Extending Autek WM-1 SWR Meter Question

Discussion in 'Mobile Radio Systems' started by WQ6N, Jan 2, 2018.

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  1. WQ6N

    WQ6N XML Subscriber QRZ Page

    I was wondering if anyone has extended the Autek WM-1 SWR meter for use in mobile? I have one of these and have used in for many years. I am now looking at mounting the sensor in the car trunk between the amp and antenna with the meter movement up in the front. Keeping the eyes on the road is a good thing.

    In addition, this is a non-lighted meter and would like to add back lighting LEDs if possible.

    Thank you in advance.
     
  2. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    The added length will have a slight effect on the reading of course, but as long as you do the job neatly, you shouldn't have any issues. I can't comment on the back lighting, because I've never had one apart. I suspect it isn't difficult, but finding a place for such a large meter isn't going to be easy. So my question is, why do you need an SWR meter when one is built into the transceiver? And, if you're using a screwdriver antenna, what you really need is an automatic tuner.
     
  3. KS2G

    KS2G Subscriber QRZ Page

    In the lighted version of the WM-1, the illumination bulbs are inside the meters.

    The instruction sheet for that version notes: "...there is no retrofit kit available for older, unlighted WM1's. The meters come to us from the meter manufacturer with the bulbs installed."

    The instruction sheet explains that the two bulbs in each meter are "...12 volt bulbs connected in series ... so that each operates at a very low voltage."

    It does not specify what that voltage is, or explain where it comes from.

    Autek (now out of business for several years) provided a schematic for the remote-head, but never the "body" of the meter.
     
  4. WQ6N

    WQ6N XML Subscriber QRZ Page

    Well, I might tap off the power LED and will take a look at the meter face real-estate for a couple of small blue or white LED's (e.g. ebay: 0402 SMD Pre-soldered micro litz wired LED leads resistor 20cm 8-15V Model DIY). I could get fancy and add a photoelectric switch.

    Alan, you are right on all accounts. I do have fully operational Turbo Tuner 2 that works perfectly. The screwdriver shunt is matched and it all looks good. I was trying to see what the power out at various exciter power percentages mainly at 20, 30 and 40 % on different bands from the IC-7100. I am going to agree with most of the reviews that the ALS-500M current meter is not very good. The SWR meter was sitting on the shelf and I decided to put it to work for me while I am learning the characteristics of the setup.

    The cable from the remote head looks to be 3 conductor shielded (estimating target length will be about 20ft):
    5V
    Forward
    Reverse
    Shield Ground
     
  5. K0BG

    K0BG Platinum Subscriber Platinum Subscriber QRZ Page

    In order to "find" the knee in the linear response, you're going to need TWO know-good wattmeters. Or, a decent O-scope with RF detector probes.
     

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