-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Black Cat Amplifier
- Thread starter oil2gas
- Start date
Toll_Free
Well-Known Member
Toll_Free
Well-Known Member
No, they really do pull about 300 watts peak from the power supply. It IS a wattage number, most CBers are just not educated as to the difference between input and output power.
Hence them believing an SB220 should swing to 2 grand, as well.
--Toll_Free
Toll_Free
Well-Known Member
That's a statement that doesn't make any sense..... Even if you're talking about it at 50 ohms, it's only 1250 watts of RF output. 1500 is the legal limit.
I can measure my 4CX5000A output amplifier with a 5A meter, too. Of course, I'm only putting 5 amps into a 600 ohm ladder line.
5 amps at 600 ohms is 15 grand output. 5 amps at 50 ohms is only 1250.
Stating your amplifier makes 5 amps is a worthless number, since it's not referenced to anything. Is that into a dummy load, a reactive load, etc?
I'm NOT trying to be an ass here, I know what you're saying, I believe, I just want OTHER people who might pull up this thread in the future to realize, just because you can state ONE number doesn't mean anything.
5 amps of RF can be 100 watts, 1000 watts, 15,000 watts or 150,000 watts. You need to know either the voltage at that point, or the TRUE resistance (or 'normalized resistance', which is a complex math formula to get there, but it basically takes the R (+/-) j and turns it into a straight R number, so you can plug it into ohms law and get a reading.
I hope that helps people understand. The OTHER thing that matters is that an AMMETER is ONLY accurate at 50 ohms. As SOON as you enter any reactance, it requires a lot of math to figure out where you're REALLY at. That means, if you move the ammeter (just like an SWR meter) in the feedline, you can change the amount of RF amps it shows... IE, in my 600 ohm feeders, I can move the ammeter 20 feet in either direction, and it will show BIG differences in the induced current: Which makes sense, an Ammeter is ONLY a voltmeter calibrated across a known precision value shunt.
--Toll_Free
Everyone in the world uses an amplifier normalized into 50 ohms. Every type accepted ham amp made is 50 ohms source impedance. Same for every radio.
This isn't 1945.
I said a little over 5 amps. Please read carefully net time. Even less than 5 amps steady state can be 1500 watts P.E.P. on amps with marginal headroom. Since an Rf ammeter will not show fast peaks one experienced with this device will assume carrier conditions.
I'm not trying to be anything here. Just sayin'
An rf ammeter ignores reactance so scratch that off the list.
If your running 600 ohm feeders and are not terminating them with 600 ohms YOUR 5 amp reading is not going to tell much about power out. Almost nobody used 600 ohm transmission line terminated by 600 ohms. Do you? Your tuner matches the antenna system, not the feedline.
What the heck is TRUE resistance. The word true is pretty scary. Are you talking about the resistive portion of an impedance. What formula. Yes, it must be complicated.
You only have a 4CX5000?
This isn't 1945.
I said a little over 5 amps. Please read carefully net time. Even less than 5 amps steady state can be 1500 watts P.E.P. on amps with marginal headroom. Since an Rf ammeter will not show fast peaks one experienced with this device will assume carrier conditions.
I'm not trying to be anything here. Just sayin'
An rf ammeter ignores reactance so scratch that off the list.
If your running 600 ohm feeders and are not terminating them with 600 ohms YOUR 5 amp reading is not going to tell much about power out. Almost nobody used 600 ohm transmission line terminated by 600 ohms. Do you? Your tuner matches the antenna system, not the feedline.
What the heck is TRUE resistance. The word true is pretty scary. Are you talking about the resistive portion of an impedance. What formula. Yes, it must be complicated.
You only have a 4CX5000?
Toll_Free
Well-Known Member
1. Not everyone uses 50 ohm stuff. CBers use 50 ohm stuff, lots of appliance operators use it, and people lucky enough to have the $$$s to put up a resonant antenna for every band, then coax feed it... Or those lucky enough for the property, etc. Myself, I'm lucky enough to have 11 acres, so I play with all KINDS of antennas. As such, OWL works BEST for me, since I don't have to worry about building a matching network. I know of PLENTY of people that DON'T. HOWEVER, it was brought into the discussion to show how an ammeter is NOT the panacea that some proclaim, as well as for those NOT that involved in electronics to realize that placement, AND impedance plays a difference in what it reads.
Complex impedance (you know, the -/+ j numbers) WILL cause ammeters to show a different reading, because they CHANGE the voltage minima and maxima. The ammeter is NOT a directional device, so if you are at a current MAXIMA for the reverse power being reflected, then you're NOT measuring Pout. Moving a ammeter, like a wattmeter, WILL cause the readings to change. This is COMPOUNDED when their is ANY reflected power (read this as reactance on the line)...... If their is no reactance at the feedpoint, no reactance on the line. Just because the METER isn't effected by reactance doesn't mean the MEASUREMENT POINT isn't effected as well. The basic accuracy of the meter isn't changed, but by measuring it at anything other than a current maxima on the forward, and current MINIMA on the reflected will you be anywhere near accurate. Or, use a dummy load.
No, all my antennas are NOT 600 ohms. I never said they where, and I also stated that if you moved the ammeter in the 600 or the 50 ohms line it would change the reading.
WTF is your 1945 comment about? People don't use OWL anymore? Tell that to The Wireman, AES, HRO, etc. that deal in open wire, ladder and window line. There is a time and place for everything...... Not to mention balun mfgs, tuner mfgs, etc.
True resistance is the R part of the complex impedance. Normalized impedance is the impedance presented, taking the reactance out of the equation. IE, 40 ohms antenna +j10 would appear nearly as a 1:1, but it is NOT 1:1, and depending on where you measure it, it will change... AND cause the voltages maxima / minima (and current) to change along the feedline.
My 4CX5000 is the driver. It hits the grid of a 3CX30,000. HOWEVER, I'm considering offing that box and going to a pair of 10's or 15s, tetrode, push pull and link coupled to 4 inch line. HOWEVER, it's your power company that decides HOW 10-8 you can be, and I've learned mine won't be powering the big box here... I CAN get 3 phase, but they only want to put up 3X10KVA xformers. WTF?
I wasn't trying to jab you at all. I was trying to show people that DIDN'T understand how things can be skewed, as well a stating you have 5 amps of RF being meaningless because who knows what the impedance is, or the voltage at the measurement point is. Just as I pointed out, and you repointed out, if you change the position of the ammeter on the feedline (OWL or coaxial ), it's going to change / skew the readings.
Have a good day!
--Toll_Free
Toll_Free
Well-Known Member
Your right! And neither will get you closer than about 10 percent, especially on a modulated waveform!
--Toll_Free
Wawasee Black Cat
I was into the CB scene from the early 70's through 1988-89? I used a Black cat JB12 made by the Wawasee company. It is a Modulator...NOT an amp. A regular 4 watt CB would drive the thing...I can't remember for sure but it either had 1,2 or 3 tubes. I actually had 2 of them. A new one as back up. They would swing over 150 if memory serves me correct. I could go anywhere I could hear with it on a Washington CB on regular AM. It was unreal. I don't know if it was just a rare set up or what but I loved the old Black cat JB12. I also had a JB150 but don't remember the numbers on swing. The JB12 did so good though. I am not familiar with the # you are asking about but it probably is very similar. IF you could take it and try it that would be a decent price if it still works good...If not, I would not give over $30-$40 for it. And then for parts unless it can be made good for a little. Just my honest opinion from experience. I am sure someone will tell you right opposite. Happens to me all the time.
I was into the CB scene from the early 70's through 1988-89? I used a Black cat JB12 made by the Wawasee company. It is a Modulator...NOT an amp. A regular 4 watt CB would drive the thing...I can't remember for sure but it either had 1,2 or 3 tubes. I actually had 2 of them. A new one as back up. They would swing over 150 if memory serves me correct. I could go anywhere I could hear with it on a Washington CB on regular AM. It was unreal. I don't know if it was just a rare set up or what but I loved the old Black cat JB12. I also had a JB150 but don't remember the numbers on swing. The JB12 did so good though. I am not familiar with the # you are asking about but it probably is very similar. IF you could take it and try it that would be a decent price if it still works good...If not, I would not give over $30-$40 for it. And then for parts unless it can be made good for a little. Just my honest opinion from experience. I am sure someone will tell you right opposite. Happens to me all the time.
3 year old thread.
Anyway, it was about a knock off black face transistor cb amp really, not the older Wawasee JB-12 from way back.
The oldest ones ran a 6AQ5 as a key tube and a 6BQ5, the later models just used the 6BQ5 and a little 2n2222a to key them.
AM only, and they are real rough at that but guys that loved AM mode just had to have one
On AVG power they really only did about 25/30 watts and about 50/60 watts peak.
They were sought after for the swing <More audio>
Set the carrier low on the radio and on audio they would go full output so it looks great on a watt meter.
Problem was they were class c in a deep way and tended to spew stuff all over.
Your friends loved it when they were talking with you, and bitching about you when you were ripping up the RX on their radio on some other channel.
73
Jeff
Anyway, it was about a knock off black face transistor cb amp really, not the older Wawasee JB-12 from way back.
The oldest ones ran a 6AQ5 as a key tube and a 6BQ5, the later models just used the 6BQ5 and a little 2n2222a to key them.
AM only, and they are real rough at that but guys that loved AM mode just had to have one
On AVG power they really only did about 25/30 watts and about 50/60 watts peak.
They were sought after for the swing <More audio>
Set the carrier low on the radio and on audio they would go full output so it looks great on a watt meter.
Problem was they were class c in a deep way and tended to spew stuff all over.
Your friends loved it when they were talking with you, and bitching about you when you were ripping up the RX on their radio on some other channel.
73
Jeff