CW -- Something wierd
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CW -- Something wierd Expand / Collapse
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Posted Friday, July 11, 2008 5:15 PM
Supreme Being

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(PSDR 1.13.0 svn 2343, F5K, no atu, no rx2, win xp sp2, keyer primary - 5000, secondary none)

First let me say I am not a CW op, but out of curiosity, I plugged in my 20 year old Benchers into the back of the F5K.. At first, every thing appeared normal except I could not vary the keyer speed for the paddles.

I have followed the preceeding cw discussions on missed element etc. Looking at the schematic in the service manual, it looks to my like the 75468 inputs might be starved for current in the dash/dot input state. Anyway I started to try some things related when I stumbled into this...
If I momentarily touch a 1K resistor from the bencher DOT or DASH terminal to ground, I can sometimes cause the keyer to go into a continuouse string of DOTs or DASHs state even after the resistor is removed. (RF drive a zero, no RF out ) Touching the appropriate paddle kills the string.

I measure a key-up voltage of 2.31 volts and a key down current of 1.1 ma. With a 1K resistor DOT to ground, I measure 1.0 volts across the resistor and with the resistor removed I measure 2.31 volts while the DOTs are running!

I don't know if any one can reproduce this or what it might imply for the other CW problems,
but is sure seems like It could be related. It seems like the time constants of R7A/B C545/546 could take the inputs though the region of strangeness.

AL, K0VM


AL, K0VM
SDR-1000, Flex5000, Flex user since 2006
Post #1097
Posted Friday, July 18, 2008 1:43 AM
Junior Member

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Hi.

So far I have had no problems with a straight key but have just decided for the first time ever, to go iambic! Using a K8RA P2 at above 25wpm (and bungling some characters as I am not quite used to it yet) often results in the F5Ka staying in TX, keying strings of dots and dashes, which can only be stopped by hitting a dot or dash, as depending which string is being automatically sent, one paddle key won't break the TX cycle.

For the time being I have been forced to abandon the paddle on the F5Ka, reluctantly.

SDR v1.12.0 (not svn) and FW 1.2.0.3

Nige.
Post #1114
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