Troubleshooting Guide
This receiver will work as specified if the right parts are selected
and installed correctly and all connections are made as explained
in this manual . The #1 cause of problems in most kit projects is
exactly the things we tend to take for granted: a mistake or
broken wire in the connection of external items to the circuit
board, such as DC power, speaker, switches and so forth. After
that comes a mistake on the board itself, such as:
Incorrect part value
Reversed orientation of transistors, capacitors, etc.
Bad solder connection (cold joint or bridge)
If your receiver does not work, review ALL construction steps
carefully. Let somebody else go over your work and the steps.
Here is a guide to minor problems which are easier to solve:
1. Weak volume with headphones. Test your headphones on a
working stereo: it is easily possible for headphones to become
defective. Also, remember that the audio output is designed for
low impedance headphones (8 ohms typically) and poor results
might be expected from some high impedance magnetic phones.
2. CW signals all sound chirpy or wobbly.
The batteries are much too weak: check and replace.
3. Regeneration inoperative on some bands, especially Band 1 or
Band 9. Incorrect adjustment of trimmer R6. See Steps 7-51-54.
4. Receiver works fine sometimes, but is erratic especially when
it is bumped or moved. Look for a loose solder connection.
5. Very strong signals are impossible to tune in well.
Reduce the setting of the RF Gain control.
6. Signals wobble slightly if the receiver is bumped.
This is a normal characteristic of ANY simple oscillator.
7. The tuning bands seem mixed up, such as 80 and 20 meters
reversed. Incorrect installation of inductors: for example L2 for
80 meters is 33 μH (orange-orange-BLACK-gold) and L7 for 20
meters is 3.3 μH (orange-orange-GOLD-gold).
8. Extreme squealing or buzzing at higher settings of volume
control. This "feedback" indicates an error in kit assembly.
Recheck all assembly steps. (Slight feedback may begin to occur
with extremely weak batteries.)
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9. Erratic bandswitch operation; bands change when receiver is
bumped. The subpanel is mounted too lightly against the front
panel putting pressure on the switch. Move the subpanel as
needed to correct the problem.
Experimenting with 1253 Receiver Modifications
Radio amateurs and electronics hobbyists are just like car buffs
and many other hobbyists -- ever tinkering with and customizing
their equipment, regardless of whether it is factory-built or kit-
built. This was quite common in the decades before the typical
ham transceiver became an expensive, imported box tightly-
packed with sub-miniature components. We are well aware that
the roomy, straightforward design of the 1253 receiver virtually
invites creative tinkering and perhaps genuine enhancement.
We've seen enough magazine articles over the decades about
minor modification of TEN-TEC equipment to expect this. We
encourage you to make sure the receiver is working as designed
before trying any changes.
You may try building a power supply on the battery shelf in place
of the "C" cell holders. Be prepared for possible AC hum from
the transformer which no amount of filtering may solve. A better
approach could be an external wall transformer with proper
filtering built on the battery shelf. You may wish to change band
coverage characteristics by adding small-value (pF) capacitors in
the board positions conveniently provided for "C35-C42.'" You
may choose to replace the insulated antenna terminal assembly
with some sort of coaxial connector. Or, add an active antenna
circuit and telescoping whip for portability.
Please understand that chatting about modification ideas is
beyond the purpose of T-KIT Technical Assistance.
Conclusion
If you enjoy shortwave radio listening, you'll soon yearn for and
then get or build a more elaborate receiver. You might even
work on getting a ham radio license and setting up a station for
transmitting and receiving. As the years go by, we have a hunch
that you'll always remember the first thrills of building and
listening to your T-KIT 1253. And, because it's compact and far
more sophisticated than the first receivers of yesteryear, we
suspect you'll actually keep it and keep on listening to it when
nobody else is looking!
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