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Open wire feeder balanced LED current indicator by PA0LL




 
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Author Topic: Open wire feeder balanced LED current indicator by PA0LL  (Read 11214 times)
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aa5wg
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« on: June 12, 2011, 04:40:14 PM »

What do you think about this current indicator(s) for your ladder line?  Click on link:      

http://zonnepanelen.a-bc.org/pa0ll-antenna-current-indicator-mpg/

Would this device would best at a high voltage or high current loop at the connection point of the antenna tuner and ladder line?

73, Chuck
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w5gw
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« Reply #1 on: June 13, 2011, 08:30:52 AM »

In late 50's I used to have two small neon bulbs with short pieces of wire (maybe 3" on each leg) that were shunting the feedline in my shack.  They were great output tuning indicators.  This looks like a fancy equivalent of that...
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W3GMS
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« Reply #2 on: June 13, 2011, 08:47:36 AM »

Chuck,

The link that I saw did not provide much information.  It appears that the product uses toroidal current transformers.  Primary current becomes a secondary voltage across a termination resistor.  That voltage then is read and displayed as a current.  Nothing at all wrong with that basic concept.  I would prefer to just have an analog meter rather than the LED's.  I am not sure of what steps or resolution he is using to go from one LED being on and the next higher LED and when it becomes active. 

This unit is designed to measure feed line current so a high voltage / low current point on the line will produce a much lower reading that when its looking at the high current portion of the open wire line. 

I would consider it as more of a light show than a serious instrument in my opinion!  Take the concept and build something yourself...

Joe, W3GMS   
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aa5wg
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« Reply #3 on: June 13, 2011, 10:15:50 AM »

W5GW and Joe:
Thank you for your input.  I like analog meters the best.  However, I am going to try 250ma, 120 volt neon bulbs and 6 volt 6 watt incandescent bulbs.
Maybe these bulbs will be to big to work barefoot?  What do you think?
Chuck
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W2PFY
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« Reply #4 on: June 13, 2011, 11:38:18 AM »

If you click on it and take it out to the YouTube site, you will see an antenna tuner in the background. There is another video of the antenna tuner that has belt drive roller inductors. Looks like it may be an auto tune type. Not much information on it though? It also looks like it's from the same builder but I think it's in the German language.
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« Reply #5 on: June 13, 2011, 12:07:31 PM »

Hi Terry,

I looked for more information on the flasher on his website also. I saw the tuner as well but no information on the flasher. I did see (I think) that it will handle 10 amps but only 100 watts? That seems odd to me but I can't put my finger on it.

PA0LL is in the Netherlands and Dutch is a Germanic language so it sounds and is spelled  similar.

Mike
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k4kyv
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Don
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« Reply #6 on: June 13, 2011, 12:16:45 PM »

Looks like you have to cut the OWL and insert the instrument in the gap.  Now, what happens at the first nearby lightning discharcge?
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Don, K4KYV                                       AMI#5
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w5gw
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« Reply #7 on: June 14, 2011, 07:26:40 AM »

W5GW and Joe:
Thank you for your input.  I like analog meters the best.  However, I am going to try 250ma, 120 volt neon bulbs and 6 volt 6 watt incandescent bulbs.
Maybe these bulbs will be to big to work barefoot?  What do you think?
Chuck

Well I used small neon bulbs that were in panel displays at the time.  I don't know their specifications.  One didn't cut the open wire feedline (back then it was bare wire with ceramic insulators) but just shunted each leg with the bulb.  The bulbs you indicate are probably too large to fire.  Also as someone else indicated, current changes along the feedline, so as I recall I had experimented with placement and shunt length to get optimal readings. Also, placement of the current nodes and minima will change with different bands.

W5GW
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W3GMS
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« Reply #8 on: June 14, 2011, 09:01:58 AM »

Hi Gary,

Well you will have to do some trial runs on measuring your feed-line current with the bulb types you mentioned.  The smallest shunt wire will be when you are at a high current portion of the feed-line.  I would simply go to the back of the tuner where the open wire line connects and replace that with a short piece of non insulated wire.  Then take whatever bulb you want to try and start with 2 clip leads connected to the bulb.  Start with the clip leads connected very close together and then gradually increase the distance which will increase the voltage across the bulb.  Once you know the span between the tap points simply measure the distance and do the same at the exact location on the other side of the feeders.  The problems with bulbs is the light appears to be very non linear to the eye.  So judging minor difference in light output while looking for balance may be tuff depending on how much current you have flowing through the bulb.  I sometimes use bulbs in series with the HV on simple 1 tube transmitters as a tuning indicator and sometimes looking for a resonant dip gets pretty tuff depending on where the light is biased on the light curve! 

Joe, W3GMS     
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aa5wg
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« Reply #9 on: June 14, 2011, 11:10:42 AM »

Hi Joe and all:
Thank you for you thoughts regarding light bulbs and current on the line.
I thought I would try placing a small coil in series with one bulb and moving this coil close to the tank coil for pick up.  Hopefully the light will get bright during this test.
Chuck
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W3GMS
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« Reply #10 on: June 14, 2011, 04:03:57 PM »

Chuck,
If your running enough soup, the lamp will light! 

Have fun!

Joe, W3GMS

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aa5wg
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« Reply #11 on: June 14, 2011, 08:45:24 PM »

Joe:
Thank you.
Chuck
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w5gw
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« Reply #12 on: June 16, 2011, 09:15:01 PM »

Chuck, your idea is good - if you add a variable capacitor you can tune this to resonance.  I have a set of wave meters that use this principle.

Gary
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W3GMS
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« Reply #13 on: June 16, 2011, 10:01:49 PM »

Gary,

Might that be a Bud Wave Meter?  I have one and it works well.  Then again, they are not very complicated.  Mine was either late 40's or early 50's. 

Joe, W3GMS   
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k4kyv
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Don
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« Reply #14 on: June 16, 2011, 10:16:18 PM »

Miniature Xmas tree incandescent lamps operate at only a couple of volts and minuscule current.  You should be able to wire them to two points just a short distance apart on the OWL.  I would think they would be much more sensitive than regular pilot lamps. I'd try it, and if they work, buy a bunch of the lamps if you don't already have some old strings of lamps. Most likely, in a couple of years you won't be able to find incandescent xmas tree lamps any more.
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Don, K4KYV                                       AMI#5
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aa5wg
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« Reply #15 on: June 17, 2011, 03:43:02 PM »

Joe, Gary, Don and all:

(Miniture incadesent Christmas tree lights and Wave Meter)

If I add a variable capacitor in series with a pickup coil and light then I could adjust, "tune", my light for brighter or dimmer settings while tuning the main link antenna coupler circuit to resonance.  
(1) Would this work?

This pickup coil would be near the tank coil of the link antenna coupler.  
(2) Do you think this pickup coil would detune the link antenna coupler?

I was hoping this fixed "tuning" light approach would help eliminate the need to find and change tapping points along the ladder line for the incadesent light bulb (current tune).

(3) If needed, could I use a neon bulb in series with the pickup coil and variable capacitor to tune the light to resonance (voltage tune)?

When I say tune the light I mean adjusting its own varialbe capacitor for brightest light without burning it out.  If during the tuning of the main link coupler circuit the light is getting to bright I could detune the light with its own variable capacitor to lower its brillance and not burn in out.   Then, I could continure with the tuning of the main link antenna coupler.

The tuning of the link antenna coupler is sepparte from the adjustment "tuning" of the light circuit. There would be two sepparate circuits.  The main larger link tuning circuit for the antenna system and the much smaller light tuning circuit to monitor the link tuning.

What do you think?
Chuck
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flintstone mop
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« Reply #16 on: June 17, 2011, 04:53:43 PM »

Well HEY
Lemme tell you 'bout my feedline woes. I had two RF current meters happily indicating AMPS on my 450 ohm line and when I re-built my antenna / feed line to a 600 ohm system the meters ceased to work any more.
Without mentioning the brand name of the open ladder feed line / antenna. It was one continuous piece of wire that was a ladderline to the shack and turned into an antenna 250 feet (125 feet from center to end). Better signal reports on 160M after the last 5 yrs and the 450 window line and poor solder joints.
So these LED indicators look interesting.

Fred
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Fred KC4MOP
w5gw
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« Reply #17 on: June 17, 2011, 07:20:21 PM »

Joe,

No, not Bud, rather James Millen type.  The ones I have were made in a set with a metal box.  Still have them, still use them.  Also have my Millen GDO which I don't use to much, but broke it out a few months ago to find a trap in my beam that had gone south.

73

Gary
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w5gw
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« Reply #18 on: June 17, 2011, 07:30:20 PM »

Chuck,

As someone pointed out, on open wire feeders there are going to be current nulls and maximums.  So placement (current) is going to be frequency dependent along the line.  All your ideas seem sound - why not just try them and see what happens?  If interested, read up on 'Lecher wires' - basically your feedline is going to have nulls and mamima that are going to be at different distances from the source as frequency change.  For the bands you operate you can, with some experimentation, probably find a spot that will give a reading for all bands.

73

Gary
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aa5wg
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« Reply #19 on: June 17, 2011, 07:55:43 PM »

Fred, Gary and all:

Do you think the neon lights system mentioned above would work?

I ordered both types of lights and have two sizes of sockets for the lights.
The miniture light size socket is an E10 and the other is an E12.

Does anyone know where I can find a quality E10 to E12 converter or adapter?
And, does anyone know where I can find a quality E12 to E10 converter or adapter?

The E12 size is the small candelabra size.
The E10 is the miniture flashlight size.

Chuck
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K1JJ
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« Reply #20 on: June 17, 2011, 09:11:00 PM »

As mentioned earlier by Joe/GMS, the eye's light intensity response is non-linear. To balance two bulbs for brightness is not easy. But there is a solution....

I use the method of placing a 6V bulb on each leg, with maybe an inch of sampling. Brightness is determined by the distance of the span, the power run and the impedance at that point.  Adjust the span running normal power until the bulbs JUST begin to light. You want to see the filament wire burning but not enough to cause a glare. At this point the eye is very sensitive to light intensity variations. You will be surprised how easy it is to balance two lights that are barely lit.

Good luck, OM.

T
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aa5wg
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« Reply #21 on: June 18, 2011, 06:33:56 PM »

K1JJ:
Thank you for your input.
Chuck
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« Reply #22 on: June 18, 2011, 09:37:17 PM »

If you click on it and take it out to the YouTube site, you will see an antenna tuner in the background. There is another video of the antenna tuner that has belt drive roller inductors. Looks like it may be an auto tune type. Not much information on it though? It also looks like it's from the same builder but I think it's in the German language.

The tuner is "just" a fancy L-Network with 2 symmetrical belt driver roller inductors. The switches on the front are different capacitors you can switch in to the circuit. It is a manual tuner. Very nice piece of work!
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