Dual Watch Using Two TS930S Transceivers

[N1UK]

I am planning on using two of my TS930S rigs to provide a dual watch function i.e. receiving two frequencies simulataneously with one rx in the left ear and the other rx in the right ear of my headphones. 
 
I am planning on using an rx signal spiltter like this so that I can run both radios from my beam
 
http://www.universal-radio.com/catalog/preamps/1420.html
 
 
I am also planning on using 3 coaxial relays to bypass the rx splitter when on tx and also to provide a dummy load for the receiving radio when on tx.
 
I think that if I put a DIN plug in the transverter socket at the rear of the rx rig then this will disable the power amplifier in the rx rig.
 
 
Can I join the PTT lines of both the radios together and pull them down with the same foot switch. Will I need any blocking diodes (diode or'ing) or is it safe to join the two ptt lines together and pull them down as one line?
 
 
thanks Mark N1UK

[W9GB]

Can I join the PTT lines of both the radios together and pull them down with the same foot switch. Will I need any blocking diodes (diode or'ing) or is it safe to join the two ptt lines together and pull them down as one line?

Not a good idea to tie the PTT lines of 2 different radios together.

Get a DPDT or DPST footswitch, so each radio has its own Pole on the switch.

[W8JX]

Not a good idea to tie the PTT lines of 2 different radios together.

Get a DPDT or DPST footswitch, so each radio has its own Pole on the switch.

Better yet two foot switches, one for each rig which also controls relay sequence. More fail safe.

[HB9PJT]

Yes you can use one footswitch for two rigs without problems. Just use for every rig a diode. Anode separate to every rig and both cathodes to the footswitch.

73, Peter - HB9PJT

[TANAKASAN]

For SSB use this system will probably be OK but you need to think really carefully before using the system on CW, especially if using full break-in. The problem is the switching time of the various relays and how they interact, your two main dangers are:

a) Hot switching, the first CW character is generated before all the relays in the antenna path have closed.

b) Blowing a receiver front end as the first CW character is generated before the receiver dummy load is switched in.

Like good comedy timing is everything here but there is a solution. In 2007 VE2ZAZ published an article in QST titled 'The "At Last!" Radio TR Sequencer' and this might solve your problem. A better solution would be to modify the two rigs so that neither of them can go into transmit until all relays have switched.

Tanakasan

[W9GB]

Sequencers are used in EME, satellite, and microwave configurations.

IF you desire to go Exotic, you could use Jim, W6PQL Relay Sequencer.
http://www.w6pql.com/relay_sequencer.htm

Jim's solutions are to protect and sequence LNA used in EME and microwave work.
http://www.w6pql.com/lna_sequencing_and_protection.htm

High Current DC switch
http://www.w6pql.com/high_current_solid-state_dc_switch.htm

Kits and PC boards that Jim, W6PQL offers to radio amateur community.
http://www.w6pql.com/parts_i_can_provide.htm

[N2CJ]

The two receivers must be phase locked for true diversity. See here: http://www.w8ji.com/polarization_and_diversity.htm

[AA4PB]

I don't think he's talking about diversity. He just wants to listen to two separate signals at the same time, one in each ear.

If you tie the PTT lines together, even with diodes, then pressing the PTT will key both radios at the same time. Hows that going to work with the two radios connected to a single antenna?

I think you are asking for trouble (equipment damage) by trying to do all the relay switching for transmit with a single antenna. First off, that combiner is probably not rated to handle transmit power so the active transmitter will have to bypass it and go directly to the antenna. At the very least, I'd use a dual foot switch controlling two Dow-Key RF relays with control contacts. I'd wire the PTT from each radio to its RF relay. That way when you press the radio-1 foot switch it's relay closes which in turn keys the PTT on radio-1. That ensures that the antenna is connected before the PTT is closed and you won't be transmitting into a high impedance or the other transceiver. The other issue is RF isolation between the open relay contacts. If your transmitter is generating 100W, the capacitance between the open relay contacts may put a good deal of energy into the other receiver. Even if its on a different frequency or a different band you still have the potential for damage to the receiver front end.