Kenwood TS-130S Transmit and receive Issues

Discussion in 'General Technical Questions and Answers' started by KM6FXL, Apr 8, 2020.

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  1. KM6FXL

    KM6FXL Ham Member QRZ Page

    Hi all, I recently bought a Kenwood TS-130S, and figured now that I'm home I can get on the air. I am using a Uniden 4 pin mic which I wired as best I could according to the manual and what I've read on the internet. When following the manual's instructions for transmitting (Switch set to "SEND"), my wattmeter/ dummy load reads 0W output on both peak and average readings. When the switch is set to receive and I key the mic, the meter reads anywhere from 30W to >100W peak depending on where the mic gain knob is set. However, the meter reads 0W average, suggesting my voice is not being modulated at all. Another issue is the receive audio. The speaker works, and I know this because sometimes when I hold the PTT the speaker plays static. There is a faint static at all other times, and I'm not exactly sure what settings bring about the sound when the mic is keyed. This only occurs with switch set to receive, and keep in mind I currently don't have an antenna set up to test reception of actual stations.

    Are these symptoms of an improperly wired microphone? Or did I buy a dud? If a video would help troubleshoot please let me know.

  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    That part makes sense. The microphone you wired up most likely only connects audio to the rig when the PTT button is pressed. The rig's SEND switch and the PTT line are in parallel with one another so they're basically the same thing as far as keying the rig is concerned but if your microphone's internal wiring is such that the microphone element isn't connected to the rig's audio input unless you press the PTT button on the microphone (which is typical for many microphones) then just flipping the SEND switch won't deliver audio to the rig. Flipping the SEND switch works if and only if the mic you're using delivers audio at all times or IOW supports VOX operation where you don't need to press the PTT button to connect the microphone element.

    This part is harder to understand and may be a misunderstanding of how SSB power is measured or may be an issue with your rig. First if you keep speaking into the microphone SSB power displayed on a typical average reading power meter should be roughly 25% to 35% of Peak Envelope Power (PEP) depending on voice characteristics and things like whether there's speech compression in use. So when speaking into the mic of a typical 100 watt SSB rig an external average reading power meter will swing up to around 30 watts or so but most of the time will show even less power. If that's what you're seeing then that's normal operation for SSB which unlike AM or CW does not have a constant carrier component. Similarly if you key a SSB rig and do not speak into it you'll see zero watts again because there's no carrier where with AM you might see 25 watts constantly when not speaking and with CW you'd see the full 100 watts.

    If you have an active peak reading power meter, with emphasis on 'active' meaning it has active peak hold circuitry then when in peak reading mode you'd see the full 100 watts as soon as even a short voice peak hit that level but again if you switched back to average mode you'd only see the meter swing up to 30 watts or so on the louder voice peaks and be below that most of the time.

    In terms of setting the mic gain control the key thing is to set the meter to ALC mode and adjust the mic gain so only the loudest voice peaks move the ALC meter towards the top of the ALC range (which is less than full meter swing and marked on the meter). The ALC meter only begins to move when you get up within a few watts of total transmit power so if you see ALC meter movement your SSB PEP is already up very close to maximum power. IOW, the ALC meter is effectively a peak reading power meter as it only begins to move when you're up within about 5 watts of maximum transmit power and by the time it swings to the top of the ALC range you're hitting the rig's rated peak output power. Adjusting for more ALC swing just makes your voice distorted and leads to splatter on adjacent frequencies so set the mic gain in your normal on the air voice by watching the ALC meter.

    Maybe you're doing all of that and things aren't behaving as they should. If so then yeah maybe your rig has some issues. I had a TS-120S that I ran mobile for a while and sometimes it would work fine and then sometimes I'd key the mic and the ALC meter would peg and when I had an SWR meter connected the SWR would suddenly go sky high. I thought it was mobile antenna problems at first but finally put the rig on the test bench and was able to reproduce the problem. The rig was breaking into oscillations somewhat randomly. The solution turned out to be pretty simple which was just loosening and then firmly re-tightening all the brass PCB mounting screws. Kenwood used those screws and the brass PCB standoffs to complete the ground circuitry on those early circuit boards and if they get a bit oxidized you can get funky ground connections that can cause all kinds of gremlins. In my TS-120S about five minutes with a screwdriver just loosening and re-tightening those PCB screws (not adjusting any actual circuitry) tamed the oscillations and I ran the rig for several more years before passing it on to another ham.

    So are you adjusting mic gain for proper ALC action (just hitting the top of the ALC range on voice peaks?) and can you make that adjustment or are things too erratic to do that?
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I don't completely understand the problem, but without an antenna there's no way to know if the rig is actually working.

    You're not far from Pat WA6MHZ who might be able to help you, although the "social distancing" thing makes that a bit more difficult today.

    TS-130S is a very old rig, but was a "good" rig when it was new. Unfortunately that was also 40 years ago. Today, they're not worth much.

    How much would you pay for a 40 year-old computer?:)
  4. KM6FXL

    KM6FXL Ham Member QRZ Page

    I should clarify, when I have the rig set to "send", I also press the PTT before talking. I was unable to get the ALC meter to move at all on send, although on receive when I key the mic the meter pegs.
    While reading your responses, I dropped the microphone, which got both the ALC meter and wattmeter to read signals. Fiddling the wires and mic connector had a similar effect. I am going to spend tonight opening up the radio and checking the mic connector on both the rig and microphone. Thank you for your help, if this doesn't work out I'll let you know.
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yeah, that sounds like an intermittent somewhere in either the mic's connector or the matching connector on the rig with the mic being more likely.
  6. W4HWD

    W4HWD Platinum Subscriber Platinum Subscriber QRZ Page

    The problem is it's a Kenwood 130. Mine was deaf when it was only 10 years old but it did talk.
  7. N8YX

    N8YX Ham Member QRZ Page

    Seen the vintage computer market lately?

    Yes, some are fetching decent sums of money.
  8. KM6FXL

    KM6FXL Ham Member QRZ Page

    I've been spending a bit of time tearing the radio down, found a couple of broken components. I somewhat doubt they are the cause of my issues but I plan to do a complete disassembly and try to get it working properly. I don't exactly need this radio so if anything it should be a good learning experience. Hopefully I'll be able to update with good news in a day or so. Thanks for all who gave advice.

    P.S. I know it's old but it's much cheaper than a new rig. Unless it ends up as a paperweight of course.
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If you don't need it but learn from it, that surely has value.

    Never give up!:)
  10. N7RPR

    N7RPR Ham Member QRZ Page

    Had similar problems with my 130; contacts on the T/R relays had oxidized. Popped the covers on the relays, cleaned the contacts and all was well.

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