Hello Ken
Yes , you are right exactly.
I had 1989 - 1994 modified system , where I did listen even K4 / big Vacuum
relay was
activated,
Now I was thinking same on Orion and did not remember first my modification.
I will do same modification soon into new setup.
Sorry my error and thank you for good remaining text , which is good to save
anyway.
GL es 73 ; Marl OH3LX.
-----Alkuperainen viesti-----
Lahettaja: tentec-bounces@contesting.com
[mailto:tentec-bounces@contesting.com]Puolesta Ken Brown
Lahetetty: 10. marraskuuta 2003 3:09
Vastaanottaja: elstar@elstar.fi; tentec@contesting.com
Aihe: Re: VS: [TenTec] Titan 425 & TT Transceiver QSK
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
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