Original models covered 160/80/40/20/15/11/10 metres. Originally available in kit or factory wired form. Later, the Ranger 2 dropped 11 metres and added six metres.
There were several circuit changes over the years which are covered in the better modification text. The E.F. Johnson Ranger is one of the easiest plate modulated transmitters to use as a source of R.F. for either a linear amplifier or a high power plate modulated rig.
Designed as a driver for the Johnson Desk Kilowatt, the Ranger quickly became popular as a stand-alone unit with room for expansion. There are stories of Johnson employees assembling some units at home after normal working hours to keep up with the instant demand.
Good points:
Nice size. Can be carried and lifted on a shelf without permanant damage to station personell without wearing an athletic supporter.
The layout lends itself to easy modification and repair except for the VFO section. Uses commonly available parts which are not difficult to obtain during repair. Has no built-in grenade high failure major components. The plate and modulation transformers hold up fine when not abused.
Easily the best sounding audio before modification of any commonly available ham plate modulated transmitter. Effective TVI supression which is even better than some of the holy grail brand rigs of several years earlier. Has rear panel mounted accessory plug which makes interface with a homebrew "big rig" very easy.
One of the few hammy storebought AM transmitters that use inverse feedback around the modulator section. This is an absolute must when using a tetrode or pentode power audio amplifier driving a pair of triodes into grid current. Easily modified for lower carrier output required when driving linear amplifiers.
Downside:
The VFO will sooner or later need the infamous 18K resistor repair.
I recommend changing most other resistors in there due to the labor involved in getting to these components. Originally a hodgepodge of questionable engineering. All stock units waste enough power in standby to fry enough eggs for the whole family. The factory or retrofit T/R can be very confusing. Fortunately, well thought out, tested modifications are easy to find. Be wary of picking and choosing sections of these modifications as results will be dismal unless all suggestions are followed!
Always look for modifications with the registered Timtron trademark. Others can be considered at your own risk. What to look for when buying: Look for examples which have the built-in T/R circuitry as the mode switch can be quite warn out if used as the T/R switch. If the extra T/R parts are not there then take a close look at the mode switch contacts. Also look for units that have flexible wiring. There are some that have had heavy use and all the harness wiring is ready to crumble!
Look for Rangers that have been hacked to work on the CB freeband. Repair items that can drive you nuts: Watch for rivited 6146 final tube socket. Poor connection to ground at the socket will cause final problems that apear as poor neutralization. Not all Rangers use rivits and some nut and bolt units are failing also.
Most often mis-modification:
Reducing output power when driving a linear amplifier through the use of a T connection and a dummy load and/or reducing loading or screen Voltage. This situation wastes one of this rig's better resources namely modulator headroom. When altering the R.F. final's impedance through reduced plate current, the modulation transformer no longer sees the designed load.
The correct way to reduce output power is to use an external plate supply with a Variac on the primary or switch the low B+ Voltage to the final (removing the high B+) through the accessory jack. Either way the high B+ is left on the modulators. This gives an immediate improvement to the audio as the modulator requirements are now cut way down without forcing the modulator into an unknown load. With the accessory low power mod, the rig will put out abour 12-14 Watts carrier which is a good level for driving quitea few linear amplifiers. Every available effort to clean up audio distortion should be considered when runnung QRO AM!
Excellent article. You really don't need the Timtron mod. Simply replace the filter capacitors and do the basic safety/longevity modifications and tube replacents and you'll have a nice Ranger with plenty of necessary punch to do the work. Don't have the punch? Stick a linear amplifier and tune it for 1/4 of the PEP power output.
E.F. Johnson Ranger
