Prototype National NC-303 Receiver?
NC-303 in an NC-300 Chassis
Don K1JQ sent me info on his recently acquired NC-303 for my NC-300 &
I was confused because it was an NC-300 serial number (481-1927) but looked like
This is a REALLY INTERESTING receiver!
It is hard to believe that it is just some ham's conversion - there are too
many changes and that just doesn't make sense.
So perhaps it is an NC-303 engineering prototype that was built on an NC-300
Some things I have noticed -
- 481-1927 is the last NC-300 chassis number known, so it makes sense it
could be used for engineering rather than production.
- The front panel is NC-300 (note cutout above CAL knob), but without NC-300
markings and with NC-303 markings.
- The bezel and knobs are NC-303, obviously
- The NC-303's vernier drive was not added (the hole also appears in late
NC-300 front panels)
- The cabinet is NC-300, not NC-303.
- Don acquired the receiver from someone not far from Malden, Mass.
- The NC-303's Q-multiplier with 12AX7 (V15) has been installed (as in the
- The NC-303's additional 1st mixer transformer (T3) has been installed (as
in the NC-303 production).
- To make room for T3, the S-meter adjust pot has been relocated (as in the
- To make room for the S-meter pot, the 4H4 socket has been relocated (as in
the NC-303 production)
- The 6AL5 (V14) socket has been added (as in the NC-303 production).
- And what ham would use rivets rather than nuts/bolts? Hard to use
rivets unless you started with a bare chassis?
- To make room for the XCU-303 WWV calibrator, the calibrator socket has
been relocated toward the 6AQ5 (as in the NC-303 production).
- To make room for the calibrator socket and 6AL5 socket, the audio
transformer has been relocated to mount on the rear (as in the NC-303 production),
- To make room for the audio transformer, the speaker terminals have
been relocated to the NC-300 AC line cord location (as in the NC-303
- To make room for the speaker terminals, the AC line cord has been
relocated to the NC-300 fuseholder location (as in the NC-303
- To make room for the line cord, the fuseholder has been relocated to near
the 4H4 (as in the NC-303 production)
- The co-ax antenna connector has been added
- To make room for the co-ax connector, the antenna terminal strip has been
- Summary - the Q-multiplier, T3, co-ax connector, and 6AL5 V14 were added.
The calibrator socket, audio transformer, speaker terminals, antenna
terminals, AC line cord, fuseholder, 4H4 socket, and S-meter pot were all
relocated to the same locations as in production NC-303 units.
- Boy, that was a lot of work!