K2 K3 Cleaning; Non-Standard Relay Replacement - Hallicrafters SR-150 Operation And Maintenance Manual

3-5-2. K2 K3 CLEANING:

Spray strip of paper with DeOxit, insert it between the NO contacts, compress the armature and pull the paper,
repeat several times.
Spray strip of paper with DeOxit, Insert it between the NC contacts, pull the paper and repeat several times.

3-5-3. NON-STANDARD RELAY REPLACEMENT

If it turns out that only one of the original relays is salvageable you may want to consider the following.
Warning this modification should be undertaken only by an experienced technician. A moderate level of skill in
reading schematics and tracing ckt wiring is required. Install the working original relay in the K2 position. Find
a suitable 12 VDC relay and install it for K3. We will pick up 12.6vac from the filament line rectify it, filter it
and connect it to one end of the replacement relay coil. Place a reverse diode across the coil. The other end of
the coil will connect to the unused, grounded in receive mode terminal of K1. All of the components, with the
exception of the resistor, can be mounted on one 4 contact terminal strip and mounted anyplace that pleases you
By Walter Cates WD0GOF (UPDATE 10/30/2013) 27