Cryogenic cooling in ham radio

Discussion in 'General Technical Questions and Answers' started by N5HXR, Jul 2, 2021.

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  1. N5HXR

    N5HXR Ham Member QRZ Page

    I'm going through a survey course on radio astronomy, and wondered about parallels with amateur radio. We just went through the basic design of a receiver for astronomy use, and that includes cryogenic cooling to eliminate thermal noise.

    I wondered whether there are any corners of ham radio where cryogenic cooling of a receiver is useful or common.

    Do EME guys chill their receivers?

    Would a cryogenic receiver make a difference in any amateur radio activity?
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Amateur Radio operators tend to focus more on cooling their adult beverages before turning the radio on. :)

    It is typically easier to build better antenna arrays for gain, than cooling radios.
    AC0OB, SWL37632, W3WD and 1 other person like this.
  3. K6CLS

    K6CLS Ham Member QRZ Page

    Some amateurs with large dishes, like 10m diameter, are looking at pulsars on 400MHz and 1400MHz. But using modern FET preamps. Not sure if cryogenic temperatures would help at those frequencies.

    Check out the work by Mario I0NAA.
    PU2OZT and N5HXR like this.
  4. N5HXR

    N5HXR Ham Member QRZ Page

    Hmm... 10m dishes sound pretty cool! All the discussion in this evening's lecture was of frequencies from 1.4GHz to 35GHz. Hydrogen, ammonia, and other atomic or molecular spectral lines.

    The receiver prototype the lecturer showed from the Green Bank Observatory was cool (hah, pun intended i guess). Pretty fancy gear.
    KA0HCP, PU2OZT and N3RYB like this.
  5. SWL37632

    SWL37632 QRZ Member

    Typically, Amateur Radio Astronomers do not cryogenically cool there radios ....BUT, some very dedicated folks have used containers and dry ice to cool the front-ends of their set-ups. They do claim some higher performance...(lower noise) as a result....but they are the exception.

    There is an equation that you can use to do 'what if's'.
    I looked at this a few years ago and decided that it wasn't worth the effort for me.....very little performance increase for the equipment and effort to be expended.

    Plus, you need to make your trades given the specific local environmental RF noise level versus what you might gain performance wise.

    While in grad school I visited the Goldstone Deep Space facility under a special JPL/Caltech invite.....there is a reason why they located that facility far away from 'local' noise sources on a military guarded reservation area that at the time didn't allow public visitors......

    They used substantial cryogenics and fed the working fluid directly to the horns at the foci of the various dishes there....

    The 64 meter (now 70 meter) dish was quite impressive. A tour by the Chief Engineer of the comm and data collection system was equally impressive.

    20+ WPM 1970's Extra
  6. NN4RH

    NN4RH Premium Subscriber QRZ Page

    I searched the ARRL QST/QRX database and found nothing about cryogenic cooling of ham receivers. That doesn't mean it has never happened, of course, but if it has, it didn't get published in QST.

    I suppose that internally-generated noise in ham radio equipment is not likely to be the limiting contribution to noise in usual ham radio activities, so there's nothing to be gained by such cooling.

    However, it's possible that someone who is a ham, might also be into amateur radio astronomy, amateur SETI, or receiving extremely weak signal telemetry from space/planentary probes, and might go to such lengths, but that's outside the scope of the ham hobby.
    Last edited: Jul 2, 2021
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  7. AC0OB

    AC0OB Platinum Subscriber Platinum Subscriber QRZ Page

    Unless you are trying to measure CMBR or are cooling superconductors, probably not.

    Atmospheric noise usually swamps any thermally generated preamplifier noise in amateur receivers.

    WA9SVD likes this.
  8. N4DJT

    N4DJT Platinum Subscriber Platinum Subscriber QRZ Page

    Closest I've come to cryogenic cooling is reworking PC CPU Water cooler blocks and radiators for solid state amps.
    There are some serious PC Over-Clockers that do use cryogenic cooling in extreme cases.
    Bet that could be adapted for Ham radio use also? Might be an interesting experiment?

  9. SM0AOM

    SM0AOM Ham Member QRZ Page

    There are some Swedish EME amateurs that have investigated Peltier cooling of 23 cm preamp. They have used a scheme developed at the Onsala Space Observatory, and it was possible to reduce the noise figure of a good preamp from 0.2 to 0.12 dB, or the noise temperature from 27 K t0 8 K.

    Depending on the sidelobe content of the antenna, it may improve a good EME setup somewhat.

    To use real cryogenic cooling requires a lot of special materials and construction techniques to be successful.

    PU2OZT and N5HXR like this.
  10. K6CLS

    K6CLS Ham Member QRZ Page

    The real reason they use cryo cooling as noted above is to reduce the total thermal noise of the receiver system. hams would do best to start with high G/T antennas, which sacrifice some gain for lower thermal noise and reduced side lobes. EMEers certainly do this.

    But it's not atmospheric noise that dominates in VHF UHF and microwaves, these days it is urban QRM and intrusion on our bands! more reason to use trimmed side lobe designs.

    for the OP, please read the ARRL Handbook chapter Space Communications

    Here's VE7BQH's list of yagis, with G/T information:

    N5HXR likes this.

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