Ramsey Electronics HR30 Instruction Manual - page 19
HR30
•
19
PROBLEM: Oscillator inoperative or wrong frequency.
SOLUTION: In addition to checking solder joints, be sure that L1 is
oriented correctly and that C1, C2, C3 and C4 are installed in
correct positions.
PROBLEM: Loud AC hum or buzz.
SOLUTION: If you are using the receiver with a battery or simply for listening
(i.e.: not connected to a transmitter or a AC power adapter),
these are likely causes of the AC hum:
•
No ground connection.
•
Receiver located too close to an AC device such as an older
electric clock, AC-powered radio, etc.
•
Antenna very close to a power cord or house wiring. If your
receiver is being used with a transmitter, the transmitter power
supply may be the source of the unwanted AC hum. If you are
using a 9-volt AC power adapter, the adapter design may not be
of sufficient quality for this application. Try a bypass capacitor, or
a different adapter or a well-designed and filtered DC power
supply.
A careful check of all construction WILL solve you problem. Over 95% of the
kits returned for repair have nothing more than a simple assembly or
construction error!
GENERAL NOTES FOR EXPERIENCED QRP BUILDERS:
We at Ramsey Electronics deliberately designed the HR-series of DC
receivers to be easily available, affordable and buildable by any person willing
to follow the assembly directions. To achieve this goal, the current models,
with direct coupling of the SA602 to the LM386 operating with a gain figure of
50, use an amazing minimum of parts. If you know what you are doing with
DC receiver design, we encourage you to use our HR-series for reliable
building blocks for achieving maximum performance for your own application.
If a good idea does not work as expected, you can easily restore your Ramsey
receiver to its original circuit configuration.
Our job has been to keep in stock for immediate delivery a good basic design,
a quality PC board with plenty of work room, useful front panel controls,
correct and adjustable inductors, workable varactor tuning and the popular
SA602. We know these receivers WORK, as specified, and that the ONLY
reason any HR-receiver will not work after the 1-2 hours needed for assembly
is if we packed the wrong parts or you put them in wrong. Once you are sure
the receiver performs as specified, there is a lot you can do to coax maximum
performance from the basic circuit.