Questions for 98vhp owners

[LeapFrog]

If it will do just that on the peak side, why not on the average side? Why is only the peak numbers going wide open and not the average reading?

Ok, so instead of a 'Peak Expansion' mod, do the NPC-RC, oh the 'scope is down.
This'll give you positive carrier shift from low dead key, disable the AMC, "volt the final"....

Edit: Yup Robb called it, what kind of PSU are you using? Maybe it's starving for current.
Or maybe it's out of alignment, a little too much playing with the adjustments from the previous tech?

 

[Robb]

Back swing suggests a lack of feed power to the radio; that would be my first guess. Since the radio is going to draw a lot of current; then check your supply an feed wire connections.

 

[TheRealPorkchop]

Ok, so instead of a 'Peak Expansion' mod, do the NPC-RC, oh snap 'scope is down.
This'll give you positive carrier shift from low dead key, disable the AMC....

Edit: Yup Robb nailed it also, what kind of PSU are you using? Maybe it's starving for current.

If I reconnect the diode, the swing goes forward. I'm using a 125 amp Cosel power supply set at 14.5 volts, according to the voltmeter connected to it, there is no drop at all in voltage. I can not tell you what the amp pull is though. But if it were a loss of feed power, it should do it with that diode hooked up, not just unhooked, wouldn't you think? I'm pretty sure this radio doesn't pull 125+ amps

Back swing suggests a lack of feed power to the radio; that would be my first guess. Since the radio is going to draw a lot of current; then check your supply an fees wire connections.

I guess I wasted a good quote here, haha, I basically responded to this above the quote...my bad.

 

[LeapFrog]

If I reconnect the diode, the swing goes forward. I'm using a 125 amp Cosel power supply set at 14.5 volts, according to the voltmeter connected to it, there is no drop at all in voltage. I can not tell you what the amp pull is though. But if it were a loss of feed power, it should do it with that diode hooked up, not just unhooked, wouldn't you think? I'm pretty sure this radio doesn't pull 125+ amps




I guess I wasted a good quote here, haha, I basically responded to this above the quote...my bad.

It's the internal adjustments then, combined with the modification, that is all it can be, unless you've had an undetectable part failure somewhere. Sorry to sound so basic but, what else could it be.

Chop, you need the 'scope to really see what she is doing, at this point the watt meter ain't enough my man. (Rebuild the analog one's power section!)

 

[TheRealPorkchop]

Chop, you need the 'scope to really see what she is doing, at this point the watt meter ain't enough my man. (Rebuild the analog one's power section!)

I am scared of that 100 volts DC... I'm accident prone... and a crap magnet. If you've been reading post by me on other radio forums, you should know that, haha.

 

[LeapFrog]

I am scared of that 100 volts DC... I'm accident prone... and a crap magnet. If you've been reading post by me on other radio forums, you should know that, haha.

Woops, lol!

The one that stands out in my mind is the post about a 2SC2290 final mod for a galaxy radio!

And that is very true, I was scarred sh*tLess changing a cap in my CRT 'scope, "extra resistor" for discharging lol that was a riot.

 

[TheRealPorkchop]

Yes, I posted that information a long time ago, I still have it somewhere. It's a rather crude method I think and I thought people were getting ripped off, so I bought the plans and then posted on the that shiny metal forum, I think.

 

[LeapFrog]

Yes, I posted that information a long time ago, I still have it somewhere. It's a rather crude method I think and I thought people were getting ripped off, so I bought the plans and then posted on the that shiny metal forum, I think.

10-4 on the shiny metal forum, that's the place I remember your handle from!
Likewise, I too cannot stand it when people are being ripped-off!


Thank you for paying for the info and then sharing it, I think people in the CB scene who try to hide "Tech Secrets" and price-gauge for crap like PDF files on a CD (when they didn't even aggregate the files on their own time) are the worst.

I wish you luck on getting the radio to perform how you need it to.

 

[TheRealPorkchop]

10-4 on the shiny metal forum, that's the place!
Likewise, I too cannot stand it when people are being ripped-off!


Thank you for paying for the info and then sharing it, I think people in the CB scene who try to hide "Tech Secrets" and price-gauge for crap like PDF files on a CD (when they didn't even aggregate the files on their own time) are the worst.

Oh you're welcome, it's no problem. I'll go back to fiddling with this raggedy radio and see if I can figure out what's going on... I'll be back.

 

[LeapFrog]

Oh you're welcome, it's no problem. I'll go back to fiddling with this raggedy radio and see if I can figure out what's going on... I'll be back.

10-4, check if they don't have a low and a high power pot, if they use two to control the carrier (because of the variable) your "average swing" will be found after tweaking those, I hope so anyway. It's a balance act, and it peaks better one way than the other, you may have 3 areas to adjust, the knob, and the one or two internal AM carrier pots.

Sorry, I don't own a 98VHP.

 

[TheRealPorkchop]

Yes, there's two variables inside the radio to set the low/high limits plus the variable on the front of the radio.

When I got this it had a 390 ohm resistor and a 914 diode. I read somewhere else on this forum that the NPC had to be done with a 4001 and a 100 ohm resistor, so I tried that but I didn't remove any limiter nor did I run any red power wire. I also started tinkering with changing values on the resistor and started using a 914 diode cause I have way many more of those than anything else.

With a 15 ohm resistor, I wanted to use a 51 but don't have any, and a 914 diode, I am now seeing about 90 watts average from the 10 watt carrier. From the 65 watt carrier, I'm seeing about 125 watts, the peak remains the same regardless. I've been trying various resistors and 15 ohms seems to emulate what I've seen from other radios. Now, are those true power readings or just bogus ghost watts that are actually harmonics? I don't know because my scope is messed up and I can't see the modulated carrier and I don't own a spectrum analyzer, yet. I've thought of buying one of the USB ones but I'm not so sure those things are really worth the effort.

Now, the question in my mind is if I can get that 125 from 65 watts of carrier, why can't I get it from a lower carrier? I'll assume that's due to a modulation limit maybe? Or maybe it's just distortion and harmonics and I can't achieve that from a lower carrier? I honestly don't know, I'm just talking out loud here and guessing. Without the scope I know it's impossible to set the radio the correct way, I've just been wanting to see why this radio didn't do what others had done. Now the question is how it sounds and are those real numbers or just BS, I'll take my chances with BS. I started to pull the limiter but I don't really like to do that but I may just to see what happens.

So again, does anyone here have a 98VHP and if so, what has been done to yours and what numbers are you seeing?

 

[Robb]

NPC/RC of course stands for 'negative peak compression/reduced carrier'. So your diode/resistor part supplied the negative peak compression part of the mod; but the reduced carrier is done as an adjustment that you do. So you will need to adjust the carrier on low power down to 5w and on high is should be set to 30w. Of course, that is true for 200% modulation increase, and since you don't have a working scope; then you cannot test the amount of modulation percentage change. Try those values and see if it runs cool and doesn't exceed 250w/PEP in high.

 

[TheRealPorkchop]

NPC/RC of course stands for 'negative peak compression/reduced carrier'. So your diode/resistor part supplied the negative peak compression part of the mod; but the reduced carrier is done as an adjustment that you do. So you will need to adjust the carrier on low power down to 5w and on high is should be set to 30w. Of course, that is true for 200% modulation increase, and since you don't have a working scope; then you cannot test the amount of modulation percentage change. Try those values and see if it runs cool and doesn't exceed 250w/PEP in high.

Well being in a hurry and not paying attention, you're absolutely correct and I missed the second part of that, reducing the carrier. Thank you. I tried the numbers you suggested and I believe it's a little cooler but it's still a damn hot radio if you run your mouth for extended periods. With the 30w carrier, it modulates to 100w on the average side and 250 on the peak, so I assume that's in the ballpark of where it needs to be. I'll be fixing my scope but not today...

I'm not crazy about doing this "mod" but some people like to see big numbers and that impresses them. If I go to sell it and it doesn't impress, it'll just sit on the shelf out here with me and take up space. I do like the voice changer, it's fun to play with through the talkback on the dummy load. But I'll have to say that I like my S9 much better... Pat would be proud.

 

[Robb]

These kinds of mods may work OK in AM mode; but if you want to use SSB at any point - it turns it into a giant turdbox. I've undone several of these mods because of that fact.
Just a heads up - is all . . .

 

[TheRealPorkchop]

Well, yea I know. If I wanted to talk sideband though for anything other than CB, I'd use my Yaesu.

There is an SSB issue with this radio that I've stumbled across tonight while hunting this issue out. You can't adjust the transmit offset for USB or LSB. The AM offset is dead on but SSB is off and turning the adjuster pots makes no changes. I don't know if I'll bother with it past the time I've invested so far. On one hand, I got a good deal, on the other...giant turd comes to mind.