-- o ICOM

------------------------ 1
continued from p. 76
AU of us have at least slig htly
different perspectives on these
things.
If you're worki ng on a homebrew
project and can't seem to
get it to operate quite right. drop
a line 10 the author . There may
be a spider or two that got into
the article . II you do write, please,
by all mean s. send an SASE
for your reply. I know from firsthand
experienc e met those
who send an SAS E will get a reply
quicker than those who don't.
In your home-brew project, again,
look everything over closely.
Be espe cially picky about the
proper pin outs of tran sistors,
res, and other act ive devices.
Next. check for the prope r polarity
of the electrolytic capacitors.
Those critters just don't work it
they're installed backwards. l ook
over the values of the resistors.
It's so easy 10 transpose a 1kO
resistor lor a 10kO resistor at 2
o'clock in the morning,
To Tweak or Not To Tweak
II yo u' re working on a commercial
product , whatever you
do, don't get out the diddle sticks
and start messing with Ihe alignment!
I've never seen a piece
of equipment stop working because
the alignment went bad ,
unless someone diddled with
it first . Don't diddle unless you
really know what you ' re doing.
There is one exception­
Heathkit gear. If you can't seem
to get one working as it should,
then do an alignment. Most
Heathkits c an be aligned with
" .. most
failures occur because
ofheat. "
simple lools, sometimes using
nothing but the radio itself. You
can sometimes pinpoint trouble
by going through the alignment
on Heath gear. Finding a stage
that will not peak up as it should
will give you a starting point
for more serious troubleshooting.
But again, don't diddle with the
alig nment of non-Heath g ear.
We'll look at some more troubleshooting
guides later on this
year.
Ten-Tee Mod
I want to thank all 01 those who
sent me information on converting
the Ten-Tee Century 21 lor tz vctt
operation. For all those who wrote
in to me, thanks! For the rest of the
gang, here is the modilication lor
12 volt operation.
First, you'll need a magnetic circuit
breaker lor the 21. This is Ten­
Tee part number 1170. Since the
protective circuitry lor the PA transistors
in the Century 21 is included
in the internal power supply,
you must use the circuit breaker
when runn ing the21 from tzvcns.
After you obtain the magnetic
breaker, apply 12 volts to the 21
via one of the AUX 12 VDC phono
jacks on the rear apron 01 the Century
21.
Doing trns. however, makes
th e Iront panel wattmeter inactive
(while on external 12 volts
only). To adjust fo r full power,
turn up the drive until the breaker
trips, reduce the drive a tad, and
reset the circuit breaker. You're
au set to fly this month for Fietd
Day!
Speaking of Field Day, I sure
hope that you guys send in some
photos this year. It's been slim input
from the QAP operators on the
subjeet of Field Day. Sure could
use some good photos. If you like
what you see, then by all means
drop a line to the editors.
For those of you who just can't
get enough solder smoke in your
face, I've got some modificatiOns
to the Two-Fer. These modifications
are by Don Garrett
WA9TGT. The mods make lor better
output filtering, full QSK, automatic
antenna switch ing, high
SWA protection, and power output
adjustment. The t z vott line on
the oscillator has been moved to
the colleetor of 04.
This keys the oscillator alOng
with the PA and buffer amplifier.
Since there is not enough room
this month for the mods, those
wishing to get a copy should send
me an SASE. I'll send you out two
da ta sheets for the modifications.
No SASE, no data!
Don't forget Field Day this
month. Watch for openings on ten
meters. Should prove to be a lot of
tun! fJJ
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