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Modulation meter low bars on radio
- Thread starter Limeybastard
- Start date
Divide AM peak by 4 and set deadkey at or near that number. Do this for all radio's on AM and, just like 543 Dallas said this is a sure way to achieve 100% modulation.
No scopes or spectrum analyzers needed on this radio if it was NIB and unmolested. Just a good watt meter and a dummy load so no false readings from the antenna system.
Your radio is 400 watts PEP so a 100 watt deadkey and your good to go!
You probably already know this but here goes, not all meters read PEP, some will only show average output. If you have an average reading meter you probably wont see a four to one ratio..
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Problem is that is not true most of the time. Just because a radio is "new in the box" does not mean it has been properly aligned. It does mean it was "ballparked in" on the assembly line at the factory. Heck he has already complained in another post about lack of AM audio. Look at the N2 radio's from several years ago that were pulling 50+ amps right out of the box. They had a factory miscue and were puilling double what they should.
Anyways, just connected the workman hp201s swr / watt meter and turned the power dial all the way clockwise, deadkey read around 250W ( workman claim 10% accuracy) Current draw read 40A deadkey , that dead key reading is bullshit.
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9c1driver might be on to something. 40 amps with just a carrier seems very excessive. That 250 watt reading might be more accurate than you think.
I would turn the power way back when using AM. If your carrier is too high you won't have enough headroom to reach 100% modulation. It will also cause the finals to self destruct.
I would turn the power way back when using AM. If your carrier is too high you won't have enough headroom to reach 100% modulation. It will also cause the finals to self destruct.
So similar situation to the 2970N2 from 4-5 years ago?
At least Ranger RCI group are a consistent company ;-)
True, but what I'm referring to is just the deadkey /swing ratio. This is set by the user by the RF power knob. If anything I've gone in and simply found a balance with the high and low power pots and the RF knob to achieve a 4:1 ratio. I usually had good luck right out of the box having the radio near the peak rated power requiring only a deadkey setting that was in range if the RF power knob.
I have found with new radio's the AMC pot was way low that's why I mentioned this earlier. A real low AMC will affect the modulation power so I usually turn this up.
As for alignments, to me that's more involved like having the TX and RX on frequency amoung other things. Most if not all these CBs and exports are off some especially on SSB. One quick listen on 38 LSB and you can hear radio's all over the place.
So I also mean on those alignment adjustments, if you don't know what you are doing and don't have the proper equipment, leave it alone.
And, on nicer radio's like the 2900 series models, don't do the typical hack mods on it. Save that for the Galaxies or Connex's.
For the most part, the RCI2900 series are good radio's especially if you are a SSB user. A few simple adjustments were needed with mine but that's it. No need to try and squeeze a couple more watts out of it because that can cause IMD, excessive heat, and damage to the finals and makes not one bit of difference on the other end.
The service manual you were kind enough to link to , didnt show the ( or I couldnt find ) what the low dead key and high dead key should be on the 2970N4.
At least we figured why it didnt swing that much, with a dead key of 250W and swing to around 400. LOL Thats if I am seeing this correctly.
Edit. Around the 10'o clock position for the rf power dial, I get around 130W dk and 400W output little lower at around 100W dead key get about a very loud yelling auuudioooo test gets me close to 400W.
At least we figured why it didnt swing that much, with a dead key of 250W and swing to around 400. LOL Thats if I am seeing this correctly.
Edit. Around the 10'o clock position for the rf power dial, I get around 130W dk and 400W output little lower at around 100W dead key get about a very loud yelling auuudioooo test gets me close to 400W.
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AM mode only.
Before you make any adjustments, see if you can get up to 400 watts peak with a 100 watt deadkey setting first by adjusting the RF power knob. A couple of watts even up to 20 won't make much difference so don't get too hung up on it. If you are pretty close to 400 watts PEP and 100 watts deadkey, I wouldn't mess with it.
I still would turn up the AMC (VR17 AM Modulation) pot near it's peak before adjusting the power ratio because low modulation will affect the peak modulation power output some. You can tell on your peak meter if your AMC adjustment is low or high with this pot.
I see it on your picture in your earlier posts and its on the page 44 of the manual. VR19 will adjust low power deadkey setting. Have your RF power knob on a low setting before you adjust this for a starting point.
VR15 to the right of VR19 is for the high power deadkey setting but will have the largest affect on the peak power. The pots are labeled and named for easy recognition.
For peak power checking just do the AAAAAAAUDIO thing in the mic. A dummy load is best if you have one for high power, if not as long as your antenna is nicely matched you"ll be fine.
It's a combination of adjusting both pots and the RF power knob to find the closest High power setting up to the 400 watt intended limit while adjusting the low power at or near 100 watts. You will have to occasionally move the RF power knob too while adjusting the other 2 pots. Most likely the RF power knob will end up somewhere between 9 o'clock and 1 when you achieve the closest balance of 4:1. Make note of the RF power knob position when you are done and leave it there.
Don't touch any other pots. None of this will harm your radio or throw it out of whack.
As long as you get a 4:1 ratio, your modulation will be at 100% regardless of what your radio's meter says. There is a pot to adjust the modulation meter if you want but don't do it until you know your at 100% or as close as you can.
Before you make any adjustments, see if you can get up to 400 watts peak with a 100 watt deadkey setting first by adjusting the RF power knob. A couple of watts even up to 20 won't make much difference so don't get too hung up on it. If you are pretty close to 400 watts PEP and 100 watts deadkey, I wouldn't mess with it.
I still would turn up the AMC (VR17 AM Modulation) pot near it's peak before adjusting the power ratio because low modulation will affect the peak modulation power output some. You can tell on your peak meter if your AMC adjustment is low or high with this pot.
I see it on your picture in your earlier posts and its on the page 44 of the manual. VR19 will adjust low power deadkey setting. Have your RF power knob on a low setting before you adjust this for a starting point.
VR15 to the right of VR19 is for the high power deadkey setting but will have the largest affect on the peak power. The pots are labeled and named for easy recognition.
For peak power checking just do the AAAAAAAUDIO thing in the mic. A dummy load is best if you have one for high power, if not as long as your antenna is nicely matched you"ll be fine.
It's a combination of adjusting both pots and the RF power knob to find the closest High power setting up to the 400 watt intended limit while adjusting the low power at or near 100 watts. You will have to occasionally move the RF power knob too while adjusting the other 2 pots. Most likely the RF power knob will end up somewhere between 9 o'clock and 1 when you achieve the closest balance of 4:1. Make note of the RF power knob position when you are done and leave it there.
Don't touch any other pots. None of this will harm your radio or throw it out of whack.
As long as you get a 4:1 ratio, your modulation will be at 100% regardless of what your radio's meter says. There is a pot to adjust the modulation meter if you want but don't do it until you know your at 100% or as close as you can.
My post above is how I do it. I would hold off and let others chime in and see what they say.
Thanks, I noted a couple AM figures down by adjusting the user rf power dial on the outside of the radio.
Power fully counter clockwise : 8W dk, 80W Auudiooo test ;-)
Power 12 o'clock position 200W dead key, 325W audio test.
I noted the ssb figures if they matter for the above also, 220W and 520W audio test in USB mode with above dial settings.
Last night i found a post on here about directions on t
Adjusting the hi low dead key for a galaxy 98vhp, was interesting.
Member loose cannon :
http://www.worldwidedx.com/threads/dead-key-98-vhp.191508/
I need plastic screw driver and method to mark the two pots ( marker?) Before i go ahead.
Oh, and im obviously forgetting one important item, magnification lighted eye wear lol. Getting old bro!
Wow that low deadkey really cranks up there quick! The peak at 325 is close to what you want, just get the deadkey down and a bit more peak and you're there.
What Loosecannon posted on another thread is similar to how I do it. Both pots and the RF knob all inter act with each other so it's a matter of going back and forth and re-checking.
If these newer radio's still have plastic screw heads, you can use a metal screwdriver, these are simple adjustments here. The coil adjustments require plastic trimmers that go inside of a hole to adjust a screw. These you don't want to mess with because you can really throw your radio out of balance if you don't know what you are doing.
Those visor magnifiers are nice because like you my vision is going down hill and come in handy for all types of benchwork. Go get you one!
You can try marking the pots with a Sharpie pen along with a mark on the board for a reference point.