockets and band switch gently. Not sure I can get any contact cleaner into RF sens and vol control and actually they are not very noisy. Finally, look at changing out RF amplifier and 1st converter tubes and see if they have any effect on the band-to-band sensitivity as well as the strange rise in noise on 20 meters and noise birdies I hear on 40 meters. COMMENTS? Thanks!

Alan


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 8:42 pm 
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Joined: Nov Wed 17, 2010 11:14 pm
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I was able to get a scope probe on pin 1 of the mixer V2. Indeed the LO frequency in relation to the dial reading is in ERROR! And it appears to be in error by the same amount on all bands. However, better double check. If that is the case then a simple rotation of the dial will fix this issue. I'll also check the injection volts, p-to-p for each band. It is present on the 160 meter band, so its not lack of HF LO causing that band failure.


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 9:17 pm 
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Location: SW WA state
SOP for working on equipment, especially vintage, is to clean all of the controls and switches first, test tubes, and look for physical damage.
Then I carefully run the equipment up to line voltage with a Variac, looking carefully for any signs of catastrophic problems.


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Fri 11, 2019 10:01 pm 
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Alan,

Start by making sure that the dial is properly indexed to the tuning capacitor or you will be going in circles with alignment. Check your manual but I believe the setup is the same as for the HQ-170 which I just went through last month so I remember it. You have to first carefully fully mesh the tuning capacitor and then loosen set screws and adjust the dial scale so that the pointer indicates the index mark which is just below the low frequency end of the scale, this provides a slight tuning overlap below the low end of the calibrated scale. After you do this turn the tuning knob so that the marker is exactly on the low frequency end of the scale and then loosen the other dial scale and set it so that it also indicates the low frequency end.

Rodger WQ9E


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 Post subject: Re: HQ 110 restoration
PostPosted: Jan Sat 12, 2019 4:10 pm 
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Thanks Mike, Tom and Rodger for more advice.

Tom, evidence of cleaning was apparent last evening. Decided to try the AM mode and S Meter with switch to the REC from CW mode. The sig gen was set for AM at -80 dBm. Zilch audio in the AM mode. Monitoring the pin voltages on V7, 6BJ7 showed no V change. Removed the tube, re inserted and continued to probe tube socket pins and switch the function switch back and forth from REC to CW. Finally after the 3rd try AM demod belched out. And the S meter came to life. I guess I need to go through the unit carefully with either iso-propyl (some 91%) or D5 de oxit.

Rodger, I'll follow the HQ170 approach you outlined. It does appear that all bands zero point (7.0 MHz, 14.0 MHz, etc.) are shifted by an identical amount, about 40 kHz UP. In other words main tune cap plates are opened slightly, not fully meshed. There appears to be more than sufficient over run on the cap rotation to accommodate proper setting. Hard to believe all HF LO coils aged exactly the same!

Alan


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