The AM Forum

 Hello all :
  I'm changing the radio room layout and was thinking of changing the stations controller sequener. so I'm asking everyone what do u use for contrlling the stations ant,trans,rec,?? ;D ???
 73 John

I heard that W1VD has a sequencer but I don't see it on his web page?

Hey John

  These work fine, It's a handbook design.

http://www.downeastmicrowave.com/PDF/trs.PDF

Used them for years on VHF.

/Dan

Manual ant selector switch (dipole/beam/etc.) switch.

Dow-key relay with external contacts...

                    _-_-bear

I am also struggling with this issue and assume we want to sequence vintage gear.  This is one of the stumbling blocks in the way of my getting my transmitters on the air.  I have to homebrew a sequencer but first I have to learn how to build a chassis and cabinet.

The problem to me has to do with sequencing the T/R relay among other things which is part of what I think he wants to know about.  I know a lot of hams use the dow-key things or something similar but I see a problem with using them in the traditional method:

Most vintage rigs are switched into transmit by energizing the primary windings of the medium v. and h.v. power supply transformers. 

The T/R relay coil is also energized by the same switch (via 115 v. on a socket on the rear panel usually).  It seems to me there is a chance of the relay hot switching with this method.  If the relay settles in before carrier comes on the feedline to it, then I would think it would open on break before the carrier drops.  You can't tell for sure with the D-K jobs because they are enclosed and you can't see the contacts switching. 

I have looked at sequencing circuits; some don't seem very well designed; others are way too complex employing microprocessors etc.  Don K4KYV has come up with one that looks like a good idea and is simple, for timing the energizing and de-energizing of the relay coils on make and break.  He published it in ER but off hand I don't remember which issue. 

Rob

http://www.w2drz.ramcoinc.com/Sequencers.htm
Been using these for years in E rigs projects.

work great

Brent

I just use a Dow-Key relay.  The same one I bought as a novice 50 yrs ago.  The HV supply is delayed after the antenna relay.  If the Dow-Keys fails to trip the HV supply won't come on.

On receive everything drops at the same time.  There may be a split second of time where the antenna is not connected to the xmtr with a little HV still on the finals.  Doesn't seem to bother the 813.

Fred

I can't not imagine not having a central station sequencer  :D

Mine is 30 years old, homebrew.  There are 2 steps:

A) Receive to Transmit -> Everything hooked to "step 1" keys (receiver mutes, ants switch from Rcv to xmt, etc) 200ms later, everything hooked to "step 2" keys (rigs go into transmit, etc.)

B) Transmit to Receive -> Everything hooked to "step 2", above unkeys (rigs are put into standby, HV supplies unkey, etc) 400ms later, everything hooked to "step 1", above unkeys (receivers are unmuted, ant switches to receivers, etc)

Any other sequencing which may be required is part of individual transmitters, since this varies quite a bit with each unit.

The circuit consists of discrete transistors, R/C time constants, a power supply and some relays.  The sequencer has 4 outputs: 120VAC and 24VDC for "step 1" circuits, and the same for "step 2" circuits.  I run 4 conductor wire all over the shack, with 1 pair hooked to "step 1" and the other pair hooked to "step 2" (all 120V these days, but I used to use 24VDC way back when for lots of relays in the shack).

It is one of the most reliable pieces of equipment in the station - I have never done anything to it in over 30 years other than build it!

You could probably whip it up in a couple of hours from junk box parts, assuming you had an old rack mount chassis lying around and didn't have to do any metalwork.  Mine is built into something that came off the scrap pile when I was in college (wow, that makes it close to 40 years old!!! - good thing I'm not getting older  ;)  )

Regards,

Steve

My circuit is two-step, like Steve's, but uses no active components. The delay is achieved by using an R-C circuit between relay coils and the relay voltage source. The delay capacitor is transferred between the step 1 relay and step 2 relay, using a third relay in a latching configuration. The third relay latches as soon as the circuit is switched to the transmit mode, shifting the timing capacitor to the opposite control relay and holding it there until the T/R function has fully toggled back to receive mode. I forget which issue of ER it was in, but I'll e-mail anyone the circuit diagram upon request.

I had one problem with mine after about 4 years of flawless operation.  It became flaky and spastic.  Turned out that one set of relay contacts was making a poor and intermittent connection.  I have plenty of spare relays, so I just replaced the bad one, and the circuit has worked perfectly ever since. I use little DPDT 12v relays that come enclosed in about a 3/4" X 3/4" X 3/4" plastic cube.  The power source is 24v, with a dropping resistor in series with each relay coil. The dropping resistor, in conjunction with the timing capacitor, produces the delay.

Actually, the  step 1 and step 2 control relays in the sequencer unit serve as pilot relays to activate a set of additional heavier duty control relays, since some of the main relays in the equipment pull a substantial amount of initial surge current at 24 volts and 120 volts DC, plus the antenna relay has a heavy duty coil that runs off 120v a.c., and the tiny contacts in those little dc relays in the sequencer unit would likely fuse together or disintegrate in no time flat.

 My PTT line keys the T/R relay directly. The T/R relay contacts VIA an intermediate relay then keys the transmitter. Upon dropping the PTT at the mic , the intermediate relay unkeys the TX promptly and a  time delay holds the ANT at the TX output for .2 sec .

  No hot switching of the Antenna /TX contacts. The TX will not key until changeover is made.