Hammarlund HQ-140-X

Discussion in 'Amplitude Modulation' started by KA4KOE, Jul 17, 2019.

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  1. K9STH

    K9STH Ham Member QRZ Page


    The HQ-120X, HQ-129X, HQ-140X, and HQ-150 are all, generally, more stable than any of the other Hammarlund receivers including unmodified Super Pro series receivers.

    Glen, K9STH
  2. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    That drift problem apparently is inherent to the mechanical design of the tuning capacitors in the Super Pro series. This includes the SP-600, which is a great AM receiver (except for one thing) but not so great for CW or SSB; they never seem to stop drifting even if left running all the time. The one thing that isn't so great about the SP-600 even for AM is the backwards tuning. In most equipment, convention is that turning the knob clockwise takes it up in frequency. In the SP-600 (and I don't recall with the older super-pros but probably they too), turning the knob clockwise tunes down in frequency.

    The Collins 51J series is a mixed bag - some bands tune upwards and some downwards, due to the mixing scheme. The backwards tuning bands are marked in red on the slide-rule dial. With the 75A-2, 3 and 4, 160m tunes backwards for this same reason and the scale is marked in red.

    Collins corrected the backwards-tuning issue with the R-390 series by using a different conversion scheme, which is triple-conversion on some bands.
  3. K9STH

    K9STH Ham Member QRZ Page

    The truth be known, the Collins 75A-1, 75A-2, 75A-2A, 75A-3, and 75A-4 are all only a receiver that tunes from 1500 kHz to 2500 kHz. The other bands are crystal controlled converters that have the injection frequency above the received frequency which reverses the tuning. The 75A-1 does not have access to the basic receiver like is in the other A-Line receivers. However, a fairly simple modification can add the 160-meter band but there is no dial scale unless one is added on the outside of the slide-rule dial.

    With the 75A-1, 75A-2, 75A-2A, and 75A-3, the PTO frequency is doubled on the top 2-bands (26.0 MHz to 28.0 MHz and 28.0 MHz to 30.0 MHz). As such, the kHz dial (round dial) has a separate scale for the top 2-bands with "2 kHz" ticks instead of 1 kHz ticks like the other bands. Of course, for all the A-Line receivers with the 160-meter band, one scale is reversed from the other scales.

    The 51J- series / R-388- series are also a basic receiver with crystal controlled converters. The mixing scheme does reverse a couple of the tuning of the bands from the others.

    I do have a 75A-1, 75A-2, 75A-3, 75A-4, 51J-2, and an R-388 (51J-3). Years ago, I did own an R-390 but got an offer that I could not refuse to sell the receiver.

    Glen, K9STH
  4. N6YW

    N6YW Ham Member Volunteer Moderator QRZ Page

    I would include the SP-10 & SP-100/200 in that line up.
    I have owned practically every model Hammarlund receiver ever produced. Currently, an SP-10, 2 SP-100’s and SP-200 are lined up for restoration in my collection.

    Before it needed attention, my number 2 SP-100 was as stable as any receiver I’ve owned that was produced before 1970.

    However, like many of the receivers built in this period, good stability above 15 meters wasn’t generally that good if they didn’t include calibrated
    bandspread tuning.

    The HQ-140X is a fine receiver and once Fleep
    gets his ironed out, he will likely keep it and use it often.
  5. K9STH

    K9STH Ham Member QRZ Page


    There are, of course, individual exceptions to the Hammarlund drifty receivers. For AM operation, below around 10 MHz, they are usually fine and are, generally, OK on 20-meters. However, for SSB and RTTY operation, almost all of the Super Pro receivers are just not stable enough for extended operation without modification. When proper temperature compensation, etc., is added, they they usually settle down quite a bit.

    The SP-600 JX- series receivers were used extensively for RTTY links. However, they were crystal controlled and did not use the normal frequency tuning.

    Over the decades, I have worked on a fair number of all of the various Hammarlund models and they, generally are very drifty above around 10 MHz except for the HQ-120X, HQ-129X, HQ-140X, and HQ-150.

    Glen, K9STH
  6. N6YW

    N6YW Ham Member Volunteer Moderator QRZ Page

    The HQ-170 was the worst of any I’ve owned.
    A full re-cap and alignment did nothing to improve
    performance. Even after a warm up of 30 minutes, the drift on 40 & 75 meters was unacceptable.
    Anyway, enough thread derailment from me.
    I saw a video where Fleep was able to get the 140
    up to speed and sounding good?
    Congrats Fleep!!!!
  7. KM1H

    KM1H Ham Member QRZ Page

    There are caps under the BFO coil shield on the bottom side. Many miss that step.
  8. KM1H

    KM1H Ham Member QRZ Page

    The 170/180 series drift solution is manageable but not a fast process. It requires some work to the 6C4 HFO plus eliminating all other causes first.

    My modified 180 can now monitor any band SSB for long periods without intervention. Not as good as my NC-300 but acceptable.

    The primary cause of HQ-120 and others with similar circuitry is the HFO trimmer caps. Replacing the offending ones with subminiature Johnson air variables takes care of most of that plus works on many other brands, especially Hallidrifters.

  9. K1SZO

    K1SZO XML Subscriber QRZ Page

    I just picked up a Hammarlund HQ-129X from W1ZR over the weekend. It will be part of my first old analog radio station. (I mostly have SDR's with the exception of an FT-450D) I will add it to my Heathkit SB-221 (/w 10m mod) amplifier. I just need a transmitter now.

    I'm hoping to learn to repair / refurbish these old devices too.
  10. K4KYV

    K4KYV Premium Subscriber Volunteer Moderator QRZ Page

    With classic hollow-state receivers (and transmitters), nothing I have ever used equals the Collins-type PTO for stability.
    WZ5Q likes this.

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