Tuesday, March 24, 2020

Monitoring 10m FM

With all of the activity lately on 10m I decided to see if my Flex was capable of that mode. I honestly didn't know because the band has been mostly dormant for the entire time I've had the rig and I've not had a reason to check.

To my surprise, not only will the F6000-series rigs operate on FM, they also allow all necessary parameters to be configured to allow operation via 10m repeaters.

As soon as FM is selected as the mode, a menu opens that allows setting the desired offset, offset direction, squelch level and CTCSS tone frequency.

Repeaters on 10m use a -100 kHz offset and usually operate on input frequencies (rx freq for you/me, the users) of:

29.620
29.640
29.660
29.680

Unfortunately, I was not able to key up any repeaters on any of those frequencies. That may be due to poor propagation at the moment or because 10m repeater operators have discontinued the use of their repeaters due to inactivity.

One of my most bizarre QSO's ever (25 years ago) was working a French station from my QTH in Connecticut, via a 10m FM repeater in Argentina.

Repeaters aside, the 10m FM simplex calling frequency is 29.600 MHz.

I'll monitor those frequencies from time to time and report here if any activity is sighted.
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6 comments:

  1. We had a 10M FM repeater on 29.640 here in Ann Arbor, MI for many years, cross-linked to a local 70cm repeater. When the U of M building it was housed in was re-built, both repeaters were pulled and put in storage. I'm not sure either of them ever made it back on the air.

    It was fun working folks in the Caribbean using my 70cm HT, during 10M openings.

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    1. I have vague memories of a similar system but can't remember where I lived at the time.

      Since making this posting, I've been trying to find out what is involved, and what equipment is available, for setting up a repeater on 10m. A 100kHz split at 29 MHz seems like too little to be able to allow separation between tx and rx but it's proportionally the same (almost) as 600kHz on 2 meters. Unfortunately, not a lot of info out there.

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  2. Something I have thought about is making a low band repeater (10M or 6M) and instead of using a duplexor use a pair of magnetic loops (or maybe a pair of ddrr loops) stacked one above the other (one loop for transmit and one loop for receive). Magnetic loops (and ddrr loops to a lesser extent) have a very narrow bandwidth so they might be sufficient filtering if used by themselves. Magnetic loops have a null so they aren't perfectly omnidirectional but if it was just a repeater at home for playing with it probably wouldn't matter. For radios I myself would use low band commercial kenwood radios but if you know somebody with motorola experience they would work too. In addition to the various commercial repeater controllers you could also use a raspberry pi (or two) running allstar ( https://allstarlink.org/about.html ) to control your repeater. The reason I mention using two raspberry pi's is from what I have picked up reading about 10M repeaters is that the people who put them up tend too stick the transmitter in one high up spot, put the receiver in another high spot several miles away, and link the two (using a pile of horizontal separation to do the job of a duplexor).

    "http://www.wa7x.com/ki7dx_rpt.html" is a page talking about a 6M repeater down in utah including how they made their duplexor which I think you will find helpful.

    Also if you link your repeater (whether a vhf/uhf port or something like echolink) and you feel like doing a little playing you might try using fleetsync or mdc-1200 (https://en.wikipedia.org/wiki/MDC-1200) in addition to a PL tone for access control.

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    1. Thanks for the comment, Isaac. That's an interesting idea about magnetic loops and DDRR antennas and would make for a good experiment. I wonder how much isolation could be achieved and how much is necessary for a repeater with a 50W transmitter.

      I found this page and was initially excited until I read at the very bottom of the page that it was last updated 10 years ago. I emailed Scott anyway, though not expecting to hear that he's still making these conversions:

      http://www.repeater-builder.com/products/micorlbconversion.html

      I have received 5 emails from people describing their experiences using 10m repeaters. It really is a fascinating thing to work one continent via another and my experience was hardly unique.

      Thanks again & 73,
      John AE5X

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  3. 25 years ago... yep, I had a CB converted to 10FM. I remember hearing a repeater in Seattle Washington and, much to my surprise, worked a fellow through that repeater... from the Six Flags Over Texas parking lot. Only got the one chance since the kids (primary reason for being there) were ready to go play. 3 watts and a mag mount. Quite amazing! Mike de N5BGZ

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    1. I remember when converted CB's were a hot item. I had a couple myself back then but only for SSB. I guess they're all gathering dust now but Once Upon a Time they sure provided a lot of fun.
      73 - John

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