The AM Forum

I am writing some code for a simple sequencer board for my 813 rig.

Simple board that takes an input (ptt) and sequences 4 small relays.

I have it all working (~500 bytes so far!)

My question is, how long between relay closings/openings?  Right now I just sequence 1-4 and 4-1.  Right now I have 50ms between each step.

PTT on:
relay
1 antenna relay switched to TX
2 modulator biased on
3 final biased on and exciter keyed
4 unused

PTT off
the reverse of above

Thanks

Rich

How many ms does it take from the time the sequencer sends the signal for relay 1 to close, does it actually take to close the relay.... allowing time to "settle".?


When you said "simple" sequencer.... it made me wonder how "simple" it is, if it takes a microcontroller to operate it?   ;D

I use comparators, and R/C timing for my E-rigs...

You are right, "simple" is a relative term.  I am immersed in micros all day every day....

I have no idea how long that takes...  The time for the micro to apply voltage is negligible compared to how long it takes for the relay to actually close..  I suppose I could measure it.  Or we could assume it is some fixed small value that will be added to whatever delay I add, we could call it a "safety buffer" period.  A feature!



Rich

I use a Dow-Key relay...................................
 ::)  ::)  ;D  ;D   

In any case, I will go with 50 ms spacing and see how it goes.

73

Rich

shouldn't steps 2 and 3 be interchanged ?

I use a two-step sequencer, all done with relays.  A time delay capacitor is switched back and forth between the coil of the 1st pilot relay and the 2nd one, using a 3rd relay in a latching circuit.  I never timed mine exactly, but I think the delay is about 200 milliseconds, long enough for the capacitors in the TX power supply to bleed down before the antenna relay is switched.  I was having a problem with hot-switching the antenna relay.  I turned a Dow-key into a solid block of charcoal.

In mine, PTT on:

1 Antenna relay switched to TX, receiver switched to s/by, VFO switched on

2 Transmitter, audio equipment, scope and everything else switched to TX condition.

PTT off: Sequence is reversed.

If I had a 3rd step in the sequence, I would switch the transmitter on 2nd and the modulator on 3rd and  vice versa. You don't want to switch the modulator on before the transmitter is on; this could cause you to lose a modulation transformer by running it without a load, particularly right at T/R changeover when transient spikes may occur.

 Pretty much same here. Key the mic PTT pulls in an RC equipped relay that pulls the Dow- Key. The Dow-Key contacts in turn key the TX , through series connected contacts with the mic PTT relay. Unkeying the mic PTT drops out the TX and holds over the antenna to bleed off the stored energy . Actually far simpler than it sounds. Works well for 20 years plus.
 Actual TX sequencing varies from one to another as required .

  Keying any TX energizes a relay bank that takes care of muting all receivers, turning on the "On The Air" light and the scope bias duties.

 The lower power transmitters here do not use the hold over.

Thank you Don and the rest.  All your advice may save me yet.

Rich

This is something I've been trying to get my head around for my bigger transmitters, having lost a couple of modulation transformers now. Even with relays and circuits in place from the factory, maybe the possibility of changing or adding caps to increase the time constants for the HV/modulator and antenna change over.

The relay sequencer, installed in the mod deck, in action.  ACTION!

http://home.comcast.net/~rsoennichsen/IMG_2694.MOV

Rich

Now that's a professional job !