Need help connecting 756pro2 to fl2100b

Discussion in 'Amateur Radio Amplifiers' started by KG5DLF, Jun 13, 2019.

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  1. KG5DLF

    KG5DLF Ham Member QRZ Page

    I just got a fl2100b and i need step by step instructions on the hook up for rca plugs (alc and send).
    also do i need the alc?
     
  2. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    I used my FL-2100B with a PROIII. Here is how I did it.

    On ACC2 jack, pin 3 goes to ground when you transmit, and pin 7 has 13V on it. Using an SPST or SPDT relay, wire these pins to the coil. Wire the normally open contacts of the relay to the RLY and E screws on the back of the amp.

    Under normal conditions, the amp has a negative voltage across the RLY and E contacts. You do not want to feed this into the ICOM send jack.

    When you go into transmit, the relay contacts will close and key the amp. The relay isolates the amp from the radio.

    Keep the RF output under 60W and you won't need the ALC line.

    Max
    VE3TMT
     
  3. AA5CT

    AA5CT Ham Member QRZ Page

    Why not just use the "Send Control Jack" on the Pro2 (#10 below)?

    Or, use the "Send Control Jack" to control an external relay? #10 is a lot more rugged than using pin 3 in ACC2.

    IC-756ProII_Rear_Panel.JPG
     
  4. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    The voltage on the keying line of the amp is negative.

    I ended up putting the relay inside the amp. The RLY and E terminals are now GND and 13V. As long as one of them switches off in RX, the amp keys just fine.

    Max
     
  5. AA5CT

    AA5CT Ham Member QRZ Page


    P18 of the Pro2 manual:

    The specifications for the SEND relay are 16 V DC 0.5 A. If this
    level is exceeded, a large external relay must be used.



    Relay contacts are polarity insensitive the last I knew ...

    So, what is the voltage on the fl2100b? Over 16V?
     
  6. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    Do a Google search. Direct connection is NOT recommended.
     
  7. KG5DLF

    KG5DLF Ham Member QRZ Page

    so i should use an external relay?
     
  8. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    I would not think twice about it.
     
  9. AA5CT

    AA5CT Ham Member QRZ Page

    "Send Control Jack", handles 1/2 amp at max 16V.
    It is a relay contact.


    Pin 3 on ACC1 or 2 per the manual:
    Ground level : –0.5 V to 0.8 V
    Output current : Less than 20 mA
    Input current (Tx) : Less than 200 mA
    Connected in parallel with ACC(2) pin 3.
    *NOT* a relay contact.


    Which is more rugged?

    (Note above I did write: use the "Send Control Jack" to control an external relay.)

    Note also that Pin 3 is an INPUT.
    If you ground it the rig transmits.

    From the manual P13:
    Pin 3 - Input/output pin.
    SEND Goes to ground when transmitting.
    When grounded, transmits.
     
    Last edited: Jun 14, 2019
  10. VE3TMT

    VE3TMT XML Subscriber QRZ Page

    I would not feed a negative keying voltage into the radio. I've used the relay method for years.
     

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