No surprises here....same dumb bad luck....tunas this time

[ka4koe]

First off, are we really surprised?

My brand spanking new antenna is configured as follows:

180' long doublet at 60' high (thanks for the advice again, Tom). Fed with 130' of 600 ohm open wire line (the 130' may be an issue).

The antenna tunes up and works great using my Heathkit SA2060 on 80-20 (haven't tried the higher bands), but the 4:1 voltage balun will not play nice on 160 due to the low Z (about 6 ohms resistive plus a reactive component), which makes the Z the tuna must handle on the order of 2 ohms....NOT GOOD.  MMANAGAL calculated impedance runs....

1.9  6+109j
3.75 86-132j
7.15 65-232j
10.12 83+151j
14.15 2276+51j
18.12 231-744j
21.2 120-128j
28.5 29+258j

I'm using the 2060 on an interim basis until I work up something better......

In the meantime, the balanced tuna project has been derailed due to issues with the roller inductors. Again, not surprised. Roller No. 1 (EF Johnson 28 uH) looked brand new, came with the original box AND destructions. Both end shafts were slightly bent and the sucker would not rotate smoothly. The bend was not enough to be immediately apparent, but enough to gum up the works. Using my GI Joe Kung Fu grip, I was able to carefully bend the shafts back into some semblance of "straight and true-ness". I think this one may be okay.

Roller No. 2 has a different issue. After attaching a knob, the coil would not rotate. At first, I thought the hardware was slipping until I noticed that the shaft was indeed moving but the coil was not.....so it appears the shaft is free rotating. Do I correct this using epoxy or some other adhesive?? The ends of the coil form appear glued on so I'm not sure I want to risk destroying it by attempting disassembly to tighten the shaft hardware within.

Suggestions??? I almost to the point of pitching both rollers and going to homebrew coils with alligator clip leads. I don't want to mod my perfectly good Heapshit Tuna (oxymoron) by converting the internal 4:1 voltage balun to a 1:1 current balun.

GOOD NEWS:

The Valiant is playing nice and receiving good reports on its stock transmit audio. I'm using a cheapo Japanese green crystal bullet mike that folks tell me sounds better than the D104.

Philip KA4KOE

[VE3AJM]

I would just find a good Johnson KW Matchbox for use on 80-10m and build the K1JJ style tuner for 160m. The Johnson Matchbox isn't perfect by any means but using it, and a HB link coupled tuner for 160m would eliminate any need for baluns. That's what I'm doing here. Works FB.

I don't know how those Johnson inductors were procured, but it seems from what you are writing here that you didn't try them out or inspect them before purchase. An online purchase? Can you return them? Getting out to the hamfests is an alternative. Knowing the dealers and local hams who are selling helps too. Bad luck and surprises with buying components can be greatly reduced by buying the stuff in person. It may take a little more time and effort though.

Al VE3AJM

[RolandSWL]

Would the garden variety Johnson Matchbox (non KW) work with the Valiant? It is rated to work with 275 Watts, No?

RSWL.................

[ka4koe]

No, I wish I had. These were internet purchases.

Also, Johnson tunas don't do 160m.

[W2VW]

Fleep, wind yer own, find the setpoints with clipleads and make heavy connections for any bands where high current is expected. This includes highly reactive loads.

I no likey roller inductors for this application.

2VeryWeak.

P.S. Yer signal has a lobe in my direction on 40.

[VE3AJM]

Yes. 2 tuners. The price was right on the KW Matchbox at the time and constructing a tuner for 160m was relatively easy and I had the parts to do it. You may want to have/use/construct 1 tuner for all though. I didn't pass up a Viking 500 because it doesn't cover 160m either.

The Johnson for 80-10m, and the HB tuner for 160m. I use the GPT-750 on 160m as infrequently as I get on there, and the FRT-501 on 80 and 40m with a 160m dipole at 70ft fed with balanced feeders. I have a TMC TAC tuner that will work 160-10m but the present setup works FB as is. Works for me. There are lots of ways to do it of course.

Al VE3AJM

[KL7OF]

Pad the KW matchbox for 160....Good Luck...Steve

[W2VW]

I don't think a KW Matchbox is going to work into a 6 ohm load with any amount of padders.

Years ago I built a few link tuners using BC-610 tank parts. They worked fine and tuned easily on everything but short antenna situations.

[aa5wg]

Philip,

A great way to go is use a link antenna tuner.  No balun to worry about with link tuning.
Plus, you can series or parallel tune your feed system, if needed, dependent upon your
antenna system length. 

Good luck.

Chuck

[K1JJ]

Hi Phil,

Many of your resistive components  listed below seem clustered at low impedance feeds. I would try experimentally adding 45'-55' or so to the feedline and see if you can get some of the lower bands higher.  It will be a compromise across the full spectrum, but certainly the lower bands will match easier if you can pull them up to a higher resistive component.  160M really needs some help raising it above 6 ohms.

Then build a simple link coupled tuner for 160-10M.

T


1.9  6+109j
3.75 86-132j
7.15 65-232j
10.12 83+151j
14.15 2276+51j
18.12 231-744j
21.2 120-128j
28.5 29+258j

[Opcom]

In a bad situation the current could be too much for most rollers and it's clear that a solidly tapped coil has a lot of advantages. For better or worse some of us already already have a few rollers collected, hope we are not wasting a lot of effort. How can one guess or calculate what current a roller can take reliably so a good decision can be made?

#14 wire winding on ceramic form. Spool type roller on a shaft.
5A?

#12 wire on ceramic form - from a BC-939 tuber (BC-610 TX) has a moving solid contact with a braid lead, at least 1/16 sq in of contact area I believe.
10A

3/16" square conductor coil with a very serious sliding contact. Said to be from a 5KW transmitter's antenna tuning section.
20A?

edge wound coil, the spiral winding's cross section about 3/8" by 1/16", with a tight contact that covers about 1/2" square, sliding on the conductor. An AM 10KW BC band 'dog house tuner' coil
20A?

Just guesses. Sorry to be ignorant on it. There should be a way to calculate the current based on the wire size, contact area, and frequency.

[ka4koe]

I was running some numbers yesterday and 20 additional feet brought the 160m Z up. However, the Z everywhere else appears worse.

Other than 160, the venerable SA2060 seems to load it up fine on 80-20m with no issues and no upward creeping VSWR. I need to get out my heat sensor gun and check the balun and roller. I fried the temp probe the other day on my Tek DM43 testing doorknobs in the Valiant.

I made an error in my modeling. Here are the attached revised runs @ 130' and 150' of 600 ohm feed....

[W2VW]

Where is it written 130 feet of balanced line is bad?

What does modeling say with another 20 feet of line on 160?

Probably a good solution for now. That along with losing the 4:1 balun would make a worthwhile difference. Get an rf ammeter in line and do a before and after the balun swap.

[ka4koe]

I revised my post while you were writing yours. I plan on rewiring the balun in the 2060 (easily reversible) to a 1:1 current configuration and trying that on for size.

[K3ZS]

130 ft of feedline is about 1/4 wavelength transformer for 160M.   High impedance and one end is transformed to a low impedance at the other.

[W2VW]

130 ft of feedline is about 1/4 wavelength transformer for 160M.   High impedance and one end is transformed to a low impedance at the other.

Right. Which makes one wonder the figure for impedance at the antenna feedpoint on 160. 180' center fed should be fairly low resistive with a fair amount of capacitive reactance.

Maybe I need more coffee but the 130 foot line is not putting the impedance where I would figure.

[W2VW]

In a bad situation the current could be too much for most rollers and it's clear that a solidly tapped coil has a lot of advantages. For better or worse some of us already already have a few rollers collected, hope we are not wasting a lot of effort. How can one guess or calculate what current a roller can take reliably so a good decision can be made?

Lots of missing information to find with rollers. GIGO.

Roller inductors do funny things at low inductance values. Q falls off. Shorted turns, all the extra metal close to the coil and unknown current capability of contacts make it a good place to experiment instead of calculate.

Careful measurement of rf current at tuner output port tells the tale.

The BC-939 coils I had were #16 material and did not do well with a 160' center fed antenna with 110 feet of feeder. They made considerable amounts of heat at QRO. Replaced with ice maker water supply line hand wound coils.

Rollers work great in some applications but not so well in this one unless giant ones in good condition are used. 

[ka4koe]

Ahhh, selected wrong conductor. Had "lossless" selected instead of "CU". The Z on 160 spits out 28+j704. Need to check this against MININEC.

[Opcom]

In a bad situation the current could be too much for most rollers and it's clear that a solidly tapped coil has a lot of advantages. For better or worse some of us already already have a few rollers collected, hope we are not wasting a lot of effort. How can one guess or calculate what current a roller can take reliably so a good decision can be made?

Lots of missing information to find with rollers. GIGO.

Roller inductors do funny things at low inductance values. Q falls off. Shorted turns, all the extra metal close to the coil and unknown current capability of contacts make it a good place to experiment instead of calculate.

Careful measurement of rf current at tuner output port tells the tale.

The BC-939 coils I had were #16 material and did not do well with a 160' center fed antenna with 110 feet of feeder. They made considerable amounts of heat at QRO. Replaced with ice maker water supply line hand wound coils.

Rollers work great in some applications but not so well in this one unless giant ones in good condition are used. 

Well yeah that is the problem. Way too many variables, even a set of them for each frequency and at each inductance (or 'turns' would be a better way to specify it). I was hoping for a simple rule of thumb, as used with transformer cores. No problem, experiments are fine by me, only it takes me a long time to set them up, and this one would mean building the massive tuner.

OK I must have mis-eyeballed the big inductor in the -939. I have two, therefore included it in the list. I so have two of the 'square wire' ones and two of the BC-rated ones. I don't want this side matter/question to detract from the original topic which is very important.

[Opcom]

I was running some numbers yesterday and 20 additional feet brought the 160m Z up. However, the Z everywhere else appears worse.

What modeling software do you use?

I have tried the free version of eznec but it is inadequate for my somewhat odd antenna.
And not very intuitive in making the model, that is, I have trouble specifying just where in space the ends are, much less trying to attach a feed line to it.
- a slanted 30FT wire starting at coordinates XYZ does not end 30FT from X, Y, or Z. - what a headache. I only know the length of the wire, height at center, and height at the end.

I want something better and simple to use, maybe even if I have to buy it. but not real expensive.

[K4RT]

Pad the KW matchbox for 160...

In my experience the SA2060 tuner is marginal on 160M, especially if running high power. I don't recall the feedpoint impedance of my 160M antenna at our previous home, but adding padder caps to the SA2060's "antenna matching" variable cap improved loading and made it possible to run a KW on Top Band.

In regard to the figures for your antenna, did you use an antenna analyzer to determine the impedance for each band?  Is your antenna resonant on any band(s) without the tuner?

[aa5wg]

Philip,

I got tired of heating baluns with certain bands not working.

Building the link antenna tuner got rid of 99% of those negatives.  If, in the rare case the antenna system would not tune up, with either series or parallel configuration, I would then shunt some capacitive or inductive reactance across the feeders, in the shack, and bang I was on the air.  

Chuck

[ka1bwo]

Hi Phil,
Phil Smith has a white paper showing different networks, L low pass, L high pass,
Pi, etc. It shows graphically each type network and the range of input impedance that can be transformed to 50 ohm and the forbidden zone of input impedance that can't. It also shows the effects of cascading the networks for the impedance range of interest for your antenna network design.
Joe     


 

First off, are we really surprised?

My brand spanking new antenna is configured as follows:

180' long doublet at 60' high (thanks for the advice again, Tom). Fed with 130' of 600 ohm open wire line (the 130' may be an issue).

The antenna tunes up and works great using my Heathkit SA2060 on 80-20 (haven't tried the higher bands), but the 4:1 voltage balun will not play nice on 160 due to the low Z (about 6 ohms resistive plus a reactive component), which makes the Z the tuna must handle on the order of 2 ohms....NOT GOOD.  MMANAGAL calculated impedance runs....

1.9  6+109j
3.75 86-132j
7.15 65-232j
10.12 83+151j
14.15 2276+51j
18.12 231-744j
21.2 120-128j
28.5 29+258j

I'm using the 2060 on an interim basis until I work up something better......

In the meantime, the balanced tuna project has been derailed due to issues with the roller inductors. Again, not surprised. Roller No. 1 (EF Johnson 28 uH) looked brand new, came with the original box AND destructions. Both end shafts were slightly bent and the sucker would not rotate smoothly. The bend was not enough to be immediately apparent, but enough to gum up the works. Using my GI Joe Kung Fu grip, I was able to carefully bend the shafts back into some semblance of "straight and true-ness". I think this one may be okay.

Roller No. 2 has a different issue. After attaching a knob, the coil would not rotate. At first, I thought the hardware was slipping until I noticed that the shaft was indeed moving but the coil was not.....so it appears the shaft is free rotating. Do I correct this using epoxy or some other adhesive?? The ends of the coil form appear glued on so I'm not sure I want to risk destroying it by attempting disassembly to tighten the shaft hardware within.

Suggestions??? I almost to the point of pitching both rollers and going to homebrew coils with alligator clip leads. I don't want to mod my perfectly good Heapshit Tuna (oxymoron) by converting the internal 4:1 voltage balun to a 1:1 current balun.

GOOD NEWS:

The Valiant is playing nice and receiving good reports on its stock transmit audio. I'm using a cheapo Japanese green crystal bullet mike that folks tell me sounds better than the D104.

Philip KA4KOE

[ka1bwo]

Phil,
For 160 meters if you install a 500pf capacitor across the shack end of the feed line it will transpose the impedance from 6+j109 to 50+j308 A 560pf would transpose 6+109j to 79+j388  I would think the Heath SA2060 could deal with that. Hope this helps
Joe

First off, are we really surprised?

My brand spanking new antenna is configured as follows:

180' long doublet at 60' high (thanks for the advice again, Tom). Fed with 130' of 600 ohm open wire line (the 130' may be an issue).

The antenna tunes up and works great using my Heathkit SA2060 on 80-20 (haven't tried the higher bands), but the 4:1 voltage balun will not play nice on 160 due to the low Z (about 6 ohms resistive plus a reactive component), which makes the Z the tuna must handle on the order of 2 ohms....NOT GOOD.  MMANAGAL calculated impedance runs....

1.9  6+109j
3.75 86-132j
7.15 65-232j
10.12 83+151j
14.15 2276+51j
18.12 231-744j
21.2 120-128j
28.5 29+258j

I'm using the 2060 on an interim basis until I work up something better......

In the meantime, the balanced tuna project has been derailed due to issues with the roller inductors. Again, not surprised. Roller No. 1 (EF Johnson 28 uH) looked brand new, came with the original box AND destructions. Both end shafts were slightly bent and the sucker would not rotate smoothly. The bend was not enough to be immediately apparent, but enough to gum up the works. Using my GI Joe Kung Fu grip, I was able to carefully bend the shafts back into some semblance of "straight and true-ness". I think this one may be okay.

Roller No. 2 has a different issue. After attaching a knob, the coil would not rotate. At first, I thought the hardware was slipping until I noticed that the shaft was indeed moving but the coil was not.....so it appears the shaft is free rotating. Do I correct this using epoxy or some other adhesive?? The ends of the coil form appear glued on so I'm not sure I want to risk destroying it by attempting disassembly to tighten the shaft hardware within.

Suggestions??? I almost to the point of pitching both rollers and going to homebrew coils with alligator clip leads. I don't want to mod my perfectly good Heapshit Tuna (oxymoron) by converting the internal 4:1 voltage balun to a 1:1 current balun.

GOOD NEWS:

The Valiant is playing nice and receiving good reports on its stock transmit audio. I'm using a cheapo Japanese green crystal bullet mike that folks tell me sounds better than the D104.

Philip KA4KOE

[W2VW]

Philip,

I got tired of heating baluns with certain bands not working.

Building the link antenna tuner got rid of 99% of those negatives.  If, in the rare case the antenna system would not tune up, with either series or parallel configuration, I would then shunt some capacitive or inductive reactance across the feeders, in the shack, and bang I was on the air.  

Chuck,

     Phil is planning on building an antenna coupler with the balun on the input side of the tuning network. We pretty much all know baluns do not play well on the output side in many situations.

Are you saying you have heated baluns using them at their design impedance with minimal or no reactance in the load?

73,
Dave