[AMPS] RE: TS-2000

[Peter Chadwick]

Tom says:

>Keying speed is relatively unimportant as to bandwidth

Well, yes...............and no. At high/very high speeds, the rise and fall
times can be a greater percentage of the dot. But the main point there is the
claim that at high speeds,  hard edges are easier to read. As I can just about
do contest exchanges at 30 wpm or so, and certainly can't have a chat at that
speed, I couldn't judge. I usually figure that 10-90% rise and fall time of
around 2ms is OK.

One of the worst radios for key clicks is the FT102, even with Yaesu's mods.
That had a sinx/x spectrum going out about 8kHz either side at a 30Hz keying
rate. It wasn't that difficult to get the occupied bandwidth (i.e.99% of power)
down to about 100Hz, though.

>I've measured solid state zero-bias transistor amps at about the 
>same IMD level as the TS-2000.

Infinite perfect limiting produces 3rd order IMD products 13dB down on each
tone.

> I wonder what they did wrong? 

I wonder how they managed to design it like that! Surely it didn't happen by
accident?

73

Peter G3RZP





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