>
>
>> On a Linear Amplifier would having the output relay of the amplifier
>> operate 20 millisecs before the input relay be sufficient to keep RF
>> from being on the output contacts before they are closed?
>
>2 milliseconds is enough, as long as it is always there and the
>contacts don't bounce that long.Most relays are done bouncing
>within 1 ms.
>
// Hotswitching of the RF input relay contacts is half of the problem.
This can be ameliorated by replacing the transceiver's amplifier control
relay with a switching transistor, and by using an input relay that
closes in less time than it takes for the transceiver to begins
delivering RF on TX. The other half of the problem is the possibility of
hotswitching the output relay. Again, quick does the trick. However,
for CW use, the relays must open quickly as well -- otherwise they will
not be able to close quickly enough for the next dit or dash. This can
be achieved by putting a "break-time control resistor" in series with the
counter-EMF diode across a relay's coil. Typically, this resistor is
approximately 2x the coil resistance. [See RL-1's coil circuitry on
Figure 7 on my Web site.]
- In a nutshell, for RF amplifier relays, mo' fasta is mo' betta.
>Be sure it opens AFTER the input relays opens also!
>
// If the transceiver stops delivering RF when the amplifier relay coils
receive the 0v signal to open for RX, the RF relays can not hotswitch.
To the best of my knowledge, no transceiver does so - provided that its
amplifier control relay has been replaced with a switching transistor.
[see "Circuit Improvements for the TS-440S" at:
http://www.vcnet.com/measures/440.html - its under "Transistor
Installation Notes" - also see Q3 on Figure 7B on my Web site.]
cheers
- R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures.
end
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