Topband: Loud clicks

[Thorvaldur Stefansson]

hello,

although I did not have key clicks I have been concerned with protection of
my receive pre amplifiers from my Beverage antennas and I have just
installed a DX Engineering Time Variable Sequencer Unit on my main
transceiver.

http://www.dxengineering.com/Parts.asp?ID=1232&PLID=214&SecID=116&DeptID=12&PartNo=DXE-TVSU-1

This unit will take care of the sequencing of the entire chain from the key
to the amplifier and I must say, I am experiencing a new dimension of
smoothness on CW along with peace of mind.

It would be great if the general issue of Key Clicks would be dealt with, I
know that both my Yaesu FT1000MPs (early models) had key clicks and had to
be modified.

73
Thor, TF4M

"The language of Amateur Radio is CW"



2010/1/3 Tod -MN <tod at k0to.us>

>
> A number of years ago I fabricated a very simple circuit to "delay" the
> "Key
> Down" signal sent to the transceiver slightly while allowing that signal to
> be sent to the amplifier to change the amplifier relays from receive to
> transmit during that slight delay. The delay was 20 milliseconds which
> allowed the amplifier relays to change and stop bouncing before the
> transceiver began the keying process.
>
> When the "Key Down" signal changed to "Key Up" the transceiver "Key Down"
> line remained "Key Down" for an additional 20 milliseconds so the actual
> length of the RF envelope sent out from the transceiver was exactly the
> same
> as if there was no special circuit in the line to the transceiver.
>
> In addition, the "Key Down" line to the transceiver was sensed and for 30
> milliseconds after the transceiver "Key Down" line changed to "Key Up" the
> amplifier change relays were held in the transmit state before being
> allowed
> to change to the receive state. This 30 millisecond delay allowed the RF
> envelope to drop to zero before the amplifier relays started their change
> over.
>
> In principle this meant that the amplifier relays were switched to transmit
> and when they were in the transmit state the transceiver was keyed and sent
> out an RF envelope. About 10 milliseconds after the RF output had ended the
> amplifier relays were returned to the receive state. The relays were 'cold'
> switched and there was no possibility of "clicks" due to amplifier relays.
> If clicks were generated in the transceiver, however, they continued to be
> amplified as 'clicks'.
>
> When I used this circuit I did not need to adjust the keying on the
> transceiver from its normal setting for use without the amplifier. The
> amplifier I first used this on was a Collins 30S1 which did NOT have QSK as
> a feature.
>
> The circuit used low cost, easily available components to achieve the time
> delays. It was external to the transceiver and the amplifier so there was
> no
> equipment modification. If there is no QSK built into the amplifier it may
> be necessary to add one high speed relay [ preferably a vacuum relay like
> an
> RF1D or similar ]. Since the relay does not have to handle the possibility
> of switching while significant RF current is flowing through the contacts,
> the specifications for the relay will not be as demanding.
>
>
>
> Tod, K0TO
>
>
>
>
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