I have a palomar and the driver tube checks fine, the 2 8950 checks fine. After warming it up good swing, but if i let it idle, then when i key again it takes a long time to put out watts ???
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palomar 200
- Thread starter Number15
- Start date
Number15 said:
Tube checkers really don't have the ability to place a load on a tube just as an amplifier would so, you tube might check good but fail under a real "Load"
There is a certain "Geometry" inside your tube that effects how it tunes and how it puts out watts. As your tube heats up, the values change because the distances between the elements change which effects your tuning.
When you tune the tube cold it will work one way, when you tune it while it is hot, it will work another way.
Substitute a driver tube and see if the symptoms change.
There is another part that if it is changing in value in relationship to heat could cause you a problem; the DC blocking cap (500 pf at couple of thousand volts) if it is failing then it is possible that it is affecting your tuning.
Hey, what's happening with your SWR when you see these changes because the amp is heating up (putting out more watts), how's the coax and antenna connections and conditions?
palomar
coax is good and swr check good, watts is about 220 .just slow to key every time i go to talk. and i did change the tubes both drive and final and showed same readings??
coax is good and swr check good, watts is about 220 .just slow to key every time i go to talk. and i did change the tubes both drive and final and showed same readings??
Re: palomar
It should be 4 watts.
Number 15, only after the cathode reaches an optimum temperature will the tube have maximum emissions and output.
Just my opinion but, whosoever came up with this idea of keying your amp with 1 and 1/2 watts (especially a tube amp) were disingenuously mistaken. That's not enough watts to make the electrons flow.
.
Number15 said:
It should be 4 watts.
Number 15, only after the cathode reaches an optimum temperature will the tube have maximum emissions and output.
Just my opinion but, whosoever came up with this idea of keying your amp with 1 and 1/2 watts (especially a tube amp) were disingenuously mistaken. That's not enough watts to make the electrons flow.
.
200
Kool work better now at 2 watts. But i wil bring it up to four. thanks. maybe i should put a variable in my radio, so i dont have to open it.
Kool work better now at 2 watts. But i wil bring it up to four. thanks. maybe i should put a variable in my radio, so i dont have to open it.
Re: 200
A little bit more about the amp; all the elements inside the tubes (control grid, screen and supressor grids) are grounded. This make these tubes act like triodes (mini-3-500Z) so, it is normal that they have to heat up internally before you will see higher output. Also, when they cool off the watts drop.
If there was someone in your area who knows tubes, they could put some negative bias on the control grids of those tubes for one thing and, some plus volts on the screens of those tubes, that would increase the output and give you some dynamics and a more desirable duty-cycle.
Sure, put a variable on your radio, it will give you something to do with your hands while you are alone in the radio room and boredom sets in....
Mel
Number15 said:
A little bit more about the amp; all the elements inside the tubes (control grid, screen and supressor grids) are grounded. This make these tubes act like triodes (mini-3-500Z) so, it is normal that they have to heat up internally before you will see higher output. Also, when they cool off the watts drop.
If there was someone in your area who knows tubes, they could put some negative bias on the control grids of those tubes for one thing and, some plus volts on the screens of those tubes, that would increase the output and give you some dynamics and a more desirable duty-cycle.
Sure, put a variable on your radio, it will give you something to do with your hands while you are alone in the radio room and boredom sets in....
Mel