Question concerning Part 97.205 repeater station

Discussion in 'Ham Radio Discussions' started by KX4O, Jan 23, 2020.

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  1. KX4O

    KX4O Ham Member QRZ Page

    All,

    Part 97.205 subsection (b) says this...

    A repeater may receive and retransmit only on the 10 m and shorter wavelength frequency bands except the 28.0-29.5 MHz, 50.0-51.0 MHz, 144.0-144.5 MHz, 145.5-146.0 MHz, 222.00-222.15 MHz, 431.0-433.0 Mhz, and 435.0-438.0 Mhz segments.

    One of the byproducts is my two local frequency coordination organizations allow and document a way to have AX.25 packet radio simplex or duplex for 6m, but simplex only for 2m. 6m example from TMARC.org...
    • 50.600 - 50.780 Digital (can be paired with 51.100 - 51.280 and/or 51.600 - 51.780)
    • 51.100 - 51.280* Digital (can be paired with 50.600 - 50.780 and/or 51.600 - 51.780)
    • 51.600 51.780* Digital (can be paired with 50.60 - 50.780 and/or 51.100 - 51.280)
    A duplex packet option is defined above, but not so for 2m packet options...
    • 144.910 - 144.990 Simplex / Packet
    • 145.010 - 145.090 Packet
    • 145.500 - 145.800 Simplex
    Long story short... duplex packet on 6m is cool, but perhaps a no no on 2m.

    Question:
    • This goes way back, but do any of you old timers know how and why the 2m exemptions were made... especially the curious midband 145.5-146 MHz segment?
     
  2. N8HM

    N8HM Premium Subscriber QRZ Page

    145.8 - 146 is the satellite segment, so that's the reason for excluding that (same reason repeaters are not allowed at 435 - 438). I'm not sure why 145.5 - 145.8 are excluded.
     
    N2EY and KX4O like this.
  3. KX4O

    KX4O Ham Member QRZ Page

    Thank you for the tip about the sat segment. The 145.5 - 145.8 is where the lion's share of packet activity (simplex) exists in our Northern Virginia area based on the survey we just finished. It's much more busy than the 145.0 to 145.1 segment which surprised me. More to learn.
     
  4. W1VT

    W1VT Ham Member QRZ Page

    Amazingly, despite being launched in 1974, Oscar 7 still uses that 2M satellite segment.
     
    WE4B and KX4O like this.
  5. K7JEM

    K7JEM Ham Member QRZ Page

    There were a lot of changes made to the 2M band privileges back in the 70's. Early on, techs were only allowed operation from 145-147 MHz, the upper and lower MHz of 2M was off limits. Sometime in the early 70's (IIRC), the 147MHz area was allowed to be used by techs. Techs were finally allowed to use the full band somewhere around 1978. Also in 1978, the lower repeater sub band from 144.5 to 145.5 was added, previous to that, repeaters were only allowed from 146-148MHz. The area from 144.0 to 144.5 was made off limits to repeaters to give space for CW, SSB, and other modes. The area from 145.5 to 146 was set aside because of satellite operations, as well as other operations that did not use repeaters.
     
    KX4O likes this.
  6. KX4O

    KX4O Ham Member QRZ Page

    What I'm ultimately up to here is to experiment with the method outlined in this old, but quite interesting document...


    I guess the experimenters above used an FM voice repeater frequency pair for their test. I'd like to give this a go in our area on something like 145.050/145.650, but think I may be hemmed in... unless you all have some really cool ideas or advice. Seems like 6m would be no problem, but 2m duplex is a hope.
     
  7. K7JEM

    K7JEM Ham Member QRZ Page

    You don't have to use a 600KHz offset for your repeater, but it would have to remain in the repeater subband. 145.65 is not in the repeater allowed area, but anything above 146.0 and below 148.0 would be. You should be able to find 2 frequencies that would work in your area, and not bother others (but maybe not). 2 meters requires some relatively expensive duplexers, compared to the 440 band.
     
    KX4O likes this.
  8. K7KBN

    K7KBN Ham Member QRZ Page

    Even with all that lead-bearing solder, too!
     
  9. K0RGR

    K0RGR Premium Subscriber QRZ Page

    Contact your local repeater coordination council for advice. After they tell you to go straight to Hell for the third time, ask them again, politely. Personally, I think it's a wonderful idea, but finding an unused repeater pair might be a problem. Perhaps your best bet is to find a repeater owner who would be willing to let you experiment with it. You'll need to find a way to efficiently handle the ACKs and NAKs from the receiving station.

    I think there are other ways of sending data that are tremendously more efficient. Investigate NBEMS. We routinely send large practice messages at more than 400 WPM using some of the more exotic modes, and checksums are used to verify reception.
     
    N2EY likes this.
  10. KX4O

    KX4O Ham Member QRZ Page

    I have a good rapport with our local RCC. I do need to open a dialog with the one just to our south since there is lots of spill over into their territory from our particular spot. Typically these folks they don't want to get involved with anything much other than FM repeater coordination with the exception the RCC to our south explicitly suggests several duplex "packet" frequency pairs for 6m indicating an interesting history that led to this.
    I run one and am examining the possibilities.
    We have some of those modes in our little chart here...
    [​IMG]
    I probably should re-investigate the latest and amend. I think I have 3 GHz in there as well, but that's as good as gone. Evolution.
     

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