Cool...
I've had mine since it was new...use it now and again but it has
developed the extra dit issue as many of these has. I am going to try
this fix.
Just picked up a Hallicrafters TO keyer for the vintage desk also. Same
keyer basically.
Curt
KU8L
On 1/1/2012 1:59 PM, Eddy Swynar wrote:
*/Hi Guys,/*
To-day I just discovered something that is specific to the old /EICO
Model 717 /electronic keyer---but it just */could/* be applicable to
any other gear in your possession that utilizes a field coil / reed
relay to accomplish rapid circuit switching...
Anyway, FWIW---/delete if uninterested.../
I found that the keying characteristics of the internal audio
oscillator in this vintage tube-type keyer followed that of the
mechanical keying mechanism very well: however, the external device
being keyed displayed a noticeably truncated first dit---almost a
contact bounce effect. The circuitry of the /717/in this application
utilizes an ultra-miniature reed relay to key one's rig---the relay is
located right in the middle of a field coil that activates it.
I found with my keyer that the location of the relay inside the coil
was haphazard, at best---plenty of room to "float"---and so I
experimented with moving the relay through the length of the coil, to
see what effect, if any, this might have on the make of the first dit.
I found that (obviously) moving the relay too far /OUT/of the field
coil stopped the keying process entirely. However, moving it too far
/INTO/the coil merely exaggerated the "bounce" effect...
I finally located the relay so that about 1/4" of it extended
*/OUTSIDE/*of the field coil itself---and I'm very happy to proclaim
that the keying is perfect now.
Previous to this "discovery", I had swapped & subbed tube after tube n
the circuit, with various degrees of success. In hindsight, I can see
now that any "good" or "bad" effects were most likely induced by the
relay/coil moving fore/aft of one another during the process of my
removing the keyer from its enclosure!
To guard against any future such variables, I applied two blobs of
silicone sealant to the coil, bonding each end to the
chassis...hopefully this will forever preserve "...the sweet spot" of
the location betwixt these two components...
*/~73~ de Eddy VE3CUI - VE3XZ/*
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
_______________________________________________
Drakelist mailing list
Drakelist@zerobeat.net
http://mailman.zerobeat.net/mailman/listinfo/drakelist
