Early Adjustments

WSTM (and KD2SL!) TowerWe’re already up to day 5 of operation for the 6m repeater.  I’ve enjoyed meeting some new hams, and reconnecting with some old friends!  Possibly this weekend some additional new users will arrive, as people have time to set up antennas, program their radios, and join in.  If you haven’t tried it yet, I encourage you to drop in with your call sign and see who is around.  If you’ve tried to get in and can’t, I’d like to know that too; e-mail me at kd2sl@yahoo.com.

For a “new” repeater, constructed out of “old” parts, it is doing very well.  A few minor adjustments have been made.  First, the CW ID was too loud, so I dropped it down a little, and raised the pitch.  I also lowered the level of the courtesy beep.  Some radio and speaker combinations give a lot of boost to those frequencies, so this should help. 

Second, each time I visit the repeater site, I turn the squelch knob just a smidge.  You might think that you would want to adjust the squelch to be “right on the edge,” so that ANY signal can open it, and let the tone decoder weed out the noise.  However, the tone decoder does an amazing job of sensing tone even when the signal is VERY noisy.  It doesn’t do anyone any good to have the squelch opening on super-noisy signals.  It annoys repeater listeners, and the person who transmitted the noisy signal hears a courtesy beep and thinks (falsely) that they can be heard on the repeater.  I will keep adjusting the squelch VERRRRRRRY slowly until I reach the point where it generally blocks unreadable signals, and lets noisy but readable signals through.

Finally, I have been investigating the source of some intermittent noise, which is sometimes heard on received signals (that is, not during IDs, announcements, or hang time).  On the very first day I noticed that wiggling the coax to the receiver input would make noise.  It was actually two cables: a longer 1/4″ Heliax from the duplexer, which mated to a short pigtail that plugs into the receiver.  Replacing the pigtail didn’t fix it, so made a single new cable that replaced both of the old ones.  My impression is that it helped, but there may yet be more noise generators at work.  We’ll have to see what happens on the first windy day, because ANY loose joint, or loose hardware ANYWHERE on the tower (even if not part of our antenna and feedline) could cause micro-arcing and RF noise generation.  Grounding of the repeater is not complete either, so THAT might be a factor.

Someone suggested that a preamp might help with the weak signals.  It might.  I am sure I will try it at some point.  My biggest concern with that is the VERY strong signals our antenna picks up from TV channels 24 and 25, and FM stations at 94.5 and 107.9.  We do not have a bandpass filter, so a LOT of energy at those frequencies would reach the preamp and possibly overload it.  I suppose I could ADD a bandpass filter at the cost of another 1 dB or so of signal prior to the preamp.  We’ll put this on the list for future experimentation.

In the next post, I’ll get back to a discussion of the duplexer construction.

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About kd2sl

I'm a lifelong geek, interested in anything electronic, but especially ham radio, radio and TV broadcasting, and computers. Employed as a television engineer for several Syracuse, NY TV stations.
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4 Responses to Early Adjustments

  1. n2stc says:

    Hi Kevin et al,
    Nice job on the repeater? I am with you: If it ain’t broke, don’t break it! I would vote against a preamp. You wouldn’t want stations to open the squelch, who can’t hear it. Just my humble opinion. I’m sure someone will set me straight. 🙂
    73, S

  2. Rick Hatalski says:

    Kevin, I have been reading all the great stuff about your TV Ch 3 to 6 meter antenna conversion.
    I find it very intersting. After reading, two questions come to mind. How do you overcome the SWR problem with the analog TV ant resonated to 60-66 mhz, to the lower frequency of 53.67 MHZ?
    Or is the ch 3 TV antenna that broadband? And second, I myself find the DB loss from vert to horiz.
    like 5 to 10 DB.Case in point, On the Mt. Mitchel 6 meter repeator, 53.19 in the N.C. mountians elevation 6600 Ft., with a large wide spaced 6 element yagi pointed at the repeator from about 150 miles away, my Ringo vert receives the signal 2 to 4 s-meter units better over the big yagi. I realize the extreame height of the antenna might overcome the huge loss. Job well done, and I can’t wait to check in with you with my big horiz yagi this June from my home at Lake Murray, South Carolina, Grid Sq. EM-94. Best 73, Rick ND4Z
    BTW…My brother in law lives in the town of Fabius and my former QTH was at the top of Onondaga Hill and later to Erieville, N.Y.

    • kd2sl says:

      Hi Rick,

      The nice thing about batwing antennas is that they are very broadband. The SWR at 53.67 MHz is unreadable on my meter. Regarding polarity, our experience has been similar. The batwing works fabulously for base stations with horizontal antennas, but the range for vertical stations and mobiles is considerably less – although still as good as an average 2m repeater. Thanks for your comments, and I look forward to hearing you on the repeater!

      73 – KD2SL

  3. Andy says:

    Kevin, nice job documenting your project! Looks fantastic! I am hoping you can hear me someday soon!

    I think I am the only one who can’t access the repeater even when I am in downtown Syracuse. I am running kenwood Tk-690 commercial gear. I talked to you at the Rochester hamfest and you traded me some dough and a t-shirt for a TK-6110.

    At first I thought programming issue with my OST. But I verified it is fine, and even programmed your tone into the 53.67 channel. It is strange in that I can access every other 6 meter repeater but yours? I have 2 of these in different cars and have solid signal from the repeater so I don’t believe its the horizontal polarization like some have told me. I am going to check my PL deviation when I have a chance. I usually run 600 hz deviation on the PL FYI.

    http://www.repeater-builder.com/tech-info/pldeviation.html

    Maybe your IF alignment / Discriminator might need to be rechecked? Are you using the standard GE PL decoder? I just find it odd that only your repeater doesn’t decode my PL.

    Andy

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