Talked to Mr. Clinton of TenTec service and discussed this with him.
1) The really noisy keying
2) Other ways to hook up the combo.
Here's what we discussed:
1) How to get a single way to handle CW/SSB/FSK and semi-breakin
without the need to switch anything between modes.
2) Timing/hot switching concerns.
3) Noise
It turns out that the TS450/TS850 and perhaps others have an
available T/R signal called TXB which activated immediately on key
closure. This is at the accessory socket. Specifically designed in
delays in the keying circuitry key the RF output stage 10ms later.
This signal stops about 4ms after the keying of the RF output. It
appears that this was specifically designed by Kenwood to prevent hot
switching.
***************************************************
Here's what TenTec says about this method:
Mr. Clinton said that 10ms is plenty of time to prevent
hot switching concerns since the Titan is speced at 2.5ms.
**********************************************************
The remaining of the posting are my words.
The TXB signal appears in all modes (full breakin, semi-breakin, SSB
and FSK)
Unfortunately it's the wrong polarity (+12 on xmit and 0 on receive).
This is easy to invert to obtain the correct polarity. I had a 2003 IC
around which has 7 inverters in a package each handling 50V at 0.5
amp. One could of course use a transistor.
Now here's how it goes:
1) Connect the keyer to the TS850.
2) Connect the +12 T/R signal from the accessory socket to the
inverter. 3) Connect the inverter into the PTT input and put Titan in
PTT mode.
Now for the noise. I found the keyed relay objectionably noisy in
"full QSK" mode. It would not be useable in any 36 hour contest stint
IMHO.
It is audible in the next room (the bedroom). Mr. Clinton indicated
that the vacuum relay is the primary source and nothing can be done
about it. "QSK is noisy"
My solution was to go back to semi-break in mode and set the delay
such that it falls only drops out between characters or "words". This
is rapid enough for me. It eliminates between 60-80% of the
clacking. It is not QSK. I might go back to QSK if chasing a rare
one in a pile-up situation.
IMHO relay driven QSK stinks. However, a PIN switched amp is out of
the question due to cost.
**************
NOTE: The 2.5 ms spec in the manual is apparently only valid for the
Titans using the "hot-shoted" K41 vacuum relays. Mods described here
substitute RJ1A or HC1 relays which have a switching time of 8 and 6
ms respectively. Rumor has it that there are some factory built
Titans with previous relays. They may be cutting it close.
**************************
I can't say that this setup will work for any other type of exciter or
even all TS850's. Use it at your own risk.
de Brian/K3KO
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