ad: elecraft

IC-9700-Pre Amp-PA- Sequencer?

Discussion in 'General Technical Questions and Answers' started by N8SAN, Oct 15, 2020.

ad: L-HROutlet
ad: l-rl
ad: abrind-2
ad: Left-2
ad: Subscribe
ad: Left-3
ad: L-MFJ
  1. N8SAN

    N8SAN Ham Member QRZ Page

    Hello Everyone.

    This is multi stage question.
    I have a 9700. SSB electronics SP-200 Pre amp and TE systems 1452G VHF 350watt amp.

    The 9700 can inject 12v over the coax to power the Pre amp.
    The 9700 can also delay the TX so the pre amp is turned off so it can then accept the full power of the amp without hurting it.

    My question is, I'm assuming I cannot run the TE amp in-between the radio and the pre amp as the 12v power source will most likely hurt the radio or the TE amp?

    So does this mean I have to run a sequencer?

    Would this one be acceptable?

    It's 140 dollars cheaper than the SSB one. But will it work correctly?

    Do I also then need a bias T?

    (Actually-it seems the SSB Sequencer includes the Bias T for power insertion to the Pre amp)

    Thanks everyone!

    Last edited: Oct 15, 2020
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The TE amplifier is DC blocked when engaged (operational) and will not pass DC through it.

    Never used the USKI-5 sequencer but looking over the specifications it seems it should do this job fine; remember to buy the relays separately and it does require connection to a computer having an internet connection for programming.

    If you want to save money, W6PQL offers a "4-event" sequencer for $37.50 as a board-level product without an enclosure;
    w6pql sequencer.PNG

    This uses transistor switching, not relays, so will work only with +DC keyed devices; however that should be fine with what you have. Available at
  3. N8SAN

    N8SAN Ham Member QRZ Page

    Got it.
    That's a neat kit.

    I feel very stupid here.
    So the one I linked to and the one you sent all need relays.
    So the relays are only there for keying or powering the associated amp?

    Why then does the one from SSB Electronics have coax connectors?

    If I were to use the USKI-V or the one you linked, how does the wiring actually work?

    I would run coax from the 9700 to the TE then to the Pre Amp.
    So from some accessory port on the 9700 would trigger the sequencer to start upon TX keying.

    It would cut power to the pre amp....then trigger the TE Systems.

    Is that correct?

    And because the remote trigger in the TE amp is connected it will not transmit power by (RF sensing) and it'll wait for the remote trigger by the sequencer?

    I know this is probably very elementary, but I think that's how it works.

  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    No. The one you linked to needs you to buy the relays. The one I showed doesn't use any relays, it's solid-state switching.
    Yes, but only for the one you pointed to. The one I pointed to doesn't use any relays and keys stuff without them.
    You didn't provide a link to that one, so I don't know what it is.
    They are for "hard keying" accessories, in proper sequence. If you use a sequencer, you use the IC-9700 to key it, and then it in turn would first bypass the masthead preamp (one control cable) and then key the TE amplifier (another control cable). When you release the mike (or whatever) from the IC-9700, it will then "unkey" first the amplifier, and then the preamp to put the amp off line and the preamp in line, all within a matter of milliseconds.
    Not quite. It wouldn't cut "the power" to the preamp, it would switch the relay in the preamp so it's bypassed when transmitting and in line when receiving.
    You can't use "RF sensing" on the TE amp for this, at all. That would defeat the whole purpose of the sequencer. You have to use a keying control line.

    I admit I've been doing this for so many years now (since about 1974 when I first got into moonbounce work) it seems natural and I don't really think about it. But I can see how a newcomer might get confused.

    My first "sequencer" was a little kit sold by N6CA, a very long time ago (I never designed one, myself) and it worked so well I still use it after 40+ years. Chip doesn't sell these anymore, but the instructions might still be on line someplace (didn't look).
  5. N8SAN

    N8SAN Ham Member QRZ Page


    This one here... for 280$

    So just a couple wires to each piece of equipment? Seems overly simplistic when companies get multiple hundreds for these things.

    There's 3 connectors on the SP-200. 2 coax and one for 13.6V. I was referring to that 13.6v as "the power" to the pre amp. Maybe that's not correct terminology.
    :oops: But I see what you mean. The voltage is simply to move a relay.

    Right I get it...."... will not transmit power by (RF sensing) and it'll wait for the remote trigger by the sequencer?"
    I meant that in a normal hookup, when the radio is keyed, it normally works by RF sensing, but since the control cable is connected to the control port on the back of the TE amp, it will NOT use RF sensing. That's all.

    Thank you. :oops:

    That's awesome!

    Thanks Steve, I appreciate your patience and descriptions.
    Hard to argue with the 37 dollar long as it's not a huge lead time.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    The $37 kit from Jim W6PQL looks like a very good deal to me. Remember, it's just a circuit board and really should be mounted in an enclosure with connectors (a bit of extra cost and work).
  7. N8SAN

    N8SAN Ham Member QRZ Page

    I agree! It's definitely the front runner!
    A box and connectors with some work, won't add much cost.

    I am trying to grasp the connections.
    I know the Pre-amp needs 13.5 and 290mA to operate.
    I have yet to determine what the TE systems needs. Or how to properly wire to the RG45.


    If I'm reading the schematic correctly, when each event is activated it's outputting 12 on their associated pad.
    Event 1 pad- triggered- 12v.
    100ms later...
    Event 2 pad- triggered -12v
    100ms later...
    and so on.

    When release the PTT, it's just reversed.

    If that is the case would I then need a NC relay that will open when triggered to remove power from the Pre amp? Otherwise, it would be ON during transmit and off during receive? If the pads indeed supply 12v when on.

    I feel dumb somedays..... .

  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'm unfamiliar with your preamp.

    If it's designed for masthead use (weatherproof and all that) it should have two separate DC (not RF, not coaxial) lines running to it: +12Vdc (or 14V, or whatever) and ground return for that, and a "control signal" line to key its internal bypass relay. Minimum of three wires, there, maybe four.

    You leave the DC power line connected all the time and "key" the relay line.

    The TE Systems amps use +12V (or +13.8V or whatever you have) relay keying at about 100mA. The amplifier provides the +12V, not the sequencer. You close a contact to ground on transmit to activate the amplifier relays inside. The sequencer provides that contact closure to ground, although the W6PQL unit does this electronically using transistors and not relays. Should work fine, current is low and the keying line does not have to go all the way to "ground" to work.

    Call Jim on the telephone if you can, and ask him. He makes his own amplifiers but is likely familiar with the TE Systems keying requirements.
  9. N8SAN

    N8SAN Ham Member QRZ Page

    This is what it has....

    3-coax. Center simply being power. It CAN also be powered via feedline as discussed earlier.
    I guess I'll have to contact SSB about this.....

    OH. I got it! That makes sense.

    Yeah! I see his amps too! Stout equipment!
    I'll reach out to him.

  10. AJ4SN

    AJ4SN Ham Member QRZ Page

    I've purchased from W6PQL, and he is very good to work with.


Share This Page