[Novice-Rigs] EICO 717 Electronic Keyer: EPILOGUE

[Edward Swynar]

Hi Again All,

Many thanks for the many personal notes that I've received from you all in
the matter of the EICO 717 electronic keyer...interesting that MORE than a
few of you have gone on record as saying the 717 was not worth the effort of
assembling, in that it never did work right! Hi Hi.

Well, I've had my share of travails here with mine, too, make no mistake
about it...however, I really & truly do believe that any inherent oddities
that came with the keyer that I acquired earlier this year have finally been
"cured".

For those who may still have an EICO 717 sitting forlornly and unused on a
shelf, please try these fixes BEFORE you completely give-up on the thing. I
can honestly tell you they worked for me!

(1) As mentioned in a previous posting, the keyer benefited from an
"...RFI-proofing" retrofit that consisted of nothing more elaborate than
series-installed 2.5-mh. RF chokes in the output key terminal, & in the dot
& dash input terminals. These chokes were in turn all bypassed with
0.001-ufd. disk ceramic capacitors to ground, as well, right at the each
terminal. Additionally, the AC power cord leads were bypassed to ground with
0.001-ufd. caps at their entry points to the keyer chassis.

(2) Also mentioned earlier was the fact that the problems of initial dot
"contact bounce"  effect, and an inordinately long initial dash, were both
cured by directly replacing V4---the 12AU7 dot multivibrator---with a 12AX7.

(3) If your keyer sends "mixed" characters mid-stream, replace V3---the
12AU7 master oscillator---with a 12AX7.

(4) If this latter swap doesn't "clean-up" the keyer's mid-stream character
formation, look at the heptode portion of V2, i.e. the ECH81 "keyer tube". I
found with my 717 that the ideal ECH81 in this stage is one that is
relatively weak. Specifically, by using an ECH81 with a measured
transconductance of 1500-mhos., the problem of mixed-up character formation
was cured. By contrast & for confirmation, I temporarily subbed-in an ECH81
with a transconductance of 3175-mhos., & the issue returned---with a
vengeance. Even a tube displaying 1780-mhos. was essentially unuseable in
this application.

If your junque box yields no replacement ECH81's, try simply swapping the
positions of the two already in your keyer. If that doesn't work, begin the
hunt for a 6AJ8 tube, which is listed as being a direct American replacement
for the ECH81 tube (why EICO elected to use these tubes is a mystery to
me...musta been a "good idea at the time"! Hi Hi).

The July 1967 QST Product Review was of little assistance in regard to my
keyer here: the write-up quotes a total of 9 tubes in the 717---mine only
has 6. I can only surmise that EICO made changes in the design of the keyer,
& that I have either a newer, or older, example than the one described (the
serial number of mine is 140-09-9959).

The only issue with this keyer now is one of operator error: I've become so
very spoiled by the modern-day built-in electronic keyers in my Yaesus &
Icoms---what with their buffer memories that allow me to actually "lead" the
keyer, and all---that I continue to make errors in my character formation
that are due to my own personal sloppiness! Old habits are hard to break,
alright, but I'm attempting to do just that, right now, as I mate the 717
with a pair of Drake Twins here in my back-up station, & make QSOs on 40-
and 160-meters...

The moral of all this...? Do NOT give-up on that EICO 717! There is life
remaining in that ol' buggy yet...and all it needs is some TLC to bring it
back to an active position within your shack!

~73~ de Eddy VE3CUI - VE3XZ