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Thread: Sequencer ?

  1. #1

    Default Sequencer ?

    Anyone out there running a combination of Radio to Transverter to Amplifier as a station setup. Currently I'm doing that without any kind of sequencing or delaying between units. The transverters and amps both have RF sensed auto switching. I haven't experienced any problems but am thinking the proper way to run things would be to have the transverter delay a few millisecs prior to the amp turning on so the amp never sees any RF input until it's actually keyed up. If so I think will have to incorporate hard wired keying by the sequencer to each device ??

    By letting each unit use it's own RF sensed transmitting, do I really need a sequencer ??

    A second (sorta related) question - I recently purchased a new amp that has some instructions in the manual that I'm not familiar with. When in SSB/CW mode and the amp has finished transmitting there is a built in delay for a half second or so until it returns to receive mode. However when in FM/AM mode there is no delay at the end of the transmission. Why does it hold the amp on for a several milliseconds when the exciter is key up or I let go of the PTT? This is a Tokyo Hy Power HF-6m amp. Amp works fine. Don't think my sequencer query is in play for that amp but wonder why it has the "output" un-keyed delay?

    - Rich - WA1TRY

  2. #2

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    Ive never used a transverter but I have a thought... To the second question, I believe the delay is present because they anticipated the brief moments in cw and ssb where there is no RF being generated mid transmission. For example, while pausing between letters or words in CW or a pause in speech in SSB.

    It might be possible the amplifiers input has a detector circuit followed by a pin diode acting as an RF switch to stop the RF from continuing on giving the relay time to switch before it lets the RF through to the amplification stage. Not sure though.

    EDIT: page 23 of
    http://www.radiomanual.info/schemi/A....5KFX_user.pdf
    shows an input detector and 2 high speed switching relays, one before the amplification stage and one after. You should be fine if your amp is like the Tokyo hy-power in that manual link
    Last edited by brandon lind; Sun 23rd Dec 2018 at 04:48.

  3. #3

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    Thanks Brandon. The amp I'm using is a low powered one, made for some QRP HF rigs like the FT-817. Input is 5 or 10 watts (selective) with 100 watts out. You are correct, the 1/2 second delay at the end of transmissions in SSB / CW is indeed to hold the amp in transmit between pauses in CW spacing or voice. I kinda figured that.

    90 percent of my HF work in the past was QRP. Just now getting active on HF after a several year hiatus. Wow .. what happened to the bands in the last six years? Guess my new amp purchase was a good idea as I have become active again at the lowest point in this solar cycle.

    As for the sequencer, so far the internal RF input sensing of both the transverter and amp seems to be working okay without any need for any manual keying delays.

  4. #4

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    Don't be too quick to let the low solar cycle get you down! I spend a lot of time on 11m and there has been some amazing conditions come and go. According to a friend who pays close attention to solar activity, this low cycle may be very short. There have apparently been several solar flares with reversed polarity suggesting that cycle 25 might be coming sooner than predicted. Another thing worth noting is that, at least for the northern hemisphere, we are right in the middle of the secondary Sporadic E season. Keep your hopes up, i think its going to be an interesting year!

  5. #5

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    I am addressing the first part of your question. the RF has to be present to be sensed by to ckts and this means it is present at the relay contacts in each device. Over time this will cause pitting and sticky contacts along with carbon deposits on the contacts. My take is to use a hardwire signal delay at each relay to save the contacts from premature demise. You got it right about the sequencer.

    David Reed ac0yw

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