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So pushing that 100 watt radio to 140 watts out, delaying ALC and by that also the protection circuit for bad swr?
Guaranteed you bloww your output transistors when you get bad or infinite swr because the ALC won't fold back power fast enough and transistors are the fastest fuses on the planet....
Same as the other mod, causing IMD, risking your P.A. transistors and extra heat in the radio.
Guaranteed you bloww your output transistors when you get bad or infinite swr because the ALC won't fold back power fast enough and transistors are the fastest fuses on the planet....
Same as the other mod, causing IMD, risking your P.A. transistors and extra heat in the radio.
B
big_sho9
Guest
But wouldn't that make you feel like you've been cheated if you bought an advertised 100 watt radio, and it only put out 70 watts?
99% of the people that complain their radio does not put out the rated 100 watts have metering errors. Usually expecting a non-powered meter that CLAIMS to read pep to actually read pep. Meters that have an AVG/PEP switch but do not require power to work (other than light a panel lamp) do NOT read pep regardless what the manufacturer says. That is a LARGE percentage of the problem.
Those type of meters simply switch a capacitor into the metering circuit that holds the meter a bit higher but it is still too slow to respond to TRUE pep levels. There actually has to be an amplifier circuit to measure true pep values and that of course requires a power source to operate.
Nope, not at all. I am not buying a radio for its power output, I buy the radio based on how it would work out for me.
One thing to keep in mind, as a ham, at least for me, most are not all that interested in power output. Most hams are more interested in antennas and their performance. As a ham I know I can run 2k legally but I have zero interest in doing so. I have worked stations all over the world on 100w or less (mostly less) on a bunch of wires hanging from a tree. I am perfectly happy with that.
To answer your power question, I run a Yaesu FT-101ZDmkII, It's rated at 100w out. On most bands, I get near 100w (more mostly) but on 10 meteres I get 75. I am perfectly happy with that and to go along with CK's posts I do use a powered true PEP reading meter.
It's not all about the radio...
To answer your power question, I run a Yaesu FT-101ZDmkII, It's rated at 100w out. On most bands, I get near 100w (more mostly) but on 10 meteres I get 75. I am perfectly happy with that and to go along with CK's posts I do use a powered true PEP reading meter.
It's not all about the radio...
I hate to say it but this is a bad modification. Icom is notorious for having the most aggressive ALC of any major brand. The problem has nothing to do with reaction time and everything to do with the level at which ALC voltage begins to rise. We should be adjusting resistor values to reduce the level of ALC rather than retarding its action with additional capacitance.
If the ALC cannot respond to a fast peak, it will also be inhibited from reducing power in a fault condition such as an intermittent antenna connection. Also consider what happens when this added cap is hit with enough word peaks, or a more consistent tone and actually reaches 2/3 or more of the charge voltage that the ALC line is applying to it... It will revert back to the lower power level and hold it there until the cap discharges.
Bypassing the splatter filter to please the watt meter is a definite no no too. If it were me, I'd go right after the gain controlling resistor in the negative feedback loop of the ALC op amp. From what I can see in the blurry video numbers, it looks like R1537 and is a 330k resistor. Try a 500k or 1 meg, mini potentiometer in parallel with the existing resistor, on wires just long enough to adjust with the board installed.
Find the "sweet spot" (100 watts real PEP) and remove the wires for a direct install or use a fixed resistor if a standard value is close to the setting of the pot. From looking at the schematic it appears to me that reducing the value of this resistor should increase the available output, before ALC begins to restrict power. More important, is that the ALC is also used to protect the finals and output filter capacitors, in a high VSWR condition and this approach will not delay the ALC response time.
If the ALC cannot respond to a fast peak, it will also be inhibited from reducing power in a fault condition such as an intermittent antenna connection. Also consider what happens when this added cap is hit with enough word peaks, or a more consistent tone and actually reaches 2/3 or more of the charge voltage that the ALC line is applying to it... It will revert back to the lower power level and hold it there until the cap discharges.
Bypassing the splatter filter to please the watt meter is a definite no no too. If it were me, I'd go right after the gain controlling resistor in the negative feedback loop of the ALC op amp. From what I can see in the blurry video numbers, it looks like R1537 and is a 330k resistor. Try a 500k or 1 meg, mini potentiometer in parallel with the existing resistor, on wires just long enough to adjust with the board installed.
Find the "sweet spot" (100 watts real PEP) and remove the wires for a direct install or use a fixed resistor if a standard value is close to the setting of the pot. From looking at the schematic it appears to me that reducing the value of this resistor should increase the available output, before ALC begins to restrict power. More important, is that the ALC is also used to protect the finals and output filter capacitors, in a high VSWR condition and this approach will not delay the ALC response time.
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B
big_sho9
Guest
LOL its 2.5 for me,,
For all you guys that are flaming down the mod post,,, Are you speaking in theory, or have you actually tried it and put it on an anal liser or silly scope? because i have owned, and do own a few like this.
B
big_sho9
Guest
heres an amp mod: ameritron likes to use this thread size coax to go between the input to the band selector. replace that with bigger coax and you can then drive the heck out of it!! it seemed like my al15 wouldonly tke 60 watts of drive until we changed that coax.
Well, if you own a scope and analiser, what is holding you to try out that modification and come back to us with the results?
I repaired enough golden screwdriver mods in ham radios and Cb radios to know the only result of these mods are more expensive work on the workbench.
Look into the data of the P.A. transistors about IMD at specified voltages and output power as well 1 dB compression point effects driving the hell out of them.
Then look at the heat dissipation the manufacturer uses for that 100 watt P.A. and not 140 or 150 watts out .
Then come back and tell us it is still worth it to get 2 dB gain.
Or if it is better to use a decent amp to make 1000 watts and really make a difference without splatter and risking your expensive P.A. transistors.
As in my first post the delay in ALC action will NOT protect the P.A. transistors in case of bad swr or infinite swr, the transistors will blow.
Hacking modern radio's is now done in the engineers software menu.
No need to hack it as if it is a cb radio.
IN my FT991A i replaced the fan with one of higher cf/m and more silent with longer mtbf, maglev type.
Why? becaus i like to keep my radio's cool and last longer.
Not to hack them and drive them over the design parametes.
If i need more power my rebuild Heathkit SB 1000 gives me all power i need.
But then with my antenna's i run 99.9% of the time just 100 watts, better invest in good antenna systems ( antenna's coax etc).
That works both ways receive and transmit, or you can play the crocodile big mouth small ears.....
I repaired enough golden screwdriver mods in ham radios and Cb radios to know the only result of these mods are more expensive work on the workbench.
Look into the data of the P.A. transistors about IMD at specified voltages and output power as well 1 dB compression point effects driving the hell out of them.
Then look at the heat dissipation the manufacturer uses for that 100 watt P.A. and not 140 or 150 watts out .
Then come back and tell us it is still worth it to get 2 dB gain.
Or if it is better to use a decent amp to make 1000 watts and really make a difference without splatter and risking your expensive P.A. transistors.
As in my first post the delay in ALC action will NOT protect the P.A. transistors in case of bad swr or infinite swr, the transistors will blow.
Hacking modern radio's is now done in the engineers software menu.
No need to hack it as if it is a cb radio.
IN my FT991A i replaced the fan with one of higher cf/m and more silent with longer mtbf, maglev type.
Why? becaus i like to keep my radio's cool and last longer.
Not to hack them and drive them over the design parametes.
If i need more power my rebuild Heathkit SB 1000 gives me all power i need.
But then with my antenna's i run 99.9% of the time just 100 watts, better invest in good antenna systems ( antenna's coax etc).
That works both ways receive and transmit, or you can play the crocodile big mouth small ears.....
I serviced Icom, Yaesu and Kenwoods for a factory authorized distributor for many years. I'm well versed in normalizing the aggressive ALC in Icom HF rigs. Engineers invest a lot of time designing protection circuits that are fast enough to protect transistors. You want to correct the level of ALC and never add parts to delay its ability to function. You'll notice even with all of that test equipment available right in front of him, you only get to see the watt meter.LOL its 2.5 for me,,
The scope would clearly reveal what is actually taking place and I was able to see it on his meter at one point where his voice was louder than just a quick peak. The loud audio that followed right after, never reached the power that charged the cap just prior, because it reached the charge voltage and put the ALC right back where it was originally, after that cap charged. The mod has really done nothing but allow the FIRST part of any peak to pass until the ALC has time to clamp it right back to where it was.
Hit it with a solid tone and watch the high peak appear just long enough to please the watt meter and disappear right after. Listening to that in the distance will make every breath pop and brief peak sound louder than all of the average speech. It's almost like using a speech compressor in reverse. Bypassing the splatter filter is not going to make any friends on the HF bands, for anyone trying to use a frequency close to you either...
Not for nothing but adding the cap with long uninsulated leads right over the top of other parts, is a disaster waiting to happen for any mobile rig. At least glue the part down to the board. How many bumpy rides do you think it will take to vibrate the cap enough to snap the leads off at the solder connections? Some of the most impossible failures to troubleshoot are those caused by conductive material that moved across the powered up PC board. That's because they follow no rhyme or reason for logical part failure and can cause multiple failures all at once.
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I've owned my 101ZD since 1984 and it still works great today. That was built back in the day when you could throw a radio out the window and have it land on the driveway 10 feet below, and still worked with a big dent in the corner. I know because I bought one from a friend back in high school, who's father threw it out the window due to repeated TVI.