4-11. Set the RF Gain and both tuning controls to their middle
positions.
4-12. Slowly turn the Regeneration control clockwise until
you hear a sudden boost in background hiss, or a slight whistle
or actual signals. If this does not happen, proceed to step 4-14.
4-13. If you DID experience the effect of the Regeneration
control described in 4-12, you can now try the Main Tuning to
find various stations in the 6.8 to 8.5 MHz tuning range. You
may wish to study pages 49 and 51 regarding the functions of
the controls, particularly RF Gain and Regeneration.
4-14. If you did NOT experience regeneration as described in
4-12, an initial adjustment of trimmer R6 must be done with a
mini screwdriver or alignment blade. Procedure:
Turn Regeneration control to its middle position
Set R6 fully counter-clockwise
Adjust R6 slowly until the increased hiss or slight
whistle of regeneration just begins.
Turn Regeneration control fully counter-clockwise
and then advance it until regeneration just begins.
NOTE: It is normal for the rotation of R6 to generate loud
crackles and pops. Also, with the circuit board not mounted
inside the receiver cabinet, it is normal to hear some AC buzz
from nearby electrical wiring.
4-15. After you've finished exploring your one-band receiver,
disconnect DC power and speaker, and carefully unsolder the red
wire from the C37 pad near L4. This wire will soon be soldered
permanently to the Bandswitch control board.
1253 - 28
4-16, Preparation of
Main Tuning Knob
Probably, You never wondered or cared how those white stripes
happen to appear on radio knobs! well, they can be grooves
filled with paint, or silkscreened, or they can consist of a thin
wedge of colored plastic pressed into a slit on the side of the
knob. And, how does the setscrew get from the bin into the
knob? While these processes can be automated for truly huge
production runs, the painting of index stripes and insertion of set
screws is commonly done by hand, even in knob factories.
We provided this economical receiver kit with the very same
made-by-TEN-TEC Main Tuning knob designed for our Model 555
Scout HF transceiver and the T-KIT 1220 VHF transceiver. Since
those applications do not require any marking on the main tuning
knob, we invite our other kit builders to taste the sheer fun of
how easy it is to place a neat index stripe on ANY knob with
molded grooves. After you try it, you may want to freshen up
the index stripes on the knobs of every radio or electronic gadget
in your household or shop!
With a small arts/crafts brush or even a Q-tip, paint a drop of
WATER-based (latex or acrylic) enamel into one groove of the
main tuning knob. Don't worry if some paint is left on the outer
rim of the knob outside the grove. Let the paint dry about 10
minutes, then try cleaning off any excess paint outside the
grove with a DRY smooth cloth or paper towel. If necessary,
moisten the towel very slightly to help dissolve unwanted paint-
traces. Rub patiently. The result should be a uniform coating of
paint within one groove on the side of the knob.
If you used a water-based paint and did a lousy job, don't worry
at all. Promptly use a wet rag or toothbrush to scrub out the
paint: rinse the knob, dry it and try the painting again.
We suggest water-based paint simply because there's no way
that using water as a solvent or cleaner can damage the knob
itself. If you have other skills and experience with art or model-
finishing, just use the paint and techniques most familiar to you.
4-17. Use a #4 Allen wrench to insert and secure the
supplied allen-type #4-40 set-screw into the tuning knob. This
same size wrench is also used to tighten ALL knob setscrews.
1253 - 29
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