AM QRP

Discussion in 'Amplitude Modulation' started by AC0OB, Oct 15, 2019.

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  1. K5UJ

    K5UJ Ham Member QRZ Page

    Be sure to use a horizontal dipole 20 feet off the ground, or an inverted L with no radials; get pissed off when you get a crappy signal report. Go off in a sputtering distorted rant with 15% copy at the other end of the QSO.....
     
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  2. W8KHK

    W8KHK Ham Member QRZ Page

    My comment about long transmissions during QSB was just intended as a bit of light humor. Actually, the rig should be fun for short haul communications in the neighborhood, etc. Another use I have is to feed it with my audio processor, into a dummy load, then I will be able to analyze the audio bandwidth, etc, on the SDR. As stated elsewhere, some folks check into nets regularly with this little rig, feeding an amplifier so they can be heard.

    It is pretty amazing to find a kit with three pole crystal filter IF superhet, with Class-H modulation and Class-E final, in such a little box, for only $100. Having all the SMD pre-soldered is a plus!

    Another thing I was thinking of when I ordered it... Use it as an (unmodulated) RF source for a Viker or Dixie-100 in transceive mode - always correctly zero-beat. Just need to add sequencing and a couple relays, should be a fun receiver and VFO for this configuration.

    By the way, you know you are piss weak when you hear "you are five by nine here in Podunk Valley, would you please repeat your name and call, preferably with standard phonetics?".
     
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  3. AC0OB

    AC0OB Subscriber QRZ Page


    Haha. I dunno, :)I have had some late night discussions with Timtron and others when they were rock solid into the midwest and sometimes our monologues lasted 30 minutes. Since I was using the Henry 2K-4 and feeding it from the Knight T-150, I would look over at the Henry and could see the 3-500Z's had undoubtedly de-gassed sufficiently.:eek:


    Pheel
     
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  4. K3XR

    K3XR Ham Member QRZ Page

    Is based, or at least inspired by, the Dave Benson, K1SWL Retro 75. Have not fired it up for a couple of years but it's a fun little rig.

    [​IMG]
     
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  5. W2NBC

    W2NBC Ham Member QRZ Page

    Thanks for the link and I’ve ordered one!

    If you all think about it, not many “AM” transceivers were commercially produced. The Gonset G-76, the “Retro-75”, and... ?? Anyone?

    I think building a kit for an AM transceiver in 2019 is fantastic, no matter how piss weak ..

    “can you hear me now?”
     
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  6. N2DTS

    N2DTS Ham Member QRZ Page

    Looking at the diagram, the RX audio might need tweaks as well.

    The retro 75 was fun to build and modify, it was very basic but people made contacts with them.
    There is lots of QRP on the bands, if you don't like it, tune elsewhere or ignore weak signals.
    I have had some very nice qrp to qrp qso's with SOTA (Summits On The Air) guys with my KX2 at 10 watts pep, solid QSO's,
    on AM and ssb, and the usual suspects on 3885 also reported a good copy/signal with 2 watts carrier.

    There seems to be a big jump around 25 to 40 watts, above that, lots more power does not seem to buy as much as you would expect.
    I can vary the output of the screen modulated rigs easy and between 100 watts and 400 carrier is about 1 S unit mostly reported.
    Hardly seems worth it.
     
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  7. N2DTS

    N2DTS Ham Member QRZ Page

    Got the radio today and built it.
    It took about 2 hours.

    Seems to work very well.


    [​IMG]

    [​IMG]

    Filter in the 10 Khz so it transmits out to at least 5000 cycles.
    Modulates 100% no problem, the hand mic sounds a bit poor, as expected.
    The receive is not sdr sharp but it sounds quite good (in headphones).
    The built in speaker is not real bad.

    Had a qso to Georga where I was S9 and solid copy with very good audio reports.
    The watt meter reads around 3 watts carrier...
     
    Last edited: Oct 20, 2019
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  8. W2VW

    W2VW Ham Member QRZ Page

    Gonset G-28, Laffin Idiot HA-410, HA-460 and a few others but I believe you were thinking in terms of all classic HF bands.

    And don't forget the Cobra-29.
     
  9. N2DTS

    N2DTS Ham Member QRZ Page

    If you build one of these, make sure the heat sinks are well above the board.
    If not, they can contact some surface mount parts, keep them up off the board.

    My radio is stuck in semi transmit, not sure if it had anything to do with that or something else went.
    It worked well for a while, then it would stick in TX and I would have to power cycle it.
    After a few times of that it is stuck in TX.
    Before that happened, I noticed it put out more power lower in the band, so I took one turn off the output toroids, I think I had one extra
    turn on each, power went up to 5 watts out.
    I guess its like other kits, one pass of wire through the core is one turn, even on the first pass.

    By the way, nothing in the radio gets hot, or even warm, so old buzzard transmissions are ok.

    I will order another one, its quite a neat radio that works very well.
     
  10. K5UJ

    K5UJ Ham Member QRZ Page

    Yeah--make my day. :rolleyes:
     

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