k5mke
05-25-2005, 07:35 PM
Some of you may remember the old E.F. Johnson Whiteface CB transciever or it's brother, the Blackface. These were 5 & 10 xtal-controled AM rigs.
The Blackface also had a 23-channel receive VFO as well.
Modifying these radios is almost painless and can be put on the 10 meter AM band (29.000 to 29.200 mcs).
The mods are fairly simmple. Look for the Final, the 7061, locate the screen resistor. Remove any jumper or low value resistor, unless it's a 390 ohm, 10 watt sand power resistor. Parallel that resistor with a .27mfd 600 wvdc mylar capacitor. ($2.50)
Then, remove the rectifier tube, not the vibrator, the rectifier tube very back one, by the power transformer. You can hard wire a full-wave diode bridge made up of 4 - 600v/1A diodes to each of the correct pins.
This will allow your B+ to go from 375vdc to about 550wvdc. With the final screen tuned circuit the rig will dead key about 25 watts but upon a good modulating tone, the carrier will rise significantly or modulate upward, hehehehehe.
The only thing left to do is to purchase some xtals for 29.000, 29.025, and other frequencies you wish to talk on.
The cost of the crystals are $19.95 apiece from I.C.M. (International Crystals, Okla. City, OK.) They are 3rd overtone in a HC6/U configuration with hard wire pins.
This and the Blackface use modulation similar to the Heising and will give a good account for audio and your station reports.
I have a working one on 29.025 (National calling channel) and 29.101.0mcs ("29. 10-10")
I'm on 10m AM on the weekends.
Respectfully,
'73,
Buck/K5-MKE
3885kcs, where AM is still Alive!
The Blackface also had a 23-channel receive VFO as well.
Modifying these radios is almost painless and can be put on the 10 meter AM band (29.000 to 29.200 mcs).
The mods are fairly simmple. Look for the Final, the 7061, locate the screen resistor. Remove any jumper or low value resistor, unless it's a 390 ohm, 10 watt sand power resistor. Parallel that resistor with a .27mfd 600 wvdc mylar capacitor. ($2.50)
Then, remove the rectifier tube, not the vibrator, the rectifier tube very back one, by the power transformer. You can hard wire a full-wave diode bridge made up of 4 - 600v/1A diodes to each of the correct pins.
This will allow your B+ to go from 375vdc to about 550wvdc. With the final screen tuned circuit the rig will dead key about 25 watts but upon a good modulating tone, the carrier will rise significantly or modulate upward, hehehehehe.
The only thing left to do is to purchase some xtals for 29.000, 29.025, and other frequencies you wish to talk on.
The cost of the crystals are $19.95 apiece from I.C.M. (International Crystals, Okla. City, OK.) They are 3rd overtone in a HC6/U configuration with hard wire pins.
This and the Blackface use modulation similar to the Heising and will give a good account for audio and your station reports.
I have a working one on 29.025 (National calling channel) and 29.101.0mcs ("29. 10-10")
I'm on 10m AM on the weekends.
Respectfully,
'73,
Buck/K5-MKE
3885kcs, where AM is still Alive!