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Modern radios

Discussion in 'Amplitude Modulation' started by N2DTS, Nov 21, 2019.

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  1. N2DTS

    N2DTS Ham Member QRZ Page

    Yes, I think you can get it fairly wide on RX although I do not know what the low frequency limit is.
    On the transmit side, they often limit the bandwidth to 3 or 4 Khz , besides the passband filter.

    I have heard the K3 on the air and they sound fine. I have not heard of anyone running one for a while though.
    The KX2 and KX3 I had sounded ok, maybe 100 to 3500 Hz but the KX2 had issues with power control on AM.


     
  2. K5UJ

    K5UJ Ham Member QRZ Page

    Do you have a SDR rig? When it craps out can you repair it?
     
  3. K3XR

    K3XR Ham Member QRZ Page

    I have received very good reports using the Ten Tec Orion II on AM. This is followed by an Ameritron ALS 1300 with around 250 watts of carrier.

    You do the best you can with the equipment available. While it sounds great not everyone can produce a signal with "broadcast quality" audio.
     
  4. KF5LJW

    KF5LJW Ham Member QRZ Page

    Yes I do, 3 of them.

    Only if the component is discreet and easy to remove/replace, and available. However like any modern radio today is not serviceable by a bench technician other than the factory. So that argument is not valid as any new modern radio today has to be returned to the factory for repair. Like a cell phone, you can't fix it. Only simple repairs. Now calibration and optimization is like most any other radio.

    Go over to the commercial side of radio, and SDR has already taken over. As A/D converters continue to come down, Most all new radios in the near future are going to be SDR.
     
  5. AG5CK

    AG5CK Ham Member QRZ Page

    I consider my sdr an expensive component. I built and can maintain the PC it needs to operate.

    By the time the sdr craps out the parts will likely be obsolete and unobtainable. Then it's time for an upgrade. I'm ok with that.
     
  6. K5UJ

    K5UJ Ham Member QRZ Page

    How much transient voltage can they handle at their antenna feedline jacks? If you tx 1 watt @ 50 ohms into them directly will they be okay?
     
  7. KF5LJW

    KF5LJW Ham Member QRZ Page

    Well if you are talking about an SDR HF Transceiver like a Flex, Icom, or Yaesu has built in protection for the RX like any transceiver. I do have have what I would call toy SDR RX only radios, SDR Play RSP2pro and Airspy HF+. There are several after market protection modules you can purchase or even build yourself with a couple of diodes. Lots of ways to skin that cat, and not unique to SDR radios but any conventional receiver.

    Example I just finished building a Active Small Loop Antenna using an INA02186 LNA. It has protection built-in the Pre-Amp. Nothing to it but two SMD diodes across the input. When I transmit the waterfall and spectrum white out, but no harm.
     
  8. N2DTS

    N2DTS Ham Member QRZ Page

    I have repaired my handheld R928 plus twice.
    Once the power input jack that disconnects the battery when you plug in the power supply
    failed and I repaired it.
    I also replaced the tuning encoder with one without detents, I also replaced the output devices after transmitting into nothing a few times.

    In many cases, the diagram is on the web.

    Its not an sdr, but I have done a lot of mods to the Nouveau 75 which is all surface mount components.

    Sorry, but the way things are these days, you will not be able to replace the electronics in ANYTHING you have bought in the last 10 years
    50 years from now. Or 20 years from now.

    How long do you think you are going to be able to get all the high power vacuum tubes you might want?

    Parts expire, so does software and programs that run on it.
     
    KA0HCP likes this.
  9. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    I use my Ten Tec Jupiter on AM occasionally, and it does do a great job on AM...and that's not just objective opinion....the trapezoidal waveform is perfect...far more linear than any heavy iron AM rigs I've used...and I've used quite a few.
     
    WD4IGX likes this.
  10. N2DTS

    N2DTS Ham Member QRZ Page

    That is the second Jupiter recomendation.
    What does the audio passband go out to?

    I had an Argonaut 5 that did ok on AM but it put out a lot of trash on frequency, phase noise or mixing noise or something.
    Remember when TenTec used to hate AM and would not put it on their rigs?
     

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