Kenwood 530S No ALC

Discussion in '"Boat Anchor" & Classic Equipment' started by KI5BOM, Sep 10, 2018.

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  1. KI5BOM

    KI5BOM Ham Member QRZ Page

    I am a new ham, tech, waiting on my call sign, but I have picked up a 530c with good rec, but no ALC. Looks like the hv caps have bee replaced as well as cathode resisters. Bias is good at 60v. Looking for an Elmer to try an get it all sorted out. Thanks.
     
  2. K7TRF

    K7TRF Premium Subscriber QRZ Page

    If you can't peak the ALC while keying the rig in Tune or CW mode then you don't have drive into your final tubes. Having good cathode resistors and HV caps is good in terms of final stage output power, but lack of ALC reading indicates lack of drive INTO the finals stage, not issues with finals stage itself.

    The common culprit for lack of drive into the finals is the 12BY7A driver tube but it could also be other things such as poor IF or RF board alignment or any of a number of things that could lead to the drive or TIF signals not reaching the driver tube. Can you get an ALC peak on any band? There's typically a lot of drive power on 20 meters so that's a good band to start with when testing for drive signal.

    And are you certain you're actually keying the rig when you test for ALC? IOW, have you either unplugged the CW key to take advantage of the shorting key jack or have plugged in and closed the key contacts while flipping the SEND switch in Tune or CW mode? Have you been able to successfully set the finals bias as explained in the manual? The bias isn't directly relevant to drive level and ALC metering problems but it indicates that the rig is actually switching into transmit mode properly.
     
    N2EY likes this.
  3. KB4QAA

    KB4QAA XML Subscriber QRZ Page

    -Cleaned the Meter select switch?
     
  4. N8YX

    N8YX Ham Member QRZ Page

    Screen Grid switch "On"?
     
  5. KI5BOM

    KI5BOM Ham Member QRZ Page

    Thanks so much for the reply. I know this is an old rig, but I want to be able to understand the different components of the radio. Dont really want to send it off for repairs or be just an operator. I want to "learn" how transceivers work. I don't think this is a complicated radio from what I can gather.

    I can change the bias without any issues as directed in the manual . The driver tube does light, but guess that doesn't really mean much. I cant move the ALC meter in any band. I can hear the switch clicking the the meter actually sort of jumps to the left a bit. I have tried to tune in "tune" position and the cw no keyer. Have not tried SSB, but doubt it would make any difference.

    What I did notice that may help in the diagnosis, when I first got rig while tuning for the first time following the manual instruction on tuning, the meter pegged to the right in ALC mode and I thought I saw a faint spark inside the radio. Thats when I removed top and started looking for burned components. I saw the HV caps had been replaced. Measured 900v. Did a bit of searching on the net and check the cathode resisters, looks like they were replaced.(soldering not too good but measure to spec).

    If the ALC will not move without a good drive, I think the easiest thing to do, it start by changing out the driver as it isnt' very expensive. I only have a VOM so trouble shooting is limited.

    I have asked around locally, but most everyone is a 2m guy or has high end HF radio. Thanks again guys.
     
  6. N8YX

    N8YX Ham Member QRZ Page

    Best thing to do:

    Join the Yahoo Groups Kenwood Hybrid reflector and post your questions/comments there. The "faint spark inside the radio" comment is a bit disconcerting and is probably going to require a bit of inspection to determine what's up. If you were local to me I'd have you bring the rig over and we'd troubleshoot it on my bench.
     
    K0OKS and K9ASE like this.
  7. G3YRO

    G3YRO Ham Member QRZ Page

    Forget looking at ALC (for now) as that only shows you excess drive . . .

    Instead, keep monitoring PA current . . . presumably you can see the Standing Current OK (as you said you set the Bias).

    What happens when you transmit in the Tune position with some Carrier, and resonate the Pre-selector control (what Kenwood label "Drive") . . . can you see an increase in PA current?

    Roger G3YRO
     
    Last edited: Sep 11, 2018
  8. K0OKS

    K0OKS Ham Member QRZ Page

    Roger, I think he means he can’t complete the first step of the tuning process, which is to peak the ALC indicator, essentially setting the “Drive” (preselector).

    I would start with a good cleaning of all the bandswitches and careful lubrication of them with something like DeOxit or CrC-26 applied with a toothpick or similar... don’t get any cleaner all over the switch wafers.

    Then replace the driver tube as mentioned above. If that fails, consult the Kenwood Hybrid Group.

    Welcome to the hobby. You are going to end up loving that rig once you get it going. I still run a TS-820S as one of my regular rigs.
     
  9. G3YRO

    G3YRO Ham Member QRZ Page

    I realise that . . . but he may have SOME Drive, just not enough to reach the point of generating any ALC.

    By getting him to do what I suggested, I was trying to determine that . . . ie is he just LOW on Drive (meaning a bit of re-alignment needed) . . . or does he have none at all (so a complete fault) ?

    Roger G3YRO
     
  10. K5DH

    K5DH Ham Member QRZ Page

    The Kenwood hybrid rigs are prone to suffering from dirty switch contacts, especially on the band switch wafers. It would be worthwhile to procure some DeOxit D5 and clean all of the radio's switches and pots. Even if this doesn't cure the drive issue, it's still a very necessary thing to keep the radio running properly. Also, go around the radio and tighten all of the hardware. These rigs have been known to have grounding issues from loose hardware and corrosion at CCA ground points.
     
    VK6APZ and K0OKS like this.

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