[R-390] Carrier meter PCBs available.

[Bob Weiss]

I have had a few folks contact me about the carrier meter amp PCBs I 
made for my 390A restoration. The remaining units quickly sold, so I had 
an additional run of the boards made, and am still offering them at $20 
per board, plus $5 shipping in US.

This is a 1.5" diameter round PCB which allows a standard high 
resistance meter to work and achieve proper deflection with the 
unusually low impedance requirement of the 390 meter bridge circuit.  It 
uses an operational amplifier as a current sense amplifier, with a 18 
ohm shunt resistor to duplicate the original meter resistance.  Requires 
2 additional wires to power the amplifier, connected to the AC heater 
supply and ground.  Board comes completely assembled and tested, you 
supply the meter (practically any low range DC 
milliammeter/microammeter), and you will need to select and install a 
calibration resistor for it. Installation instructions and schematic 
included.

Picture of the board available at:

https://www.flickr.com/photos/140826987@N07/

Payment via paypal, or snail mail to QRZ address.

73,

Bob Weiss N2IXK