[Elecraft] K1-4, Receiver Alignment, adjust AF gain, hear "NO" background noise

[Stuart Rohre]

Andy  made a great call on noting that mono phones will short out the K2
phone jack, which is stereo connected like some other rigs today.

This is a good lesson for all builders, before starting a project, read thru
the manual and note the specs for accessory items you will need to test/
operate the radio, (kit or ready built).  Make sure you have the appropriate
phones, with stereo or mono type as needed, of the correct impedance, or
compatible, and make sure you have the key, paddles, mike or whatever with
the correct plug to fit the project at hand.  On mikes, some need power
supplied to them and some do not. Older mikes were designed to operate into
higher impedance circuits than modern mikes of the computer types, and thus
you may need an accessory mike matching transformer.  Some mikes have pre
mounted plugs and some radios do have differing plug pin configurations and
numbers of pins.  Radios have gone from two conductor mike jacks to three,
and now we see many kinds, 8 pin or 4 pin or other variations including
telephone like RJ connectors.

Also, make sure you have the exact matching power connector.  Examples of
close but not correct include the Ten Tec Scout needs and AMP made
connector, slightly different from Radio Shack common Molex types.  The K2
needs a specific coaxial power DC connector, and those now come in a variety
of sizes and ratings.

In other areas, (rigs that needed external crystals), you must know the type
circuit the crystal is specified in, (series or parallel resonant) at some
specified capacitance, for a crystal house order to match your radio to the
frequency you order.

In power supplies, you need a supply to test a radio that is not only
typically 13.8 volts or at least 12, but also you need more amperes
available in the supply than the radio draws to not starve the circuits.  If
using a battery, make sure it is fully charged, and has low self impedance.
Very old Gel Cells will get to a point of not holding charge and because of
increased self impedance can cause induced problems to a new circuit, such
as oscillations, that would not be there with a stiff and full
voltage/current supply.

72, Stuart K5KVH