[Milsurplus] TBW Key Clicks/ Chirps

[Ray Fantini]

Working on the TBW transmitter in preparation for the CX contest and am
about to do the unthinkable, going to do a modification to inject
negative bias on the grid of the oscillator and first stage amplifier.
have been working with this transmitter for a while now and with using
external keyed power supplies still have issues where the oscillator and
IA generate noise when the key is let up. This transmitter is being used
in the full brake in mode for CW keying. have wasted many of hours
trying different combinations of filter capacitors and bleeder resistors
in the power supplies, different methods of keying the supplies on and
off and the like. myself am beginning to think the original design may
have been flawed, although I have been told that with the 800 cycle
power supply key clicks and chirps were not a problem. So it has come to
this, on the low side of the IA grid current meter where the oscillator
grid is brought to the same point and then runs to the keying relay I
will install a new line to inject bias voltage. this point is keyed to
ground when the key is closed, while the key is up it floats open. the
new line will bias the two tubes into cut off at that point and when the
keying relay closes the point will go to ground just like the
transmitter has always. fortunately this is a modification that requires
no physical changes other then snaking a new wire into the transmitter
and there transmitter operate and sounds 100% better on the air for it.

Thus the gauntlet is thrown down, I am certain that all the experts out
their can get the TBW to work without chirps or clicks from a 60 cycle
AC supply but I cannot do it without this modification.
Ray Fantini KA3EKH