The AM Forum

I recently purchased a Johnson Ranger and am presently going through the schematics -- it appears to be an "early" version as it so far corresponds to the early schematic listed on Bama.  The unit is in original condition with no mods (outside a PTT switch added on the chasis).   My first step will be replacing the original  electrolytics, any out of tolerance resistors, and cleaning out 1lb of cat hair!

Near the function switch, there is a .02uf capacitor (C76) and a carbon resistor (R34) in series.  I believe R34 should be 2.2K ohms (the color bands are worn); the resistor is open and needs replacing.  The "early" schematic indicates R34 should be 220 ohms.  It appears to be original, but I'm not entirely sure.  Is the schematic correct? 

My early version schematic and parts list indicate R34 is 220 ohms. In the later version schematic, that RC network (.02 uf cap. and 220 ohm resistor) is not used.

Thank you for the quick reply!  I swear it looks like red-red-red (2.2K ohms), but I guess the 3rd band should be brown.   I'll go with 220 ohms according to the schematic.

Also, what are the primary differences between the early and later versions of the Ranger?

Keyer and bias circuitry were integrated into the circuitry. There were also component and wiring changes made. No visible changes to the front panel.

Original Ranger schematic, the first one (or at least the one I have), is dated Jan. 1954. The schematic had a revision 11/5/54 and another in 10/17/57. The November 1954 revision included the keyer and bias circuitry integration.

You will also note a difference in the wiring of the function switch between the old and new version of the Ranger. Once you have your Ranger running you will probably notice a popping noise when switching the transmitter off, if your function switch has the old version of wiring. If you have it out of the case you will see an arc at the switch contacts which is what is causing the popping noise. There is a well known fix out there that cures this problem by wiring the function switch the same as the later model Ranger, I did this on mine and it worked well. Note the funtion switch itself is the same between old and new versions of the Ranger only the wiring to the contacts has been rearranged. Search the archives on the Johnson list on QTH.COM to find the step by step instructions for doing this. One of the common upgrades a new Ranger owner does is to replace the filter caps with new ones of greater capacitance, it was my fear that the upgraded storage capacity of the larger filter caps would rapidly destroy the affected function switch contacts if I didn't do this fix.

I appreciate the information -- I'll definitely look into the function switch fix! 

Thank you to everyone!

Chris