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Alternative methods to measure output power

Discussion in 'General Technical Questions and Answers' started by KK6JGJ, Jul 16, 2021.

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  1. KK6JGJ

    KK6JGJ Ham Member QRZ Page

    I have an MFJ-849 Digital SWR/Watt Meter and a MFJ-904H Antenna tuner; Both of these in series or separately are having trouble picking up any signal coming out of my Kenwood TS-480Sat. I have tried phone and Digital, they seem to transmit from at least radio perspective but no power is outputting onto the meter displays of either the wattmeter or the antenna tuner. I have transmitted from Kenwood and it is not picked up on the ICOM7300; This I think is reasonable assumption that I am getting no power out.

    I was also getting same issue on the Icom but in this case it was showing lower power out.

    I have tested with different antennas (3x) and different feedlines to those antennas.

    I have tested the DC power out of power supply and it is fine.

    Any other ideas to confirm that the Kenwood is not amplifying properly?
  2. W7HV

    W7HV Ham Member QRZ Page

    Put it into a dummy and look at the voltage across the dummy with an o-scope or RF probe and dvm.
    KI4ZUQ likes this.
  3. K6CLS

    K6CLS Ham Member QRZ Page

    What mode are you using to transmit? Do not use LSB or USB, use FM, or CW if you have a key.

    Set the TS480 meter to PO mode. What does it read? Double check the radio PWR setting.
    WB5THT likes this.
  4. N8YQM

    N8YQM Ham Member QRZ Page

    Agreed on using CW. If you just key the microphone in LSB or USB you won't see anything unless you're speaking into it and your mic gain is high enough. If you don't have a CW key, go to menu 48 and set it for option 67 to enable the pf key to put out a 10 watt carrier (TX tune feature). That would at least tell you if the transmitter is working.
  5. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    Use a mode that provides Carrier with NO Modulation. CW, FM, RTTY. Key the mic or close the morse key. Alternatively rig up a Plug and SPST, Single Pole, Single Throw, Switch to substitute for the morse key.
  6. KK6JGJ

    KK6JGJ Ham Member QRZ Page

    Sorry left that detail out I also tried a dummy load inline to the above tests in place of antenna in Meter->Antenna and also put it right on the line from radio to dummy. All of them showed no power out on meters.

    I do not have an O-scope or DVM to RF probe (don't have the probe, nor is the meter have the range if looking at freq
  7. KX4OM

    KX4OM Ham Member QRZ Page

    Has it always acted like this with the TS480S and the ICOM-7300? Is the dummy load part of the MFJ-904H Antenna tuner?

    I suggest:

    1) Disconnect everything from the transceiver's RF output jack.
    2) Connect the transceiver's RF output to the MFJ-849, "TX" connector.
    3) Connect the MFJ-849 "ANT" connector to the dummy load.
    4) Turn on the transceiver.
    5) Turn on the MFJ-849.
    6) Follow the instructions in post #4 by KA0HCP.

    If the problem still exists, your problem may due to:

    1) Bad cable #1
    2) Bad cable #2
    3) Bad Dummy load
    4) Bad MFJ-849
    5) Two bad transceivers

    Ted, KX4OM
    Last edited: Jul 16, 2021
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If the IC-7300 receiver works and it doesn't pick up the signal from your Kenwood tuned to the same frequency, I'd say it's a reasonable assumption the Kenwood's transmitter isn't working at all, not even a tiny little bit.

    Even if the Kenwood's power amplifier is completely "dead" as a doornail, the Icom should still pick up its signal just fine. I can turn my power down to "zero" with any transmitter I have and every one still generates a strong signal to be heard by a receiver tuned to the right frequency: Whether using an antenna, or a dummy load.

    If the Kenwood output stage (power amplifier) is working, that should overload the Icom's receiver, even though they're not connected in any way. Just being in the same room will do that.
  9. KK6JGJ

    KK6JGJ Ham Member QRZ Page

    Thanks for suggestions so far. I used this method as well as CW before it to get a reading on the radios power meter it thinks it was sending High SWR into dummy load and radio power was high at 100W on CW it sent about 5W per radio meter. In either configuration of CW or tone through PF the radio meter showed the same reading but neither meter on the watt meter or antenna tuner had 0 display/gauges moving.
  10. KK6JGJ

    KK6JGJ Ham Member QRZ Page

    Previously I was using both Phone and Digital so figured digital would be a variety of power fluctuations that is what the meter showed while hooked upto IC7300 on dummy load and antenna

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