SSB tuning with a vintage receiver

Discussion in '"Boat Anchor" & Classic Equipment' started by KK4RUT, Nov 24, 2021.

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  1. KK4RUT

    KK4RUT Ham Member QRZ Page

    @SM0AOM THANK YOU! I will definitely give that a shot next time I am looking for SSB.

    I’ve been listening to a lot of AM and CW lately. I just need to get the nack for tuning in SSB.

    Another question I have is, the 75A-1 and the HRO-60 are both set up for twin lead. Specifically the 75A-1 is set up for 300 OHM twin lead. What is the best most efficient way I can use the 50 ohm coax that I have, for the feed line?
     
  2. SM0AOM

    SM0AOM Ham Member QRZ Page

    Most receivers of "yesteryear" were made with input impedances in the order of "a few" hundreds of ohms. However, impedance matching is very uncritical so coax or balanced feedlines of any convenient impedances may be used.

    Just make sure that the antenna coupling link is properly connected to the feedline. Many (most) receivers use a jumper between chassis ground and one side of the link when connected for unbalanced or coax feedlines.

    73/
    Karl-Arne
    SM0AOM
     
  3. N2EY

    N2EY Ham Member QRZ Page

    In many older receivers, "AGC" was called "AVC". Same thing. In some receivers, turning on the BFO automatically turns off the AVC/AGC. Note that the S-meter, if fitted, won't work in most older receivers unless the AGC/AVC is on and the RF Gain is all the way up. That's no big deal.

    And use the RF Gain (also called "Sensitivity" in some receivers.

    Ah....NO.

    Here's what's really going on:

    If you try to receive CW, SSB or even AM with the RF Gain all the way up and the AGC/AVC off, the usual result is too much gain before the second detector, unless the signal is VERY weak. Sometimes just the amplified antenna noise is too much.

    AGC/AVC works by reducing the RF Gain automatically, depending on the incoming signal (or noise) strength. But with AGC/AVC off, that doesn't happen, and you have to do it manually.

    Yep. Of course you'll have to manually adjust the RF Gain for QSB and such, and the S-meter won't work, but those are minor details.

    Also this:

    Many older receivers have quite fast tuning rates (number of kHz per turn of the knob). Using them to receive SSB takes a bit of skill if you're used to the sloooow tuning rates of "modern" radios.

    73 de Jim, N2EY
     
  4. KK6IYM

    KK6IYM Ham Member QRZ Page

    Yes, you can use the BFO frequency adjustment to slightly tune the radio for final "dialing in." The radio dial and the BFO work together. Sometimes the adjustment is easier with the BFO when the dial is too sensitive to slight movement. As others have said, it is a radio by radio determination what works best.

    Norm
     
    KK4RUT likes this.
  5. KK4RUT

    KK4RUT Ham Member QRZ Page

    So here is another good question I have always had! How would I give a signal report for CW or SSB if the S-meter only works with the AGC on? And for most if not all the ones I’ve ever seen the AGC only works for AM.
     
  6. KP4SX

    KP4SX Premium Subscriber QRZ Page

    You don't use an S-meter for signal reports.
     
    K1APJ, WA1GXC and N2EY like this.
  7. WA1GXC

    WA1GXC Ham Member QRZ Page

    Common question...Someone here on the CW forum asked just within the last week. Unfortunately, many hams (and not just newer ones) incorrectly
    believe the S-Meter to be the foundation of all that is authoritative . The S-Meter is to correct signal reports as The Internet is to human wisdom.

    The R-S/ R-S-T system, it can be argued, is slightly subjective...But by that characterization, it means it's correct. You're the operator and your perception of
    the signal is therefore by definition 100% correct.

    https://www.arrl.org/files/file/Public Service/fsd220.pdf

    S-Meter is a somewhat useful feature for comparing antenna performance, "A" vs. "B", rough alignment indications during maintenance --
    but other than that, really experienced operators consider it of little to no value whatsoever.

    You're the radio operator. Not your radio.

    73
     
    Last edited: Nov 26, 2021
    K1APJ likes this.
  8. SM0AOM

    SM0AOM Ham Member QRZ Page

    Exactly.

    The RS(T) system is derived from a viewpoint that has passed its "sell by date" by a long time.

    Professionals use the QSA/QRK scale between 1 to 5 and in more practical terms a three-level scale would be perfectly adequate for amateur radio purposes with "1" meaning "readable with difficulty", "2" = "clearly readable" and "3" = "armchair copy" or "full quieting".

    "S-meter reports" have become completely irrelevant, especially in the present day noise environment on HF. Sometimes I hear people on "80 m SSB" complaining about their noise level, which they describe as "I have a noise level of 59".

    There is a very good reason for why professional gear lacks "S-meters".

    73/
    Karl-Arne
    SM0AOM
     
    K1APJ likes this.
  9. KI4ZNV

    KI4ZNV Ham Member QRZ Page

    Because everyone is 5-9?
    --scott
     
  10. K0IZ

    K0IZ Ham Member QRZ Page

    HRO 60 is a great receiver but no product detector, which didn't come along until some years later. Made SSB sound much better, also allowed use of AVC/AGC and S-meter.

    The HRO 60 has a NBFM socket (for a NBFM adapter that no one uses). QST had a couple of product detector adapter articles (4/66 and 12/68). Device plugged into NBFM socket. CQ and 73 also had articles. Maybe simplest uses just a 6J6. http://emmittsfixitshop.com/Projects_product_detector.html. Worth trying.
     
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