HRO-50

[tdavid]

some assistance with an HRO-50T1, please.  the "B" coil seems to work fine.   the general coverage alignment is fairly close but the 14.0-14.4 MHz tuning range is a huge problem.  the range of the coil is off so that if the oscillator is set correctly at 14.4 MHz, the calibration is off by 200+ KHz down at 14.2 MHz.   Also, the adjustments on the back of the coil doesn't seem to be accessible when it's installed in the receiver so i haven't touched them.

thanks!

Dave Cohen, N7TC

[WQ9E]

David,

Make sure you have it tracking on the proper side.  When the dial is set at 14.000 you should hear the oscillator at about 14.455 (dial plus IF frequency) in a nearby test receiver.  If it is on the wrong side you will find it at approximately 13.545.

Make sure that the .1 capacitor from one of the power supply rectifier plates to ground has been removed already.  If not remove it to prevent loss of your power transformer when it fails.

[KM1H]

Back side adjustments are to keep trying until it works, after a few hundred it sort of comes easier as you know which way to move the cap or coil loop and by how much.

Coils were factory pre tuned in a test jig and final alignment in the set to be shipped. Individual sale coils were done in a radio in the Service Dept.

Carl
KM1H
National Radio 1963-69