PRC-68 Series Repeater/Retransmission Cable

©Brooke Clarke, N6GCE



Construction

The retransmission cable is wired as shown below:
               (ground) A ---blk----- A (ground) (optional external power goround)
               (ext Ear) B ---blu----> D (mic)
               (PTT)     C <---grn----F (FILL)
               (mic)      D <----org----B (ear)
               (Ext Pwr) E  ---red--- E (Ext Pwr) (optional external power + 12 to 17 VDC)
               (FILL)  F ----wht----> C (PTT)
          This is a symmetrical cable so that whichever radio first hears a signal turns on the other radio (PTT) which acts as the transmitter.
          More investigation needs to be done regarding the setting of the VOL control on both radios.
          The PRC-68 can be used as a transmitter in a repeater setup and probably any radio with PTT.
          More testing needs to be done to see the effects of desense depending on separation and frequency difference.
          This needs to wait until I make up a longer cable.
          27 Jan 2001 - Retransmission/Repeater Cable - Used a 1N4744 15 Volt Zener (RS276-564) with the cathode band to red (pos supply) and in
          series with a 1N4001 (RS276-1101A) with it's cathode end to black (ground).  The 1N4001 is there to raise the clamp voltage by about 0.6
          volts.  This is to prevent the external supply from exceeding a little over 15 Volts.  If it does the zener will conduct drawing a lot of current
          protecting the PRC-126.

External Power Option

          In the above cable (Ext Pwr) E is wired to (Ext Pwr) E and that lead brought out for external power of both radios.
          For the cloning cable there is not much point, unless many radios were being done in a shop environment where batteries were not desirable.
          For the Retransmission cable it would make some sense to use the E to E wire for external power so that the repeater/retransmission system
          could run for a long time.

          U-183 Connector with Strain Relief - the start of a set of cables

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