Topband: Clicks

[Tom Rauch]

> I have noticed that the distinct unique pleasures of a topband pileup
> (vs 20 meters) what with the far more courtious and knowledable
> operatoring is somewhat offset by the severe amount of keyclicks I am
> hearing here even with an unamplified loop. I can readily get by with
> my noise blanker on even in a pileup except when some of those
> keyclickers are on.

Using a noise blanker is a bad idea, but you know with a simple 
design change we COULD use our blankers with overload 
problems....but that is for another day.

After some more thought, I revisited the FT1000(D) I have. If anyone 
wants to send me copies of the IF board, RF board, and AF board 
schematics of the MP  and MP MK V service manual (which also 
click like crazy) , I'll look at them also. 

I now have modified my radio with a new system. It appears 
possible to make simple plug-in adaptors, except for one 
component that needs to be soldered to the pins of an IC chip (an 
easy task, since the two adjacent pins are common and the chip is 
a large DIP quad-gate). If it works in the MP like the D, maybe  
someone can produce a cheap plug-in board. 

Rather than the original waveshape mod, I now added a small DIP 
relay. The DIP relay is wired to force the radio to transmit CW 
through the 250Hz CW filters, rather than the stupid idea of using 
the 2.4kHz SSB filters to "filter" the CW.

Some hang-time needs to be added beyond the filters, so the 
switched mixers and amplifiers after the filters do not truncate the 
falling edge of the shaped filtered waveform and add clicks.

None of this involves removing any boards, and when I get time I'll 
lay out a small board with hedders that will plug in between the 
harness and the IF, AF, and RF boards.

The result of this mod is the transmitting CW is filtered by the 
250Hz filters, with removes virtually all keying sidebands more than 
150Hz up and down from the main signal. 

It amazes me that nearly every radio has all the filters inside to 
limit CW transmit bandwidth to a few hundred Hz, yet the 
manufacturers use 1930's technology R/C single-pole filters....and 
even at that use too fast a rise and fall....to shape CW.

I've concluded most otherwise good engineers simply do not 
understand CW. More than likely the older engineers who knew 
how CW really works are either retired or dead.
73, Tom W8JI
W8JI@contesting.com