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Thread: 40-45 watts on my Alinco DXSR8T ?

  1. #1

    Default 40-45 watts on my Alinco DXSR8T ?

    I've been on hf a number of times this year, from Jan-Jun, and I didn't seem to be getting out of the yard with my signal... and some days I got long distances, Japan and Europe being two locations.

    I realize some of this is propogation.

    So I bought a swr/power meter. And an LDG antenna tuner. My swr is 1.2 to 1.3. I have a 1/4 wave vertical for 80-10 meters. Hustler from DXE.

    Power meter says I'm putting out 35-40 watts on SSB on 15m and 20m. I tuned when I changed frequency.

    I did download the tech manual and found the variable resister on the bottom of the chassis that modifys max power out.

    I now get 40-45 watt out on SSB... into a dummy load and out to the antenna. Thats if I talk loudly.

    Tried FM as a test, got 55 watts. AM got 50 watts.

    According to the manual, I should be getting 100 watts... Is there another adjustment I can check ? Or is this, my setting is high power, correct ? Or should I be getting 100 watts ?

    My only test gear is a multimeter and the power/swr meter.

    Thanks !
    Last edited by N4AAB; Wed 16th Dec 2015 at 02:48. Reason: typos
    --
    73, Jim/N4AAB got my Extra class license on Aug 10, 2017. Vanity call in Oct, 2014.
    My Ham radio site has no popups, no music, no banners.
    'Through the thorns to the stars' from Ghost-in-the-Shell anime.

  2. #2

    Join Date
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    Hello Jim,

    Who manufactures the RF Wattmeter / SWR Bridge ... Name and Model Number?

    Dan
    WA9WVX

  3. #3
    K7KBN's Avatar
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    I agree with Dan: we need the info on what you're using to measure RF power. And what sort of "multimeter" so you have? Can it be trusted as far as accuracy?
    73
    Pat K7KBN
    Semper ubi sub ubi.

  4. #4

    Default

    I didn't use a multimeter to test rf power. I was saying its the only test equipment I have.

    I have two rf/power meters. There are a OPEK SWR-3 and a Diamond SX-200. They give the same results.
    --
    73, Jim/N4AAB got my Extra class license on Aug 10, 2017. Vanity call in Oct, 2014.
    My Ham radio site has no popups, no music, no banners.
    'Through the thorns to the stars' from Ghost-in-the-Shell anime.

  5. #5

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    Jim unless you have a PEP RF power meter, it will not show correct PEP output on SSB. Lets verify your PEP on the dummy load. I suggest using CW to generate the carrier. 1st put the dummy load on the radio and bypass the tuner. Turn the power down to 5 watts and key up in CW mode. You should see about 4 - 5 watts output. Also the swr should be 1:1. If you get that reading then we can continue. Put the radio 25 watts and key up again in CW. You should be seeing 25 watts now. Repeat this at 50, 75 and then 100 watts to confirm the radio is working as advertised. You say this happens on 15 - 10 meters, what about 80 - 40 meters. I suspect your PEP on ssb is closer to 70 -80 watts and am wondering if the radio is folding back due to reflected power.

  6. #6

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    Hello Jim,

    Well I checked the specifications on both RF Wattmeters / SWR Bridges and the Diamond SX-200 is the only RF Wattmeter that is able to read RF Peak Envelope Power for SSB and AM modes and this is the setting you should be using while operating in the Single Side Band mode which is a 50% Duty Cycle. For measuring CW (Morse Code) and FM, the meter should be in the Average RF Wattage setting because it's a 100% Duty Cycle.

    The problem of Low RF Power Output of 45 to 50 Watts may be caused by having the RF meter in the wrong switch setting and/or your Power Supply is NOT providing +13.6 VDC at 20 to 25 Amperes of Current to the transceiver. This is where you would use your Multi-Meter most likely a Digital Volt Meter for measuring the DC Voltage under load to verify the +13.6 VDC is NOT dropping more than .1 VDC otherwise your Power Supply could be folding back / dropping the DC Voltage lower than what is required by the transceiver. At this point I'm ruling out the 50 Ohm RF Dummy Load and LDG Automatic Antenna Tuner as part of the problem since they're providing a 1.2:1 VSWR to the transceiver. One other thing that might be causing the Low RF Power Output on SSB is your Microphone Gain Setting and "IF" this transceiver has a TX Compression Setting Selector. Make sure that the ALC Meter reading does NOT exceed into the maximum range which will automatically reduce the RF Power Output Level.

    Dan
    WA9WVX

  7. #7

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    Power meter says I'm putting out 35-40 watts on SSB on 15m and 20m. I tuned when I changed frequency
    35-40 on average meter should easily be 75- 80 watts PEP. Good idea about the mic gain. I doubt it's the power supply. Jim still needs to do testing 101 and take the radio > power meter > dummy load and test with constant carrier to eliminate any guess work about how the radio is performing. My 2 cents. I find using CW is easiest method for me to test/tune radios.

  8. #8

    Default

    Power supply set at 13.8VDC. Current sits at 1 AMP during receive and climbs up and drops as I speak into the mic on SSB. I tuned the tuner if I changed frequency.

    To test, I did this: mic, radio, swr/pwr meter, then tuner, coax, dummy load.

    When I use FM, I get 55 watts. AM 50 watts. This is on the high wattage setting into a dummy load. I think the radio was set to 20m band, but it was on dummy load.

    SSB I get 35-45 watts. It varies as I talk.

    On the bottom of the chassis, there is a small variable resistor. Whith every thing shut off, andI wait to make sure the power supply capacitors are discharged. I slightly adjust the variable resistor. I got all transmitt types to go up about 5 watts, thats the wattages I've posted.

    After I finished the small, about an eigthth of a turn. I put the radio back in the case. Turned pwr supply on, made sure it was at 13.8 VDC output and tried again.

    Mic held down for FM and AM, the current is steady, 15 amps. SSB amperage varied between zero and 15 amps. This is all into dummy load.

    I tried this process several times. I was able to get the max wattage output to vary slightly, but never over 55 watts.

    The power supply is new and doesn't appear to have any problems. No odd smells, no arcing, no scorches, etc.

    In the spring I'll try it with my gas generator. I want to wait until after the last freeze to use it. I talked about doing this last summer
    with relatives, to check it using a different power source, but too many familial distractions. And I thought I would have more time to do my hobbies upon retirement.

    I did make sure I was using the appropriate setting on the watt meter, button in and out. One position for SSB, and the other for FM/AM.

    The wire from the PSU to the radio is new. I did trim the ends to make sure it wasn't cracked wires inside the insulation casuing a problem.

    I may have to just settle for what it is capable of.
    Last edited by N4AAB; Thu 17th Dec 2015 at 01:51. Reason: info
    --
    73, Jim/N4AAB got my Extra class license on Aug 10, 2017. Vanity call in Oct, 2014.
    My Ham radio site has no popups, no music, no banners.
    'Through the thorns to the stars' from Ghost-in-the-Shell anime.

  9. #9

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    No time until after Christmas, but I'm going to come up with a sequence of tests to check into this more.

    basically; this radio has 3 power settings, I'll try all 3 at the mid freq of the General parts of 20m, 15m, 12m, 10m into a dummy load. Using AM, FM, and SSB, with me talking into the mic and not talking.Tuning each in with the tuner. I'll post the results in this thread.
    --
    73, Jim/N4AAB got my Extra class license on Aug 10, 2017. Vanity call in Oct, 2014.
    My Ham radio site has no popups, no music, no banners.
    'Through the thorns to the stars' from Ghost-in-the-Shell anime.

  10. #10

    Join Date
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    Jim,

    Your test configuration radio, swr/pwr meter, then tuner, coax, dummy load ... is NOT correct.

    This should be radio, swr/pwr meter, coax to 50 Ohm dummy load in your ham shack. If you insert your Automatic Antenna Tuner, you're ADDING RF Losses into the measurements, IF you have ADDITIONAL RF Cable then you'll incur more Losses so the LDG should be out of the circuit completely and you should have a short length 2' to 3' Maximum RF cable between the SWR / RF Wattmeter and the 50 Ohm Dummy Load. Remember you're only testing the RF Output of the transceiver.

    Dan
    WA9WVX

  11. #11

    Default

    Okay I'll try it that way.
    --
    73, Jim/N4AAB got my Extra class license on Aug 10, 2017. Vanity call in Oct, 2014.
    My Ham radio site has no popups, no music, no banners.
    'Through the thorns to the stars' from Ghost-in-the-Shell anime.

  12. #12

    Default Low Power

    Quote Originally Posted by N4AAB View Post
    Okay I'll try it that way.
    I realize, this is an older post, but it seems that there was a lot of info about the RF Watt Meter and no solution to the problem.
    The Alinco SR8T, has a solder jumper on it's main board, when closed it will power limit to 50 Watt.
    Check your manual, it is described there.
    If closed, remove or have someone remove the solder bridge and try again.
    Chances are, if you bought the rig used, that someone had it possibly modified and operated it on some band that is not legal for this radio.
    Make sure, it does not transmit below 28Mhz!
    My two cents.
    Good Luck!

  13. #13

    Default

    It isn't soldered, so I should be at 100 watts. But this is on SSB... my watt meter could be reading that wrong. I have tried on AM, and it reads 100 watts. Also tried into a dummy load, same readings.

    I do have some long coax between the radio, swr/meter, and tuner. 10 foot for one and 25 feet for the other.

    But I have some connectors now and I can make shorter coax runs.

    My brother-in-law and I buried the coax out to the antenna, and I can pick up, but haven't transmitted to, more people during the day. I also have my extra class done and can try those parts of the bands now.
    --
    73, Jim/N4AAB got my Extra class license on Aug 10, 2017. Vanity call in Oct, 2014.
    My Ham radio site has no popups, no music, no banners.
    'Through the thorns to the stars' from Ghost-in-the-Shell anime.

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