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Re: Toroid Ferrite Loop Stick

Rik
 

As I try to read articles here, it looks like combining coils is not like combining speakers. It looks like the uH does not change the same way, and I see no obvious way to predict results at all. Is it entirely determined by experimenting and measuring uH with a meter? - FARMERIK


Re: Toroid Ferrite Loop Stick

Rik
 

So it sounds like the 4 coil Polydorf would have all four coils about the target uH, giving lots of Litz to pick up signals, but I would have to choose one uH if I stayed with a series/parallel 4 coil connection.

I do want to use this antenna  both tuned by a cap and tuned by the PL-360 radio which wants a higher uH of 350. So I am thinking of dividing the 350 uH into 2 or 3 coils in series, and then connecting all 3, or only 2 or just one for the Tropical bands.

[ I don't happen to be interested in LW, as my BOG does that very well for EU broadcasters, and I am not interested in NDB where the directional ability of a loop would be welcome, but others here are.]

Connecting 2 coils in  series or in  parallel gives a 4:1 change in uH. I don't know, but I would think it more likely to end up with a gap in coverage. Choosing the number of coils in series gives much closer steps with more overlap.

If I had all the various coils I might like wound on a sleeve I could slide  it over the 'stack' of toroids, I could use the same set of ferrite for  many configurations.

My earlier plan was to attach the coils to just the toroids under them, and then I could completely remove unused coils, and try different spacings between coils with different numbers of toroids without coils wound on them. Also, by flipping over a coil I could reverse the winding pattern or not, and have all coils wind in the same direction, or every other one  change as Polydorf Patented.

If both schemes would work, I still would have to choose one way or the other.  So that is my question now. - FARMERIK


Re: Optimal uH for PL-360 on AM?- Gary DeBock?

Gary DeBock
 

Hello Farmerik,
 
The PL-360 MW plug-in loopsticks use 58 turns of 40/44 Litz wire centered on an Amidon 7.5" Type 61 ferrite rod, for a coil inductance of 350 uH. The related article is posted at http://www.mediafire.com/view/2cqwsqj0bvajf6k/7.5_inch-LS.doc
 
73, Gary DeBock (in Puyallup, WA, USA) 
 
 
 

-----Original Message-----
From: farmerik@... [ultralightdx]
To: ultralightdx
Sent: Mon, Nov 9, 2015 5:54 am
Subject: [ultralightdx] Optimal uH for PL-360 on AM?- Gary DeBock?

 
Remember the ferrite antennas you made for my PL-360 which plugged in the top? What value of uH did the PL-360 like best tuning the AM BCB? - FARMERIK


Re: Toroid Ferrite Loop Stick

Everett N4CY
 

If you are using the Polydoroff configuration, then YES. Now that you are increasing the length of the rod, you should be able to use a 4 coil Polydoroff configuration. If you are wanting to make it a dual band, then you would want 3 coils, however, you might get by with two coils for a dual band, in series for the lower frequencies and in parallel for the higher frequencies.
 
Everett N4CY
 

In a message dated 11/9/2015 7:42:19 A.M. Central Standard Time, ultralightdx@... writes:
 

Would you think multiple coils in series are significantly better than one winding, or just a little better? -FARMERIK


Optimal uH for PL-360 on AM?- Gary DeBock?

Rik
 

Remember the ferrite antennas you made for my PL-360 which plugged in the top? What value of uH did the PL-360 like best tuning the AM BCB? - FARMERIK



Re: Toroid Ferrite Loop Stick

Rik
 

Would you think multiple coils in series are significantly better than one winding, or just a little better? -FARMERIK


Re: Toroid Ferrite Loop Stick

Everett N4CY
 

You do not need to glue, or space the toroids, I have tried it both ways. Just get a 1" dia dowel rod and cut it just slightly shorter than the total length of the 18 stacked toroids. Then use wood, or plastic disk the ends of the dowel rod to hold and compress the toroids (The disk can be screwed on). 

Based on my experiments it appeared that, by doing the above, that the combined toroids looked as though they were one solid rod. I base this assumption on looking at the induction readings of a coil being moved from one end of the rod to the other. The induction is less on each end and higher in the middle of the rod, which is the same thing that I saw on a solid bar. 

When you wind the 3 coils, you will need to use less turns on the middle coil in order to try to keep the inductance the same for each coil. 

Everett N4CY


On Nov 9, 2015, at 2:58 AM, farmerik@... [ultralightdx] <ultralightdx@...> wrote:

 

I couldn't help myself and ordered 8 more toroids. My plan is to have 3 coils wound which will have a total uH in series for AM. I think those windings will cover 2 toroids, but 3 would be fine too. Those sets of 2 or 3 toroids I'll glue or tape together, and then use most of the rest as spacers which can be arranged in different patterns. For example, in one of Everetts tests he found a 5-6 inch spacing between coils worked best on a FSL. So I could slide one coil set on the core, then 3 spacer toroids, then the second coil the other side 'up' so the turns go in the opposite direction, then 3 more spacers and then the 3rd coil and finally one toroid with a pick up coil at the end. If all 18 toroids work very well together, that is fine. If the extra length is not that big an advantage, I could make a smaller version with a single coil out of the extras. It will be quite a while before I can get this all done. I like the fact it will be a test bed whi ch can be modified easily by just rearranging the coils and spacers on a 1 inch rod.  - FARMERIK


Re: Toroid Ferrite Loop Stick

Rik
 

I couldn't help myself and ordered 8 more toroids. My plan is to have 3 coils wound which will have a total uH in series for AM. I think those windings will cover 2 toroids, but 3 would be fine too. Those sets of 2 or 3 toroids I'll glue or tape together, and then use most of the rest as spacers which can be arranged in different patterns. For example, in one of Everetts tests he found a 5-6 inch spacing between coils worked best on a FSL. So I could slide one coil set on the core, then 3 spacer toroids, then the second coil the other side 'up' so the turns go in the opposite direction, then 3 more spacers and then the 3rd coil and finally one toroid with a pick up coil at the end. If all 18 toroids work very well together, that is fine. If the extra length is not that big an advantage, I could make a smaller version with a single coil out of the extras. It will be quite a while before I can get this all done. I like the fact it will be a test bed which can be modified easily by just rearranging the coils and spacers on a 1 inch rod.  - FARMERIK


Re: Toroid Ferrite Loop Stick

Everett N4CY
 

I did not experiment with a pick up coil on the one using that 2" dia toroids. However, if you will look back at some on my past articles I have info on using a coupling transformer using binocular cores BN202-73 using, I think, a 36:1 ratio. This keeps you from loading the tuned circuit, thus keeping you from screwing up the Q. 

Everett N4CY


On Nov 8, 2015, at 9:01 AM, farmerik@... [ultralightdx] <ultralightdx@...> wrote:

 

Another question about your [Eversharp's] new anteena wound on Toroids, have you experimented with a pick up coil, and if so what worked best to connect directly to a radio.

I guess the usual way is 3-5 turns to match 50 Ohms or so, but what ever number of turns works best.

-FARMERIK


Re: Toroid Ferrite Loop Stick

Rik
 

Another question about your [Eversharp's] new anteena wound on Toroids, have you experimented with a pick up coil, and if so what worked best to connect directly to a radio.

I guess the usual way is 3-5 turns to match 50 Ohms or so, but what ever number of turns works best.

-FARMERIK


Re: anyone using a loop for tropical bands?

josephrot
 

RE: << Is anyone here using any type of loop antenna on the lower frequencies of SW? -FARMERIK >>

Well, I have not specifically sat a long time-and-DX tuned the "tropical band" -- but likely tuned through it...:)..

I have been experimenting in some off time using a 30 inch / 76 cm box loop antenna that I utilize for high LW and MW uses...currently mounted indoors high-up (NOT in my basement for sure), I am wanting to weather-proof the loop and someday soon mount it outside on a rotor pole at the roof eve, expecting the loop performance to be even better.
 
Even without specifically altering the loops LW/MW L/C,  the loop's 2 MHz through 5 MHz performance is increased over, say, a 66ft Windom dipole or even the trusted 45ft slanted T2FD that's used for 3 through 30 MHz general listening. The performance increase is a little spotty, with a peak noted here and there, and the level of increase is not "phenomenal", but averages maybe two S units on both Satellit 800 and SDR receivers.

And yes, the "rotate-ability" of the loop is most welcome, as I can usually null out / reasonably well reduce noise, sometimes affect propagation effects slightly, etc. Yet, yes, the indoor RF / EMI "pollution" is low-to-moderate as well.

Finally, more because I am used to it more, I run coax from the loop to receivers, with an optional earth ground to judge effects of grounding the loop. 

Hope this is useful report...

Joe Rotello / Knoxville, TN / USA


 


Re: anyone using a loop for tropical bands?

Richard Jones
 

My homemade Palstar clone and Quantum clone loopstick tunes up to 2MHz. If my location was only quiet enough to hear anything <sigh>! Maybe some day...!


Re: anyone using a loop for tropical bands?

osage_archer
 

I'm using a Wellbrook ALA1530 right now, listening to 5070 kHz and it does great even for the AM BCB.  I can even listen to the FM BCB pretty well although they say the range is 50 kHz - 30 MHz.

If I was limited to just one antenna, the Wellbrook would be the one.

Tim


anyone using a loop for tropical bands?

Rik
 

Is anyone here using any type of loop antenna on the lower frequencies of SW? -FARMERIK



Re: Toroid Ferrite Loop Stick

Everett N4CY
 

A 2 coil Polydorff might be a good option. It will take a little more than just one coil. 

Everett N4CY


On Nov 6, 2015, at 7:43 PM, farmerik@... [ultralightdx] <ultralightdx@...> wrote:

 

Sounds like it should make a very interesting antenna for me. I should have enough 660/46 Litz left over from the special low uH antenna for the Fisher AM 80 which I am having made on a 12 inch X 1/2 inch ferrite. I sent your article from this site regarding multi coil antennas and Polydorf. I hope to get him to wind at least two coils I can parallel for a reasonable number of turns at around only  46 uH total for the Fisher. If he does that, I could also connect them in series for the Tropical bands + tuned with a cap.

If that works well, I may ask him to separate the toroids and space them apart with separate coils to see if it is more directional, but that is just a wild guess that it might be. Anyone have ideas about that?

I did not bother make a bid for a lower price.

-FARMERIK


Re: Toroid Ferrite Loop Stick

Rik
 

Sounds like it should make a very interesting antenna for me. I should have enough 660/46 Litz left over from the special low uH antenna for the Fisher AM 80 which I am having made on a 12 inch X 1/2 inch ferrite. I sent your article from this site regarding multi coil antennas and Polydorf. I hope to get him to wind at least two coils I can parallel for a reasonable number of turns at around only  46 uH total for the Fisher. If he does that, I could also connect them in series for the Tropical bands + tuned with a cap.

If that works well, I may ask him to separate the toroids and space them apart with separate coils to see if it is more directional, but that is just a wild guess that it might be. Anyone have ideas about that?

I did not bother make a bid for a lower price.

-FARMERIK


Re: Toroid Ferrite Loop Stick

Everett N4CY
 

The spacing was the same that I used in the article that wrote and at the time worked out to be the best option. The tuning was sharp, indicating high Q and the loop rotation was quite sharp also. 

What price did you get them for?

Everett N4CY


On Nov 6, 2015, at 7:13 PM, farmerik@... [ultralightdx] <ultralightdx@...> wrote:

 

I'm in. I just ordered 5 pairs of those toroids. I hope my repair guy will wind them for me.

How did you decide the thickness of the spacer between the winding and the toroids?

With Litz, are you getting high Q sharp tuning?

-FARMERIK


Re: Toroid Ferrite Loop Stick

Rik
 

I'm in. I just ordered 5 pairs of those toroids. I hope my repair guy will wind them for me.

How did you decide the thickness of the spacer between the winding and the toroids?

With Litz, are you getting high Q sharp tuning?

-FARMERIK


Re: Toroid Ferrite Loop Stick

Everett N4CY
 

Sorry, but since I don't have a solid ferrite rod that size to compare it to, nor would I want to pay the price such a rod, I can't answer you question. I can tell you that it is much better than the stack toroid rod that I wrote about that using the FT140-61 toroids. 
I was quite surprised at how well it the stacked toroid loop worked compared to 1 meter air loop. I probably will not do any more experiments with this as a receiving loop, as my plan is to experiment with using it as a transmitting loop.  I plan on placing the toroids on a copper pipe, rather than a wood dowel rod, so I can do some cooling. I have been operating a lot of JT65, which allows you to DX with very low power. I bough 46 of the toroids so I can build several ferrite transmit loops. 

I don't know how long the supply of the toroids will last. I think that if you offered the eBay supplier $35 to $40 delivered for 10 toroids he will take the offer. They are not a standard size, but are made by Fair-Rite, whom is a high end manufacture of ferrite. You would normally pay $10 a pice, or more for a toroid like that. The inductance for ten turns of wire on a FT240-61, which is the largest core that Fair-Rite makes in that mix, is 20uH and it weights about 106 gm, the toroids that the eBay seller is offering have a inductance of 36uH and weigh 136 gm.  

Everett N4CY (new call)


On Nov 6, 2015, at 9:47 AM, farmerik@... [ultralightdx] <ultralightdx@...> wrote:

 

I am impressed with a ferrite loop which compares so well to such a large air core loop. I have followed a number of articles available on line, including yours in the files section of this group about multi coil ferrite antennas. Do you have any conclusions that the stack of hollow ferrites is better than a single huge ferrite, or is it less expensive? - FARMERIK


Re: Toroid Ferrite Loop Stick

Rik
 

I am impressed with a ferrite loop which compares so well to such a large air core loop. I have followed a number of articles available on line, including yours in the files section of this group about multi coil ferrite antennas. Do you have any conclusions that the stack of hollow ferrites is better than a single huge ferrite, or is it less expensive? - FARMERIK

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