TX on multiple transceivers with one mic continuously?

Discussion in 'Ham Radio Discussions' started by KE7RUX, Apr 8, 2018.

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  1. KE7RUX

    KE7RUX Ham Member QRZ Page

    Theoretically speaking and out of pure curiosity, has any one rigged up one microphone to multiple transceivers in such as way as to make them all transmit at the same time?
    I understand that is illegal in contesting, etc. However, I'll restate that this forum is purely of theoretical interest. 73
  2. K1VSK

    K1VSK Ham Member QRZ Page

    I'll bet you didn't even consider the corollary of using a keyer to key multiple rigs on cw...
  3. K9YLI

    K9YLI Ham Member QRZ Page

    totally simple problem. parallel the PTT circuit. Parallel the mic inputs, adjusting the impedance as needed.
  4. K4VLF

    K4VLF XML Subscriber QRZ Page

    What I always wanted to try, is rotate my transmitter to a vertical position, and see if my NVIS pattern and reach was any better.
    KE7RUX and KP4SX like this.
  5. SM0AOM

    SM0AOM Ham Member QRZ Page

    I have yet to see this in amateur radio, but it would not be illegal in most deregulated countries.

    This is however a very common practice in commercial radio, especially coastal and air/ground. It is known as "group" or "area transmissions" and can in some systems permit group sizes that are up to several tens of transceivers.

    Engineering-wise, it is taken care of by using "conference facilities" where a single microphone or headset modulates all transmitters in parallel.

    If the switch used is analogue, the conference facilities are usually compriced of line amplifiers with high input impedances, driven from mic amplifiers having a low output impedance.

    Digital switches use a time-slot which is dedicated to group transmissions, and is copied to the required number of time-slots in the outgoing direction.

    The GAREX 220 digital switch that I worked a lot with in the 90:s permitted a group transmission size from one operating position of 64.

  6. KA5ROW

    KA5ROW Ham Member QRZ Page

    During band openings I transmitted on 6M and 2M at the same time, but had 2 separate coax lines. I only done that like two times 20 years ago.
  7. AD5MB

    AD5MB Ham Member QRZ Page

    I would use a distribution amp; one input, many outputs, individual controls for output levels, for impedance matching.
  8. K8ERV

    K8ERV Ham Member QRZ Page

    Gee, you could annoy twice as many people at the same time!

    TOM K8ERV Montrose Colo
    KE7RUX likes this.
  9. KS2G

    KS2G Subscriber QRZ Page

    There is nothing in Part 97 to preclude simultaneous transmissions at the same time -- on different bands, on the same band, or even on the same band and mode.

    In most contests, the rules preclude having two signals on-the-air a the same time on the same band and mode, but don't prohibit simultaneous transmissions on different bands or modes.
  10. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I think that's true only for multioperator stations.

    Single op = "one radio" at a time
    SO2R = single op, "two radios"

    However, I haven't actually checked the details. I'm sure someone will, but it seems to me transmitting on more than one band at a time implies "more than one radio."

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