G'evening bro 🤠 . I've been a little sidetracked lately. My wife and I just moved 2600 miles from Idaho to Florida. On the flip side of that coin I just picked up a new to me Galaxy DX 959 radio & a 2 tube "no name" linear that was made by Chris aka Stickman outta MD before he passed away a few years ago & it should be plenty for what I want to do with this galaxy 🙃 ..
Question, I recently purchased what looks like a blackcat JB12 modulator, it has 8 diodes in the power supply and my issue is that the bleed resistors are getting very hot and want to smoke at only 60 volts. The caps and resistors are new and the tube tests good, any thoughts?
You have something very very wrong. The bleeders go across the High Voltage capacitors and should have about 350v across each bleeder/cap. They run warn but should not get hot. Do you have the right resistance (ohms) on the bleeders? On some Blackcat JB-12 and JB-150 schematics the bleeder resistor is mis-labeled. Th schematic has 10k resistors where the actual resistor needed is 100k. Using Ohms law, a 10K across that cap would pull about 11 watts which is what sounds like your problem is. Use 100k resistors, at least 2 watt, but I personally go with 3 watt flameproof resistors.
It will load for 10-15 meters including the Ham WARC 12 meter band. Yes, ground the grids directly, get rid of the 120 Bias, use a dropping resistor in the cathode and a diode string for operational bias and enjoy.
Very clean layout. It seems more thought out. 😎
Clean layout, short connections, good components, that is why the Drake L4b and L7 are considered among the best 3-500z boxes made.
G'evening bro 🤠 . I've been a little sidetracked lately. My wife and I just moved 2600 miles from Idaho to Florida. On the flip side of that coin I just picked up a new to me Galaxy DX 959 radio & a 2 tube "no name" linear that was made by Chris aka Stickman outta MD before he passed away a few years ago & it should be plenty for what I want to do with this galaxy 🙃 ..
Sounds like a nice driver.
Question, I recently purchased what looks like a blackcat JB12 modulator, it has 8 diodes in the power supply and my issue is that the bleed resistors are getting very hot and want to smoke at only 60 volts. The caps and resistors are new and the tube tests good, any thoughts?
You have something very very wrong. The bleeders go across the High Voltage capacitors and should have about 350v across each bleeder/cap. They run warn but should not get hot. Do you have the right resistance (ohms) on the bleeders? On some Blackcat JB-12 and JB-150 schematics the bleeder resistor is mis-labeled. Th schematic has 10k resistors where the actual resistor needed is 100k. Using Ohms law, a 10K across that cap would pull about 11 watts which is what sounds like your problem is. Use 100k resistors, at least 2 watt, but I personally go with 3 watt flameproof resistors.
@@tramdr Would a 100K, 5W white rectangular ceramic resistor also work?
sure
@@tramdr FYI, I installed the 100K 5 watt ceramic high power resistors in the JB12, no smoke or discoloration but they do get hot?
Maybe a little warm but not hot. You got them in right, in series across each cap and not in parallel?
“Mono banded for 10 through 15 meters” you might get it to work on 11 meters but that’s illegal.
Doc, do you recommend grounding the grids on an L4B?
It will load for 10-15 meters including the Ham WARC 12 meter band. Yes, ground the grids directly, get rid of the 120 Bias, use a dropping resistor in the cathode and a diode string for operational bias and enjoy.
@@tramdr Thanks Buddy.
i have some really clean stuff.
You do? Cool, show it.