Wensday I just inharitated an "National Panasonic" DR28 solid state radio:
http://www.transistor.org/collection/national/nationalpanasonicDR28.jpg
http://universal-radio.com/catalog/portable/dr28.html
What are use for S.W. 2~4 CAL, M.W./S.W. R.F. Gain, Pitch (On/Off)?

An excellent radio that I had always wanted! :yes:
1. Not quite sure what the S.W. 2~4 CAL refers to. There is a Calibration switch that activates an internal crystal oscillator every 125kHz or so so that the analog mechanical drum dial on the left can be adjusted to match the digital display on the right.
2. The MW/SW RF Gain control lets you adjust the external antenna input in case strong signals from 550kHz to 30MHz overload the radio.
3. The Pitch control is for listening to SSB signals (Single Side Band). Amateur radio, marine weather, ship-to-shore telephone, etc. use this method of modulation instead of Amplitude Modulation signals.

It uses Germaniun or Sylicum tranzistors?

Mine (http://www.proradioantic.ro/index.php?x=item&id_p=396)

[QUOTE=OvenMaster;1280791]An excellent radio that I had always wanted! :yes:
1. Not quite sure what the S.W. 2~4 CAL refers to. There is a Calibration switch that activates an internal crystal oscillator every 125kHz or so so that the analog mechanical drum dial on the left can be adjusted to match the digital display on the right.
QUOTE]

The SW 2-4 CAL tweeks the second oscillator a little so that the frequency indicator is right on. Tune to WWV at 10.000 or some other station that you know the exact frequency of. If the display is off, say at 9.997 then tune until it says 10.000 and tweek the CAL knob until it sounds center tuned.

My 2600 has the same feature. Both are nice sets.
Analog tuning + digital frequency readout = Bliss!

David

Methinks you got a DANDY nice radio, there, Pal !