I almost brought up the laws of physics when you were talking about a 20 watt carrier and clean signals from those little finals. Glad you snapped out of it.
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FINE TUNE CB SHOP FOR REAL?
- Thread starter Sonar
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I almost brought up the laws of physics when you were talking about a 20 watt carrier and clean signals from those little finals. Glad you snapped out of it.
I was told the driver is a bipolar transistor driving 3 of those mosfets.
It doesn't really sound too far-fetched.
He did say it would blow up if I used it for very long at that power level.
Lo and behold it did blow up a couple days later as he was using it so he had to replace the finals.
That is my radio right there. Maybe somebody could blow that picture up and see what that meter is reading.
I was told the driver is a bipolar transistor driving 3 of those mosfets.
It doesn't really sound too far-fetched.
He did say it would blow up if I used it for very long at that power level.
Lo and behold it did blow up a couple days later as he was using it so he had to replace the finals.
That is my radio right there. Maybe somebody could blow that picture up and see what that meter is reading.
I can't make out the slug chop. It does appear to be in pep mode but I'm not sure why a pep kit is necessary for a man with a scope. I use a standard bird 43 and adjust the modulation with a scope. If I can't hit 100% modulation without waveform distortion I reduce the carrier and try again. A pep meter really doesn't serve a purpose here unless you don't have a scope.
If it were a 10 watt slug its about 7 pep
a 25 watt slug would be around 17.5 pep
a 50 watt slug would be 35 pep....I can't see it being that clean on the spec analyzer at 35 watts with those baby finals. Also, unless I'm mistaken a single tone test is not sufficient for an accurate IMD measurement. The waveform tells me it's only a single tone. Someone please correct me if I'm wrong.
A 100 watt slug would be 75 pep....not going to be that clean with those finals and you know it ain't a 250 watt slug.
There are no other size bird or coxial dynamic slugs that I know of. Is it safe to say the super clean videos are shot with piss weak power as I suspected?
Based on what he told me about output power I guess he's saying that there's a 100-watt slug in that meter.
I think that picture might have been taken after he blew it up the first time and replaced the finals with the irf520.
I'm not exactly sure when the picture was taken. It was either before it blew up or after he rebuilt it.
I think that picture might have been taken after he blew it up the first time and replaced the finals with the irf520.
I'm not exactly sure when the picture was taken. It was either before it blew up or after he rebuilt it.
https://www.w8ji.com/alc_exciter_power_overshoot.htm
Actually a good pep meter is more accurate than a scope.
That's a pretty interesting article but there's lots of things that you can see on a scope that would never be measured accurately with a meter unless of course you know the purity of the signal that you are measuring.
According to the bird 43 manual the measurement must be taken in a precise scientific manner which lots of people like to argue about.
And how are you going to quantify a reading on a needle.. unless it's digital?
The linked article is also pretty old by today's standards. As such is requires the usual grain of salt. things have changed since 2011 and before.. like some of his references to observations made in 1990 - 25+ years ago?
Not saying it's wrong... just that it probably needs to be updated/verified.
We're talking radio alignments and modulating the transmitter with a tone generator. Overshoots and the meters ability to catch them do not apply in this instance as it would when a voice is used. Mark is showing off what his radios do under lab conditions not day to day use. That's what I'm focused on.
In the first paragraph w8ji said he had issues with the coaxial dynamics and bird meters (What mark is using) and recommended the ameritron meters....im sure he is partial the ameritron because he likely helped with the design.
I have used those ameritron meters btw. They seemed to be accurate for measuring pep when compared to a scope using a steady tone but carrier level measurements were off when compared to a bird 43. The first awm 35 I had worked great, unfortunately it was dropped and broken. The second was sketchy tuning up at legal limit. Erratic meter movement, backlight flickered and actually stopped working at one point.
Looking inside there were some changes to the circuit compared to the older unit. I recommend one to a friend before buying my second. He says he had similar issues and doesn't use it. For these reasons I will not buy another or recommend one to a serious operator with power. A watt meter that is susceptible to rfi is no good for me.
For keeping an eye on overshoot I like my rea modulation monitor. You're right about the scope being hard to watch but no pep meter can monitor modulation percentage in the negative direction. The rea can, is fast and has peak hold which is also adjustable iirc.
I would take it a step further and say that only when the Purity of the signal is known and the current and voltage are equal can an accurate measurement be taken. If current and voltage are not equal, reactance varies with frequency Due to capacitance and inductance.
Capacitance and inductance cause phase shift which changes the accuracy of a measurement.
Capacitance and inductance cause phase shift which changes the accuracy of a measurement.
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RPC i agree 1/2 wavelengths will reduplicate.
LS i agree on being updated.
543 I guess i have been lucky mine works fine.
The rea you mention sounds cool. I will check it out.
Good info.
LS i agree on being updated.
543 I guess i have been lucky mine works fine.
The rea you mention sounds cool. I will check it out.
Good info.
Throw a 2kw carrier into it tuning up and see what happen. That's close to legal limit but that was on 11 meters so it doesn't count.
Throw a 2kw carrier into it tuning up and see what happen. That's close to legal limit but that was on 11 meters so it doesn't count.
Lol..... i can imagine . Guess that's why they call it Mighty Fine Junk.
also it was probably meant for ssb.
tI would take it a step further and say that only when the Purity of the signal is known and the current and voltage are equal can an accurate measurement be taken.
Also when current and voltage are in Phase is when maximum power is radiated.
Maximum Smoke is what the ole timers call it.
I did not know that was even possiblet
Also when current and voltage are in Phase is when maximum power is radiated.
Maximum Smoke is what the ole timers call it.
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