Operating AM on 20 Meters

Discussion in 'Amplitude Modulation' started by KC8YLT, Mar 15, 2017.

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  1. W2VW

    W2VW XML Subscriber QRZ Page

    The final would have to be reconfigured for class C with some grid current. Hopefully the driver stage has the necessary heft.

    Sounds like a fun project.

    Alternately, unbalancing the balanced modulator and bypassing the I.F. filter can produce low distortion AM with carrier level about 50% of plate dissipation.

    One big problem is many people won't even complain about the drift when using AM.
     
    AF6LJ likes this.
  2. W2VW

    W2VW XML Subscriber QRZ Page

    Fragile screens? Heck, you can run all the way up to just over 30 mills without breaking the tubes. I have the Tee shirt.
     
    AF6LJ likes this.
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    I'll keep our suggestions in mind.
    I had actually thought this up myself.
    As for cooling a blower bolted to the back of a Sway would do the job.

    This project would start out with the original finals being screen modulated.
    I could be wrong but I see a 6BQ5 doing the dirty work. (in the modulation department)
    Suggestions welcome. :)
     
    KC8YLT likes this.
  4. KC8YLT

    KC8YLT Ham Member QRZ Page

    I hate to own up to this but I have a siltronix 1011c that I made the transmit am only and screen modulated the 8950, I used the radios own 12ax7 mic amp and drove the receive audio tube, I cant think of the number but it uses a triode driving the pentode I believe it was. It sounded good with a shure bros dynamic mic but I had to readjust the bias on the tube and tune the load just rite but it sounded really good. I drove a couple miles up the road and had my girl friend count into the mic so I could here it. No I was not on any ham band while I was doing this. But Sue, you mentioned about the 6bq5. A lot of the old tube type cb radios used that tube as a rf final and another one as a audio modulator. Some of these old tube type cb radios are still easy to find and cheap as well and have most of the parts you may need for your project. I think a swan 350 or 500 would make a great rat rod rig! You would be the first I have seen do it.
     
    AF6LJ likes this.
  5. KD2BRM

    KD2BRM Ham Member QRZ Page

    I do on occasion. 20M always seems to propagate somewhere at anytime of the day. We just need more ops calling on AM to get it going again.
     
    KC8YLT likes this.
  6. K4KYV

    K4KYV Subscriber QRZ Page

    20m is good for one-on-one QSOs, but I never cared for operating in "groups" on that band. Inevitably, at least one member will be inaudible and you end up spending endless minutes listening to dead air and background noise, or SSB QRM.
     
    WA3VJB and KC8YLT like this.
  7. KD2BRM

    KD2BRM Ham Member QRZ Page

    Very True.
     
    KC8YLT likes this.
  8. KM1H

    KM1H Ham Member QRZ Page

    Its when the current is peaked at 10-20 ma and suddenly heads for the pin as the screen heads to the anode.
     
  9. KM1H

    KM1H Ham Member QRZ Page


    The band is good for roundtables when the skip is short and most use a simple dipole or vertical. Im usually at the far Northeast end and can work everyone using a 3 el yagi set at some mid point. Often a 25W carrier is all that is needed but the amp is instant on pair of 3-500Z's.
     
    KC8YLT likes this.
  10. W2VW

    W2VW XML Subscriber QRZ Page

    You mean like when someone forgets to select the correct antenna because they have been up all weekend?
     
    KC8YLT likes this.

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