Cecil:
Well, these "hyperbrite" leds I am using mask the effect a lot--but since
the FWD and REW run though the same current limiter, if the REV current goes
up though its' led--it starves the FWD from some of its' current--so as you
see one led get brighter--you see the other grow dimmer (kewl to show to cb
buddies grin)
But, seriously, even more desirable, is you don't need to pay any attention
to the direction in which you insert it into the line....
I don't have a RF vtvm Cecil, and too lazy to build a probe... but, under
test conditions something made the FET fail--I suspect too great of
voltage--I have used that fet/led arrangement for "test lamps" on 5~32v with
never a failure (although my datasheet on the mpf-102 says 25v max), I
suspect the voltage went somewhere beyond 32v when it fail (failed in
shorted condition too, both LEDS were "BRIGHT!!!!")...
But, thank you for your time in commenting--I will NOT ignore your input and
keep it in mind--but still, as Roy pointed out--doesn't pay to push
component capabilities to their max and beyond...
in real use at least...
Warmest regards,
John
--
When Viagra fails to work--you are DOOMED!!!
"Cecil Moore" wrote in message
...
| John Smith wrote:
| It was pointed out, that this was over-stressing components capabilites
(Roy
| even made comment)--the FET will just not take the demands put on it at
10
| watts (I ran the ten watts through a resistive splitter and sent ~5
watts
| too it--with a new FET, it lasted long enough for proof of concept
tests...
| then FET blew again)
|
| For a matched Z0=50 ohm system, five watts of forward power
| is 15.8 volts. When calibrated, the voltage from the toroid
| has to equal that voltage. That means, for the forward power
| indication, 31.6 volts must be tolerated for five watts.
|
| For reflected power, the current will be driven by the difference
| of the two voltages. When matched at five watts, that difference
| will be 15.8v - 15.8v and the LED will be dark. This might be a
| hint to eliminate the forward power indication altogether and
| go with only a reflected power indication. After all, the reflected
| power indication is the most useful and when zero, the system is
| matched.
| --
| 73, Cecil
http://www.qsl.net/w5dxp
|
|
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