Hi Don,
This is a late response.
Kenwood radios including TS-590, 990 and some quite older radios such
as 950 do have a solid state TRX switch. That is pin 7 @ the REMOTE
connector. The signal is called RL (for whatever reason). Mechanical
relay is interfaced at pin 2,3,4 of the same connector.
But this solid state switch has some limitations. Except TS-990, the
logic is active high only and the the transistor can only sink 10mA
(12V). So normally you cannot key the amp directly. You would need
either an open collector switch transistor or an opto-coupler that can
afford more current (and voltage) to sink AND to revert the logic to
active low.
With those circuit you can drive an amp silently, eg. with TS-590 via
MENU setting. However one problem is that you cannot key tube amps
with TX Delay (eg. 25msec) since it doesn't have such setting. (IMO
this is a design flaw, but can be fixed with firmware change.)
The 990 incorporate a new active low logic using FET but it can also
only sink 10mA. So the situation is not much different. If you dare
you can directly key the amp with this.
IC-7600 whose MOSFET switch sinks 200mA (250A) is much more versatile
in this regard.
73 rin JG1VGX
On Tue, Jun 17, 2014 at 3:58 AM, Don Kirk <wd8dsb@gmail.com> wrote:
> The one thing that's keeping me from buying a TS590 for use on the topband
> is the use of a mechanical relay versus solid state switching between TX &
> RX. Had problems develop over a long period of time with my first HF
> transceiver (also a Kenwood) regarding the first character sent being
> shortened in length due to the relay and having a hard time buying another
> radio that still uses a relay for TX/RX switching.
>
> Would love to see the next generation of TS590 produced that uses solid
> state switching but might break down before then and buy a TS590. Wonder
> what others think about the relay in the TS590 and any problems encountered
> (especially when trying to run QSK).
>
> Don
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73 de rin JG1VGX
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