[Amps] Sequencing relays

[W7RY]

What are you using to key the amplifier? The relay in the rig or an external switching circuit from the PTT line (or +12 volts keyed)?

As you can see from the WD7S site, Paul DOES NOT use the built in relay of the exciter. Using the relay in the exciter really slows down the relay switching time.

73
Jim W7RY

  ----- Original Message ----- 
  From: Rick Stealey 
  To: amps at contesting.com 
  Sent: Saturday, November 22, 2008 6:37 AM
  Subject: [Amps] Sequencing relays





  I had a couple emails from guys asking about how I measured the switching times 
  in the amp and exciter.
  All relay measurements in amp are made with no filament voltage and no high 

  voltage. No exceptions, naturally.

  I use a 555 timer and a couple 
  2N2222s to generate a square wave to key the 
  rig on cw and give me a place 
  to trigger from.  1 pulse of 160 ms, then 840 ms off.
  Then I leave that alone. That trace becomes my t0 (T 
  zero).

  Then I look at the rf out of the exciter with channel B and note that 
  time 
  (0-30 ms, adjustable on 1000MP). Just clip the probe on the SO239 connector.

  Then I unsolder a lead off the amps 
  output relay and use a little resistor 
  and battery so I can see a voltage 
  change when the contacts operate and 
  measure that time with channel 
  B.
  Same for the input relay and the relay that operates the bias.
  The only 
  parameter that is easily adjusted in my setup is the time after key 
  closure 
  before the RF appears out of the exciter (FT-1000MP).  In order, 
  here are my 
  results:
  T0
  T0+2 ms - PTT (amplifier key ) line out of the exciter to 
  amp
  T0+5 ms - amp input relay and bias relays close
  T0 + 13 ms - output 
  vacuum relay operates
  T0 + 15 ms (adjustable via menu) - RF out of the 
  exciter

  Summary and "where do we go from here" ------
  My amp and 
  relays are happy with not getting RF drive till T0+15.  This may 
  not be good 
  enough to prevent chopping of dots in cw, haven't figured that 
  out 
  yet.
  Efforts could be expended trying to speed up the vacuum.  There are 

  techniques to do this.
  Before I discovered the menu that allowed me to 
  delay the RF by 15 ms it was 
  outputting immediately which would NOT make 
  that vacuum relay happy.
  Someone told me he had an Icom 756Pro II and it did 
  not have a delay.  This 
  is surprising and disappointing, if true.  Because this is the easy, fast fix.

  An 
  alternative to delaying rf out would be to delay the bias relay in the 
  amp, 
  say to 15 ms.  I need an education on that matter.  If RF drive hit the 
  amp 
  at T0+2ms, before the amp rf relays operated, it would initially dump rf 
  into 
  the antenna, then 3 ms later into the cathode (assuming G-G) of the amp, then the 

  vacuum relay would switch cold, but rf would be going into the cathode with the 

  amp in cutoff.  Then the bias relay would switch and apply power out the vac 

  relay. All the relays would be happy, but how would the exciter and the amp feel about having rf go into the cathode with the rig biased off.
  Any comments on this?

  Rick  K2XT


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