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Author Topic: New Antenna Tuner, Which meter do I believe?  (Read 3149 times)
WALTERB
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Posts: 528




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« on: July 04, 2013, 12:42:29 PM »

I picked up a new Palstar ATK2K.  It seems to tune fine but I'm new to manual tuners.

I look on the dual meter and the Reflected watts is below 1:1.   The Forward power shows 5 watts (which is what I'm testing with), but the SWR meter on my TS-590s shows a much higher SWR (1:5 to 2 or higher).  this happens on 80 meters, and 40 meters, but not on 20 meters which is the resonate frequency of the antenna (80 meter sky wire loop).   

I assume its operator error?  Grin

It tunes up and all is well on 20, and 15 meters,  some on 40 but some not.

Any suggestions?

thanks
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W5DXP
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« Reply #1 on: July 04, 2013, 01:21:18 PM »

... the Reflected watts is below 1:1.

Sorry, that statement doesn't make any sense.
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73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
G3RZP
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Posts: 4328




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« Reply #2 on: July 04, 2013, 01:23:23 PM »

Run the transceiver into a known good dummy load. Check SWR

Will the Palstar run in straight through  mode to the dummy  load? If so, check the powers and SWR indications again
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WALTERB
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« Reply #3 on: July 04, 2013, 02:14:59 PM »

... the Reflected watts is below 1:1.

Sorry, that statement doesn't make any sense.

the Palstar meter shows  1  1,1, 1,2  1,3  and so on up the scale.  I can get the reflective needle to set on 1 (which is zero watts).

thanks.
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WALTERB
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Posts: 528




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« Reply #4 on: July 04, 2013, 02:15:42 PM »

Run the transceiver into a known good dummy load. Check SWR

Will the Palstar run in straight through  mode to the dummy  load? If so, check the powers and SWR indications again

yes it will.  All I need now is some oil for my dummy load.  Wink
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K7KBN
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« Reply #5 on: July 04, 2013, 04:24:55 PM »

Run the transceiver into a known good dummy load. Check SWR

Will the Palstar run in straight through  mode to the dummy  load? If so, check the powers and SWR indications again

yes it will.  All I need now is some oil for my dummy load.  Wink

If you're only using 5 watts, you shouldn't need any oil unless you plan to put a brick on the key and go see "The Lone Ranger"  Grin  .  Oil-filled paint cans are great for higher power testing, but I'd guess the actual resistors in them would be rated at least 10 watts continuous in open air.  Maybe not, but...
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73
Pat K7KBN
CWO4 USNR Ret.
WALTERB
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Posts: 528




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« Reply #6 on: July 04, 2013, 05:04:21 PM »

Run the transceiver into a known good dummy load. Check SWR

Will the Palstar run in straight through  mode to the dummy  load? If so, check the powers and SWR indications again

yes it will.  All I need now is some oil for my dummy load.  Wink

If you're only using 5 watts, you shouldn't need any oil unless you plan to put a brick on the key and go see "The Lone Ranger"  Grin  .  Oil-filled paint cans are great for higher power testing, but I'd guess the actual resistors in them would be rated at least 10 watts continuous in open air.  Maybe not, but...

from the reviews I've read,  I wouldn't last long enough watching the Long Ranger to cause a time problem.  Grin

5 watts is the minimum my rig will do. 

thanks.
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NR4C
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Posts: 306




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« Reply #7 on: July 15, 2013, 10:02:29 AM »

Go to the drug store and get a gallon of Mineral Oil for the dummy load.

What does the ATU in the TS-570 show with the Palstar in BY-PASS?

When tuning with the Palstar did you BY-PASS the built-in ATU in the radio?

Just to be sure, tune the radio ATU into directly into the dummy load and then put it in BY-PASS to use the Palstar tuner.

...bill nr4c
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WB6BYU
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Posts: 12983




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« Reply #8 on: July 15, 2013, 10:10:10 AM »

Mineral oil by the gallon may be cheaper at a farm supply store or large animal vet.

Do you have the internal tuner enabled in your rig?  If so, TURN IT OFF!  The problem
may be that the manual tuner gives a good match to the antenna, but the internal
tuner is still set to match some old antenna.  Although there may be occasions when
you might want to fine-tune using internal tuner, usually it just gets in the way when
trying to use a manual tuner.

So set the internal tuner to BYPASS and see if you still have the same symptoms.

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K8AXW
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Posts: 3599




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« Reply #9 on: July 16, 2013, 08:36:41 AM »

WALTERB: 
Quote
the Palstar meter shows  1  1,1, 1,2  1,3  and so on up the scale.  I can get the reflective needle to set on 1 (which is zero watts).
thanks

It would be best if you would study the tuner manual and get a clear understanding of the meters and what they represent. 

You're cantenna type dummy load should have a resistor rated for about 50W and it will handle 5W for a short period of time as KBN points out.  However, to make you feel better, go to a feed supply store and get a gallon of mineral oil as BYU suggest, which will get you in the game until you locate transformer oil. 

Whenever you do locate the transformer oil, drain and wash the inside of the can and resistor before replacing the oil.  While the two should mix OK, when it comes to something like this I am a purist.

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N8BOA
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Posts: 90




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« Reply #10 on: July 25, 2013, 05:57:18 AM »

On my internal SWR meter the SWR actually changes as I increase power to a certain level Try upping the power a tad and see if they start to agree. Also the SWR maybe actually be different at different points on the coax I have notice this when I measure at the base of the tower and then go inside the shack and get a slightly different reading.
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KE3WD
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Posts: 5694




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« Reply #11 on: July 25, 2013, 06:27:46 AM »

On my internal SWR meter the SWR actually changes as I increase power to a certain level Try upping the power a tad and see if they start to agree.

That is because it is a RATIO.  (And there could be a few other reasons as well for this.)

Quote
Also the SWR maybe actually be different at different points on the coax I have notice this when I measure at the base of the tower and then go inside the shack and get a slightly different reading.

And that is what happens when we move the measuring point of any Standing Wave.  Put the measuring device where the wave is a peak, you will get a much different reading than placing the same device where the wave is at a trough...

It is important to understand WHY the SWR reading became so important.  It all has to do with the advent of Solid State PAs and the fact that a high SWR will destroy power transistors unless the PA circuit contains the ever-present (in most cases) Foldback Circuitry that reads the SWR at all times and is connected such that it literally turns down the power to the amp as the SWR increases. 

Back when all the radios had tube output, SWR wasn't really all that important.  Could tune the tube output stage to the load (antenna) using the controls on the rig and even if the antenna and feedline SWR were 10 to 1 or more, really didn't matter as much as another factor, Antenna Efficiency, would.  And still does.  Its just that you have to lower the SWR to get your solid state PA to work properly. 


73
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G3RZP
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« Reply #12 on: July 25, 2013, 07:04:06 AM »

Although back in those old days of VHF TV, where TVI was a problem, we used low pass filters on the transmitter output and a high SWR could easily cause the capacitors to arc over - or on occasion, the inductors to become unsoldered. But usually the capacitors went short circuit.
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W5DXP
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« Reply #13 on: July 25, 2013, 07:44:21 AM »

Put the measuring device where the wave is a peak, you will get a much different reading than placing the same device where the wave is at a trough...

The total signal present is a superposition of the forward and reflected waves. If the SWR meter design is ideal and calibrated for the Z0 of a lossless transmission line, the SWR would be the same no matter where it is measured. Note that the higher the SWR, the lower the accuracy of the SWR reading on most SWR meters with a reading of 3:1 commonly being mid-scale between 1:1 and infinity.

The usual culprit in the non-ideal SWR meter design is the diode that rectifies RF to the DC that drives the meter(s). That voltage has to be high enough to ensure that the voltage drop across the diode is a negligible value. That's why SWR meters have power level switches on them and why a 100 watt SWR meter will not accurately measure the SWR at a one watt QRP level.

Since there are no lossless transmission lines, the SWR along the line is not a constant value. It is highest at the antenna (load) and lowest in the shack (source) because of the losses in the transmission line. For instance, 100 ft. of RG-58 driving a load of 10 ohms at 146 MHz has an SWR of 5:1 at the load and an SWR of 1.3:1 in the shack with a loss of 9dB (12% efficiency) in the coax. An SWR of 1.3:1 is good, right? Smiley
« Last Edit: July 25, 2013, 07:47:06 AM by W5DXP » Logged

73, Cecil, www.w5dxp.com
The purpose of an antenna tuner is to increase the current through the radiation resistance at the antenna to the maximum available magnitude resulting in a radiated power of I2(RRAD) from the antenna.
KE3WD
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Posts: 5694




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« Reply #14 on: July 25, 2013, 08:07:02 AM »

BALANCED LINE
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