Blackcat JB-2000 10-11 meter, 10-80 meter, 6 meter

Blackcat made 3 major versions of the infamous 'JB-2000' linear amp:
The first version, the JB-2000 10-11.
The JB-2000 10-11 is a single band amplifier, dual 3-500z final tubes and a single 6CA7 driver tube. The 10-11 is single banded, 10-11 meters only, no band switch and has internal fixed Tune cap(s) and a variable Load tuner on the front. Hence, the 1011 is fairly sparce with adjustments on the front panel. No Bandswitch and no Tune adjustment. Early versions just had a power switch, standby switch, and a Load variable tune cap on the front. The single front Load adjustment was usually marked 'Tune' on the front panel. Amp also had a relative power output meter. Some later versions added a switch for the multimeter and then the meter could read Voltage, Amps, or Power. Some others added a variable Tune cap (as in Tune and Load) instead of the fixed Tune cap(s). There were many, many different variations on the 1011, the 1080 and 2006 too. The 1011 has a built-in driver tube, a 6CA7 tube which is an Octal audio tube and high-powered version of the 6L6 family. The 10-11 has a voltage doubler for the high voltage. It puts out around 2500v on the plate of the 500z's. It picks off at the halfway point of the doubler, which is around 1250v and runs it to the plate of the 6ca7 tube. 1250v is way too much volts for that tube and is killing it. Not to mention, they run 7.3v to the filament of the 6ca7. The 6ca7 is supposed to run 6.3v on the filaments and max operating HV is around 850v depending on the datasheet. Running up the HV and filament will make that tube talk all right. Probably doing around 150 watts out. However, its not going to be clean and the amp is just killing that tube. The JB-2000's with drivers were driver tube eaters, plus the power transformer was already undersized to run just the 500z's, but now has to run the voltages (plate, screen, filament and bias) for the 6ca7 driver too. The Heathkit SB-220 has around the same undersized HV transformer, but at least the Heathkit has a separate low voltage / filament transformer. The JB-2000's have only a single transformer that runs everything. Besides killing the driver tube, if you hit the JB-2000's, especially one's with the driver tube, hard and heavy, you will pop the undersized transformer. The 1011 is 4 watt drive (CB) and made exclusively for 10 and cough cough 11 meters. It also had a built in keying circuit, no foot switch. With the FCC crackdown in the mid 70's, a 4 watt drive amp that would work on CB was a No-no. Hence, next came the JB-2000 10-80 version.
With the FCC crackdown, the new FCC rule was no commercial selling of an amplifier that would work on 10 meters and have less than 100 watts drive. Hence during the time, commercially made Ham amps could have 10 meters, but had to be 100 watts drive. Hence, Blackcat remade the JB-2000 1011 into the JB-2000 10-80. The 1080 added the Ham Bands, 15, 20, 40 and 80 in addition to the 10 meter band. It also added a variable for the Tune cap instead of the 2 fixed caps the 1011 used. It got rid of the driver tube. No more 4 watt drive, and the amp now needed 100 watts give or take to drive it. Also, the 1080 got rid of the automatic keying circuit. Amp would now need a foot switch or a transceiver that had an output line that would key the amp. Other than the variable tuner, no driver and no keying circuit, the 10-11 and 10-80 are extremely similar. I have heard, but not confirmed that the 1011 ran the HV lower so they could tap the driver tube at half the HV. Since the 1080 has no driver, the HV was raised on the 1080. The 1080 is a better, more dependable amp than the 1011.
However, the CB boom was still in full effect, and the FCC swamped with CB TVI complaints, the FCC tightened the rules even further. The FCC just made it illegal to sell a 10 (11) meter amplifier period. Heathkit and others just eliminated 10 meters in their amps. Blackcat did the same (kinda) with the JB-2000's. Blackcat now retooled the 1080 and came out with the JB-2006. The 2006 was extremely similar to the original 10-11, but was sold as 6 meters only now. Looking at the schematics of the JB-2000 and the JB-20006, except for a few inconsequential part differences, they are identical. Back goes the driver tube, keying circuit, and mono band, but supposedly for 6 meters now. As the schematics don't show exact inductor specs, I cannot tell if it was really set up for 6 meters or not. I do not know the 6CA7's frequency response, but I do know the 6ca7 is an audio tube. Not made for RF and certainly not made for 6 meters (50-54mhz). It is said that audio and sweep tubes max limit is around 10 meters (29mhz). Hence, I believe the 2006 was '6 meters; in name only to get pass the FCC.