Re: VS: [TenTec] Titan 425 & TT Transceiver QSK

[Ken Brown <ken.d.brown@verizon.net>]

Hi again Mark,

There are only two relays in the Titan 425 amplifier that have RF 
signals running through them. There are other relays in the power supply 
and some relays in the amplifier which switch power and control signals. 
The two relays that have RF signals going through them are K4 (the 
vacuum relay) and K3 (a reed relay) on the input bias board. K3 switches 
the exciter RF drive to the lowpass filter before it goes to the 
cathodes of the 3CX800s. The receive signal does not go through K3. K4 
connects the RF input jack to the RF output jack (bypassing the 
amplifer) when in receive or standby mode, and in the transmit mode it 
connects the RF output jack to the Pi-L network tank circuit output of 
the amplifer. There are no pin diodes, nor is there any other path by 
which signals from the antenna (connected to the RF output jack) can get 
to the RF input jack and then to the transceiver. Only by leakage 
through K4 could a receive signal get to the transceiver when K4 is in 
the energized (transmit) state. If there was sufficient leakage (perhaps 
by capacitive coupling) through K4 for a usable receive signal to pass 
through it when it is energized, there would be other undesirable 
consequences, such as feedback making the amplifier an oscillator.

In order to have full QSK, wherein you can receive signals between the 
dits and dahs of a morse character, K4 must switch from the transmit 
(energized) state to the receive state during the non-transmit period, 
and then back to energized again before the beginning of the next dit or 
dah.

This is based on the schematic I have for the Titan 425 amplifier I own. 
Whether there are other versions of the Titan 425 that do it differently 
I cannot say.

DE N6KB


_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec