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Author Topic: what did i do wrong?  (Read 34837 times)
NJ1K
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Posts: 3




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« Reply #75 on: November 20, 2014, 01:34:56 PM »

This may sound like a stupid question, but I need to ask.  When tuning up, as in when turning the plate or load control, the amp IS keyed up, yes?  In otherwords, the process should be, place the radio into a constant carrier mode (CW, FM, FSK) key up the radio and while keyed, turn the plate or load control as needed while watching the wattmeter to peak a reading. 

The reason I ask is because it sounded like you were keying up, then un-keying and then making an adjustment, the re-keying to see a change.  Maybe I interpreted it wrong, thus is why I ask.

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WA7PRC
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« Reply #76 on: November 20, 2014, 01:38:53 PM »

l'ld love to pick one up bryan.  Any idea where i could find such a thing at the price you mention?  As an aside, I went to RS today looking for a watt meter.  Guy tried to point me to the multimeters??.  needless to say they had none.

Not being critical, but it sounds like you need to read up on what you need and where to buy.  Get yourself a good AVG/PEP reading watt meter, (read: NO MFJ). And good heavens, stay out of Radio Shack. You can buy used meters on www.qth.com/swap all the time.

I have the FL2100B amp and using a watt meter makes tuneup fast and easy. Good luck!
My post was in regard to locating an oscilloscope so he can see if/when he's flat-topping on SSB/AM. NO meter will tell you that.

Frank: I resent the info. Let me know if you still didn't receive it.

vy 73,
Bryan WA7PRC
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WB2WIK
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Posts: 21837




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« Reply #77 on: November 20, 2014, 03:11:41 PM »

correct, changing the drive level from 45 to even 90 showed no increase in output.  swr stayed low, so low (how low) so low the needle barely moved...under 1.4-1 for sure  ii would estimate around 1.2 or 1.1-1...
I didn't try specifically reducing grid to 100 ma but i did move plate around...no difference noted.  Maybe soft tubes are a good thing, at least while I'm learning?  I didn't check swr thru out the exercise but why would it change?

It's unfortunate, but I think you're not "getting it."

This statement: "I didn't try specifically reducing grid to 100 ma but i did move plate around...no difference noted" I think indicates you don't have a feel for tuning up the amp, at all.

What Carl was trying to point out is the LOAD (not PLATE) control absolutely MUST be adjusted when you increase the drive power.  Otherwise, of course you won't get any more output, because you're not adjusting the LOAD to accommodate the increased drive.  The knob "pre-sets" or whatever the knob front panel numbers indicate don't really mean anything, I'd ignore them completely and not even bother looking at them at this point.

Every time you increase the drive power, you need to re-peak the PLATE and LOAD.  If you peak only the PLATE, that won't make it happen.  BOTH controls require peaking, and when you increase drive the LOAD control will need to be set more "clockwise," always.  The controls are interactive and you need to adjust both of them for an output power peak. 

Both controls will have an impact on GRID current.  When the PLATE tune is peaked for maximum output, the GRID current will also "peak," and you can see that happen.  But then adjusting the LOAD control will reduce the grid current when the amp is properly LOADed.  You can watch both the power output meter (wattmeter) and the GRID meter at the same time to see the effects.

The ALC control shouldn't do anything at all unless you've connected the ALC line.  If you have connected it, to get used to the tuning adjustments, I'd disconnect it for now -- and that renders the ALC control on the amplifier useless.
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AE7IS
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Posts: 96




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« Reply #78 on: November 20, 2014, 03:24:55 PM »

i would totally agree that I'm not getting it.  but to answer some concerns...
I have adjusted the grid from 150 to 25, I have adjusted the plate and load while keyed, (5 sec burst in cw mode).  I do have the alc connected...i was told in one manual that alc came into effect at 70 watts..not true?  I have adjusted the plate and load for the peak on the grid meter...wasnt that what i was supposed to do?  set plate by the book, adjust load to around 150ma on grid current and tweak plate to ensure highest output?  thats what I've been doing.  one other thing I've noticed...output changes (according to the watt meter) while on same level of drive, same frequency....meters reading the same both (many) times Ive moved the load and plate control.  just an hour ago i was trying to figure this out again...I got output to 400 watts on 20 meter and 500 watts on 17-10.  same number on plate and load ( on 20 meters) as when I was getting 300 watts?Huh  i have a lot to learn that i know
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WB2WIK
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« Reply #79 on: November 20, 2014, 03:53:17 PM »

i would totally agree that I'm not getting it.  but to answer some concerns...
I have adjusted the grid from 150 to 25,

What does that mean?  The amplifier doesn't have any grid tuning control, there's nothing to adjust.
Quote
I have adjusted the plate and load while keyed, (5 sec burst in cw mode).  I do have the alc connected...i was told in one manual that alc came into effect at 70 watts..not true?

Absolutely not true.  It's adjustable, and for the purpose of your testing and tuning, I'd recommend disconnecting it to avoid confusion.
Quote
  I have adjusted the plate and load for the peak on the grid meter...wasnt that what i was supposed to do?  set plate by the book, adjust load to around 150ma on grid current and tweak plate to ensure highest output?  thats what I've been doing. 

No!  You don't peak the grid meter with the LOAD control, ever!!  That will lead you into a spiral.  You adjust PLATE and LOAD for MAXIMUM RF OUTPUT POWER ON THE WATTMETER.  You should note that when you peak PLATE tuning for maximum output power, grid current will also peak.  However when you adjust LOAD tuning for maximum output power, grid current will not peak: It will actually reduce, as you increase loading -- which is required when you increase drive power.  Just use the wattmeter.

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VE3TMT
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Posts: 992




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« Reply #80 on: November 21, 2014, 06:28:12 AM »

As Steve is trying to point out....

Disconnect the ALC line

Connect the watt meter and dummy load to the output of amp.

If no dummy load, go to a portion of 20m where you know your SWR is flat.

Set transceiver for about 70W output on CW

Apply power and tune the PLATE and LOAD controls on amp for maximum output power. Pay only to the reading on the watt meter, ignore the amp readings at this time

Repeak the PLATE and LOAD one more time, maximum key 5 seconds at a time - they will interac with each other so quickly peak each one for maximum output power as shown on the watt meter.

What is your output power as indicated on the watt meter? What is the grid current as indicated on the amp?

Once you get the hang if it, it should take you no more than 10 seconds to tune the amp.



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KF7CG
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Posts: 1215




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« Reply #81 on: November 21, 2014, 06:33:15 AM »

At this point it might be time to power down the amp and bleed the plate supply caps for safety. The check the attachment of the plate and load knobs to the actual variable capacitors.

I have an 811H that was giving me erratic tuning reactions and just on a whim checked the connections between the knobs and the capacitor shafts. I found that two set screws were loose on the load control and one on the plate. This would allow considerable backlash and slippage when tuning. This gave "interesting" tuning results.
Reset the mechanicals to the correct place and tightened the set screws and no the amp performs as advertised.

It may just be that your amp has a screw loose.

KF7CG
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KH6AQ
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Posts: 7998




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« Reply #82 on: November 21, 2014, 06:40:39 AM »

After the amp is tuned correctly the TUNE, LOAD, and power input settings can be recorded. Then all that's needed to change bands is to set the controls to the recorded numbers, transmit and peak TUNE for maximum RF output.
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N3DT
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Posts: 1792




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« Reply #83 on: November 21, 2014, 06:51:04 AM »

Maybe this will help?

Disconnect the ALC for now.

The grid current is what it is. Only pay attention that it doesn't go higher than what the tube is rated for. More Drive level will produce produce more Ig but there's no control on the amp that you use to adjust it, but it will change as you tune the Plate and peak at max output. It's just an indicator and a good one.

The PLATE is what tunes the circuit to max output and the grid current will peak with power out. If you have an Ip meter, it will dip at max power out as the grid peaks. PLATE is the most important adjustment and always has to be set for max power out, max grid current, or minimum Plate current and all 3 happen at the same time with the PLATE knob.

The LOAD control is what you use to adjust the amp for max output coupling, within reason, but it should always be set for max output, just like the PLATE, just don't exceed any limits. It's used to properly couple the amp to your antenna/feed. If you have too much Plate current, grid current or power out you have to reduce the drive. That's why you start with less than max rated drive and work up to it until you know what you're doing, but don't start with 5W drive if it's rated for 70W, start with say 30-50W.

Pay no attention to the numbers on the PLATE and LOAD knobs or what the book says the numbers should be. You will have to come up with your own numbers. When you find the correct ones, write them down for future reference and they will all be different for each band and even each end of each band.

When you get the above parts down pat, you can start playing around with the Load control to reduce the output a few watts for max linearity, but that's not important right now.

I hope I've said it right. It would sure help if someone could show you, it's not magic.
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K4RVN
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Posts: 261




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« Reply #84 on: November 21, 2014, 07:15:48 AM »

Did not see this mentioned . Once you turn the mode from CW back to SSB after getting the amp tuned with the output you are wanting, the plate and grid readings will be a fraction of what they were in CW tune as you talk in the mic.  This is normal, but your watts out on voice peaks will be nearly the same if tuned properly. 20% of the CW readings would be OK and that's why a watt meter is important as others have pointed out. I pointed this out as you may think something is wrong when the meters  move with different readings in the SSB mode. If you don't get it to tune properly, someone experienced could be a big help. Also even if the plate and grid meters are not working properly, the watt meter will allow you to operate the amp until you get it repaired. There is a diode that blows at times on this amp that affects the meters, and the meter resistors are sometimes bad but this is rare.
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VE3TMT
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Posts: 992




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« Reply #85 on: November 21, 2014, 07:19:48 AM »

K4RVN - good point.

This is why a true PEP watt meter is a should have. It will give you an accurate indication of what the amp is putting out on SSB. Meters can not respond fast enough to human speech, therefore most meters read a fraction of what the true power is.

As for the Diamond SX-100, I'm not sure if it is a true PEP meter. I could be wrong, but a lot of so called PEP meters, do nothing but place a cap across the meter terminals when switch to PEP setting to hold the reading a little longer.
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KY5U
Member

Posts: 15




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« Reply #86 on: November 21, 2014, 07:48:01 AM »

I might add "that other forum" has a General Technical Questions area where all questions are treated with respect.  Problem is, "some hams" can't be bothered to READ so they post their question in the "opinions" forum.  Then they get their panties puffed up when someone expresses the opinion that the ham is a moron. 

This is a great forum as is the other place.  Use wisely.
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AE7IS
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Posts: 96




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« Reply #87 on: November 21, 2014, 11:28:18 AM »

i beg to differ, i was in the proper area EACH time I asked a question on that other forum, just like I did here.  I was given ridicule, put down, called stupid, "how did you pass the test" and so forth.  You, sir, can ask away on that other forum.  Are you always so judgmental , do you always make assumptions ??  This is the exact attitude I was/am talking about.  Do all you folks have a panty fetish?  And I also take offense to being called a moron (which is what you did just now)  Are you aware how much hurt you cause people by calling them names?  My daughter has  CP, she has suffered and still suffers people calling her names just because one arm works better than the other.  She has gone on to accomplish much in her life so far...teacher, mother, member of city council, her masters (have you gotten your masters?)
for those who had to listen to my rant i am sorry...people like this belong (in my opinion) on that "other" forum.
'
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AE7IS
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Posts: 96




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« Reply #88 on: November 21, 2014, 11:40:08 AM »

I really do appreciate all the HELP ( not the putdowns) but i guess some people just can't play nice.  I think I'm at a point where things are coming together.  First, i do have a watt meter which all of you said I should get.  Nice thing to have but if I may, it indicated that output is tied to grid current, that if I played by just the watt meter I would over drive the tubes. ( by looking only at the watt meter I have seen it up to 600 watts, but grid current was over 200ma).  I'm fairly happy with where I am , most of the upper bands I'm showing 400-500 watts output .   For a 811 I think that is a good place to stay.
I am quite thankful for all the help (so much that I actually subscribed).  I do think a "scope would be a good investment also, and just as needed as a watt meter to avoid flat topping, etc.
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WB2WIK
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Posts: 21837




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« Reply #89 on: November 21, 2014, 01:14:42 PM »

I really do appreciate all the HELP ( not the putdowns) but i guess some people just can't play nice.  I think I'm at a point where things are coming together.  First, i do have a watt meter which all of you said I should get.  Nice thing to have but if I may, it indicated that output is tied to grid current, that if I played by just the watt meter I would over drive the tubes. ( by looking only at the watt meter I have seen it up to 600 watts, but grid current was over 200ma).

Now you're getting there!  Good progress.

When you see what you just described ("up to 600W, but grid current was over 200 mA"), one thing you can do is turn the LOAD control (not the PLATE control) more clockwise, to increase loading.  Usually, that will reduce the grid current back into the safe range without compromising the output power.  Grid current over 200 mA likely indicates the amp is underLOADed, and that can be corrected by advancing the LOAD control some more.  That's why it's nice to have a grid current meter. Wink


 
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