Re: [Elecraft] Balun Questions

Yes, insulation does in effect cause the electrical length to change. Case and point, construct a 1/2 wave antenna using insulated wire, put it up and determine the resonant frequency or point where the SWR is 1:1. Then take it down, carefully strip off the insulation and put it back in the

Re: [Elecraft] Balun Questions

Hi Jim, I have been reading about your exploits with THHN, and the 100 to 50 ohm change caused by the insulation...  I am going to pick some up today and wind a choke using it, (as opposed to enameled 14 GA copper), to see just how close to 50 ohms it will come...  Any last minute tips?  BTW,

Re: [Elecraft] Balun Questions

Hi Bob McGraw, I agree, except on one point: I’s say 90%, rather than 75%, of the stuff we use and methods employed would put most of the station stuff in the trash. 73, Bob Nobis - N7RJN n7...@nobis.net > On Feb 9, 2016, at 08:01, Bob McGraw K4TAX wrote: > > I'm one

Re: [Elecraft] Balun Questions

Hi Bob, et al, Thank you all for your careful attention. I read it wrong, as several have pointed out overnight. I transposed that to a percentage in my memory after reading it. One of the reasons for referring people to the original material in these cases. Someone will get it right. That

Re: [Elecraft] Balun Questions

I'm one of the other Bob's or Robert's Since the assembly of coax wound around a toroid doughnut style bobbin is typically not exposed to vibration, such as might exist in an airplane, boat or space vehicle, the use of a solid conductor coax such as RG-303 would not seem to be of

Re: [Elecraft] Balun Questions

Hello Bob, The coax could be exposed to heat when in service as a balun, so I would respectfully disagree with you on this one point. If you exceed the bending radius of your coax, you stand a higher percentage chance of causing a shield to center connector short, (due to center conductor

Re: [Elecraft] Balun Questions

If one has heating issues to that magnitude, they have other more critical issues which should be addressed. Bob, K4TAX Sent from my iPhone > On Feb 9, 2016, at 9:24 AM, Dave Cole wrote: > > Hello Bob, > > The coax could be exposed to heat when in service as a balun, so I >

Re: [Elecraft] Balun Questions

I have addressed this by showing photographs of winding techniques for coax normally used for transmitting, and for short lengths of transmission line formed by taping together a pair of 4-6 ft of #12 THHN. There's also text that goes with it, noting that winding radius should follow mfr

Re: [Elecraft] Balun Questions

Thank you Bob... -- 73's, and thanks, Dave For software/hardware reviews see: http://www.nk7z.net For MixW support see: https://groups.yahoo.com/neo/groups/mixw/info For SSTV help see: http://groups.yahoo.com/neo/groups/MM-SSTV/info On Tue, 2016-02-09 at 14:28 -0600, Bob McGraw K4TAX wrote:

Re: [Elecraft] Balun Questions

On Tue,2/9/2016 11:46 AM, Dave Cole wrote: Hi Jim, I have been reading about your exploits with THHN, and the 100 to 50 ohm change caused by the insulation... Note that my observations are confirming results published several decades ago by Jerry Sevick, W2FMI. My observations of Zo and Vf

Re: [Elecraft] Balun Questions.

On 09/02/16 17:15, elecraft-requ...@mailman.qth.net wrote: > If you lose, it is never good when the center conductor shorts to the >shield at Kilowatt power levels. Use loops large enough to stay within >the bending radius of your coax. Now if this is QRP, you could >probably get away with

Re: [Elecraft] Balun Questions.

Hi Dave G0WBX, I used to deal with some of those prior to retirement, worked in a broadcast shop for about 40 years...  What a difference digital has made to TV broadcast! :) -- 73's, and thanks, Dave For software/hardware reviews see: http://www.nk7z.net For MixW support see:

Re: [Elecraft] Balun Questions

ectric. --- Chuck, AE4CW From: Mel Farrer [mailto:farrerfo...@yahoo.com] Subject: Re: [Elecraft] Balun Questions SORRY, but the min static bending radius for RG-303 is 25 mm and RG-400 is 35 mm. For torroid wrap which is better? __

Re: [Elecraft] Balun Questions

On Mon,2/8/2016 2:52 PM, Mel Farrer via Elecraft wrote: Let's do some basic thinking. Mel, You need to study my tutorial. Common mode chokes are NOT inductors, they are parallel resonant circuits, and it is their resistive impedance at resonance that makes the choke effective. 73, Jim

Re: [Elecraft] Balun Questions

Hi Guy, Thank you. It is interesting that the ANSI test is based on physical “outer surface" deformity, rather than electrical (rf) performance. Although there is probably a degree of correlation between physical deformity and electrical (rf) performance. I agree the ANSI spec outlines a

Re: [Elecraft] Balun Questions

This doesn't answer your details, but what I did to test the one I made was simply to compare it to the balun in my manual roller inductor tuner. I used a short coax jumper between the tuner and the homebrew balun. Dick, n0ce On 2/6/2016 12:06 PM, Jim Allen wrote: Ok, so this morning, I went

Re: [Elecraft] Balun Questions

.    Funn. Mel, K6KBE From: Richard Fjeld <rpfj...@outlook.com> To: elecraft@mailman.qth.net Sent: Monday, February 8, 2016 12:57 PM Subject: Re: [Elecraft] Balun Questions This doesn't answer your details, but what I did to test the one I made was simply to c

Re: [Elecraft] Balun Questions

Robert Nobis wrote: > After reviewing specs from several manufacturers, the “recommended” minimum bend radius for RG303 and RG400 is essentially the same at 1.0 inches. Hi Robert, I have wrapped RG400 on a two stack of FT240 form factor toroids with never an issue, without any change in

Re: [Elecraft] Balun Questions

At 01:07 AM 2/7/2016, K2AV wrote: I also came by bundles of miscellaneous 6 foot to 15 foot jumpers with various connectors on end for similar ridiculous low prices per foot. In the last few years I have found similar RG400 jumpers at the Dayton Hamvention at quite reasonable prices. Since I

Re: [Elecraft] Balun Questions

:08 To: Robert Nobis <n7...@nobis.net> Cc: elecraft@mailman.qth.net; Ron D'Eau Claire <r...@cobi.biz>; Guy Olinger K2AV <k2av@gmail.com> Subject: Re: [Elecraft] Balun Questions RG303 is not rated for the tight bends. RG400 with its fine stranded center conductor is rate

Re: [Elecraft] Balun Questions

?? > > Mel, K6KBE > > > From: Chuck Catledge <ae...@att.net> > To: 'Guy Olinger K2AV' <k2av@gmail.com>; 'Robert Nobis' <n7...@nobis.net> > Cc: elecraft@mailman.qth.net; 'Ron D'Eau Claire' <r...@cobi.biz> > Sent: Sunday, February 7, 2016 2:31 PM

Re: [Elecraft] Balun Questions

th.net; 'Ron D'Eau Claire' <r...@cobi.biz> Sent: Sunday, February 7, 2016 2:31 PM Subject: Re: [Elecraft] Balun Questions At hamfests around the Southeast, surplus RG400 is often found in terminated cables (usually BNC or N) in lengths up to around 20 feet.  The price I've paid is al

Re: [Elecraft] Balun Questions

net>; 'Guy Olinger K2AV' <k2av@gmail.com>; 'Robert Nobis' <n7...@nobis.net> Cc: elecraft@mailman.qth.net; 'Ron D'Eau Claire' <r...@cobi.biz> Subject: Re: [Elecraft] Balun Questions SORRY, but the min static bending radius for RG-303 is 25 mm and RG-400 is 35 mm.

Re: [Elecraft] Balun Questions

rd 3” and greater due to the foam dielectric. --- Chuck, AE4CW From: Mel Farrer [mailto:farrerfo...@yahoo.com] Subject: Re: [Elecraft] Balun Questions SORRY, but the min static bending radius for RG-303 is 25 mm and RG-400

Re: [Elecraft] Balun Questions

I just completed a 160/80M common mode choke made from 6 type 31 cores. Each core is 1/2" inside diameter, 1" outside diameter, and 1" long. (12.5mm, 25mm, 25mm). There are four windings of RG58 and I think this design is in agreements with Jim Brown, K9YC's RFI-ham.pdf. The choke hangs just

Re: [Elecraft] Balun Questions

Almost all of G3TXQ's tests on his website with ferrite core baluns involved RG58, so I figured RG8X would be even better. I have a lot of it, and no RG58. Luckily, these things are easy to work with, so if I ever have/want/need to change it, it's so easy even a lawyer can do it, 3 out of 5

Re: [Elecraft] Balun Questions

Bob makes an excellent point. I've seen cases where even "solid" dielectric did that over time because, after all, it is not really solid. The dielectric is plastic so the coax can be bent. All coax has a minimum bending radius specification. Specific data is available on line but, in general,

Re: [Elecraft] Balun Questions

- Original Message - From: "Ron D'Eau Claire" <r...@cobi.biz> To: <elecraft@mailman.qth.net> Sent: Saturday, February 06, 2016 10:33 PM Subject: Re: [Elecraft] Balun Questions Bob makes an excellent point. I've seen cases where even "solid" dielectric d

Re: [Elecraft] Balun Questions

If one wants a small 50 ohm coax that will take QRO with a very large margin and was *designed* for bending and use in aircraft wiring harnesses then use RG400 to wind around your core. RG400 uses a fine stranded silvered copper center conductor that is more flexible than its Teflon dielectric. It

Re: [Elecraft] Balun Questions

On Saturday, February 6, 2016, Jim Allen wrote: > I used RG8X coax, a 2.4" core, not sure exactly what mix, and 11 turns. > There is a *huge* variation in core materials and performance specifics found in the FT241 form factor. It really matters what the actual

Re: [Elecraft] Balun Questions

Ok, so this morning, I went out to the shack and whipped up a balun, from a G3TXQ design I found on the website of W5DXP.com. It is coax wrapped around a ferrite core, with appropriate connectors in a plastic weathertight box. I used RG8X coax, a 2.4" core, not sure exactly what mix, and 11

Re: [Elecraft] Balun Questions

If you're driving a 50 ohm load, then the cable wound around the core is just an extension of the transmission line and has no impedance modifying effects. The significant parameter is the common mode (CM) impedance. G3TXQ discusses a way to measure it here:

Re: [Elecraft] Balun Questions

I would have concern that long term usage of RG-8X, being foam core dielectric material and bent in a tight radius, may allow the center conductor to migrate to the inside radius of the bend. The Minimum Bend Radius for RG-8X is 2.50". Thus the tight bend will allow the center conductor

Re: [Elecraft] Balun Questions

Yep, good stuff. Be sure of your budget before buying a roll. It is a bit pricey. Handles legal limit HF power with a reasonable SWR. 73 Bob, K4TAX On 2/6/2016 7:10 PM, Robert Nobis wrote: I have used RG303/U for chokes. A bit smaller diameter than RG400 (0.170 versus 0.195 inches).

Re: [Elecraft] Balun Questions

I can second Jim's concern about have one's work usurped by another. I can recall Googling a topic and having a paper come up on some Canadian's website that appeared to be written by him but in fact was my ladderline paper. I emailed him and asked him nicely to remove it and simply link to

Re: [Elecraft] Balun Questions

Guy, After reviewing specs from several manufacturers, the “recommended” minimum bend radius for RG303 and RG400 is essentially the same at 1.0 inches. 73, Bob Nobis - N7RJN n7...@nobis.net > On Feb 6, 2016, at 23:07, Guy Olinger K2AV wrote: > > RG303 is not rated

Re: [Elecraft] Balun Questions

Bob, Yes, it is a bit expensive: $2.91 per foot from “The Wireman” plus shipping. (For lengths under 100 feet.) 73, Bob Nobis - N7RJN n7...@nobis.net > On Feb 6, 2016, at 18:21, Bob McGraw K4TAX wrote: > > Yep, good stuff. Be sure of your budget before buying a

Re: [Elecraft] Balun Questions

A favorite of mine for transmission line transformers or common-mode chokes (a.k.a. "baluns") is to use a twisted pair instead of coax. Cheap and effective and with a little calculation you can approximate any impedance line you want. K2 builders know this technique from winding T6 in their

Re: [Elecraft] Balun Questions

I have used RG303/U for chokes. A bit smaller diameter than RG400 (0.170 versus 0.195 inches). RG303/U has a solid copper center conductor that is silver plated. The shield for RG303 is also silver plated copper. The jacket is Class 9 Teflon. Also the dielectric material is teflon. 73, Bob

Re: [Elecraft] Balun Questions

RG303 is not rated for the tight bends. RG400 with its fine stranded center conductor is rated for corner bends in aircraft wiring harnesses and will not deform the dielectric within the bends. I would not wind any solid center conductor coax on a toroid. I would only buy cut lengths of RG400

Re: [Elecraft] Balun Questions

Wow, that is eye opening! I always thought I was just lazy/cheap when I merely polished my amplifier tank coils and sprayed them with clear plastic (Krylon), but it seems I was doing the right thing after all. Vic 4X6GP/K2VCO > On 7 Feb 2016, at 3:48 AM, Wes (N7WS) wrote: >

Re: [Elecraft] Balun Questions

On Sat,2/6/2016 4:33 PM, Jim Allen wrote: Almost all of G3TXQ's tests on his website with ferrite core baluns involved RG58, so I figured RG8X would be even better. I have a lot of it, and no RG58. Did you study the material on my website? My measurement method is clearly described in

Re: [Elecraft] Balun Questions

On oft repeated myth. See: http://k6mhe.com/n7ws/Plating.pdf On 2/6/2016 5:49 PM, Guy Olinger K2AV wrote: That's silvered strands whose silver sulphide patina or tarnish is conductive as opposed to the green copper sulphate that separates copper strands that have been water soaked.

Re: [Elecraft] Balun Questions

On Fri, 30 Jul 2010 19:35:50 -0700, Brett Howard wrote: Where be your tutorial? http://audiosystemsgroup.com/RFI-Ham.pdf I've got a couple 4 #2 cores Cores are NOT mix and match. It took me YEARS to find this particular sweet spot. If you want a decent balun, you must either follow the

Re: [Elecraft] Balun Questions

On Fri, 23 Jul 2010 11:53:33 -0700, Brett Howard wrote: Interesting enough his high power one uses two cores and appears to be made the same as the budget one that is wound on one core... Seems like stacking them on top of one another is going to just couple them and hinder your isolation but

Re: [Elecraft] Balun Questions

Where be your tutorial? I've got a couple 4 #2 cores that I was thinking of using... Not sure if it'll be the right material but they sure are big enough that I shouldn't have to worry about power handling! ;) It'll probably be a bit before I get to building the Balun project. I'm in the

[Elecraft] Balun Questions

I'll preface this by explaining that I'm a digital guy and I've lately decided I want to get a little better understanding of magnetics and RF... Thus why I'm taking on making my own W3NQN band pass filters and I've also been interested in building a Balun... So I've looked at a few sites

Re: [Elecraft] Balun Questions

So I've looked at a few sites describing how to make a 4:1 balun... One such solution is to take 2 100 ohm 1:1 baluns and connect them in parallel on the input side and in series on the output side... The 100 ohms is the differential impedance, or transmission line impedance, NOT the choking

Re: [Elecraft] Balun Questions

: [Elecraft] Balun Questions I'll preface this by explaining that I'm a digital guy and I've lately decided I want to get a little better understanding of magnetics and RF...  Thus why I'm taking on making my own W3NQN band pass filters and I've also been interested in building a Balun... So I've looked

Re: [Elecraft] Balun Questions

On Fri, 23 Jul 2010 06:34:54 -0400, Tom W8JI wrote: The 100 ohms is the differential impedance, or transmission line impedance Tom is the balun expert around here, but he isn't telling you everything he knows, so I'll float a simple 4:1 balun design that should work quite well up to moderate

Re: [Elecraft] Balun Questions

This sounds really similar to a lot of plans that I've seen... One other piece that I've noticed on many of these that no one seems to ever mention is that the two 1:1's are usually wound in opposite directions on each half of the core... I'm assuming this helps to reduce the coupling between the

Re: [Elecraft] Balun Questions

This sounds really similar to a lot of plans that I've seen... One other piece that I've noticed on many of these that no one seems to ever mention is that the two 1:1's are usually wound in opposite directions on each half of the core... I'm assuming this helps to reduce the coupling between

Re: [Elecraft] Balun Questions

Ok I was referring to a design that was using one core to make a 4:1... I think the caveat that was being used was that they felt they could do this and be safe enough with it still being a balun as long as the load was floating (but I'm not 100% sure thats really the case)... So is a multi

Re: [Elecraft] Balun Questions

I've heard a lot of really great things about balun designs products... And in looking at their 4:1 for dipoles and yagi's it looks like they are simply doing 2 1:1 baluns on a single core. Looks to me like they are even wrapped in the same direction and paralleled on one side then series on the

Re: [Elecraft] Balun Questions

Brett, Do you have an old link coupled tuner - like the Johnson Matchbox or a homebrew one with plug-in coils? If you do, hook it up backwards with a dummy load on the normal input side. You have just created a tunable artificial antenna - tune the Matchbox to produce whatever load impedance

Re: [Elecraft] Balun Questions

Ok I was referring to a design that was using one core to make a 4:1... I think the caveat that was being used was that they felt they could do this and be safe enough with it still being a balun as long as the load was floating (but I'm not 100% sure thats really the case)... I can 100%

Re: [Elecraft] Balun Questions

Interesting enough his high power one uses two cores and appears to be made the same as the budget one that is wound on one core... Seems like stacking them on top of one another is going to just couple them and hinder your isolation but maybe I'm wrong there

Re: [Elecraft] Balun Questions

I haven't taken, nor at the moment do I have, the time to analyze this, but I'll throw it out. http://home.earthlink.net/~christrask/Trask4to1Balun.pdf Wes N7WS --- On Fri, 7/23/10, Tom W8JI w...@w8ji.com wrote: Ok I was referring to a design that was using one core to make a 4:1...  I

Re: [Elecraft] Balun Questions

Would this work with any tuner? That is, can I take a regular unbalanced tuner and put a dummy load on the input and then use it to create an artificial mismatch for testing? 73, phil, K7PEH P.S. Loss issues would not be important for my thinking of doing this. On Jul 23, 2010, at 11:22

Re: [Elecraft] Balun Questions

of Elecraft engineering would give me confidence to try one. Willis 'Cookie' Cooke K5EWJ From: Brett Howard br...@livecomputers.com To: elecraft elecraft@mailman.qth.net Sent: Fri, July 23, 2010 3:53:42 AM Subject: [Elecraft] Balun Questions I'll preface

Re: [Elecraft] Balun Questions

Brett, The coupling between the toroids is not as much of a problem as the flux cancellation when an attempt to use one core - that just does not work right. 73, Don W3FPR Brett Howard wrote: Interesting enough his high power one uses two cores and appears to be made the same as the budget

Re: [Elecraft] Balun Questions

On Jul 23, 2010, at 12:41 PM, Brett Howard wrote: Just bought the last copy of this book that Amazon had in stock for 17.95 + 3.99 in shipping. Looks like it will be a very nice reference to have on the shelf... Understanding, Building and Using Baluns and Ununs by the late Jerry Sevick,

Re: [Elecraft] Balun Questions

Interesting enough his high power one uses two cores and appears to be made the same as the budget one that is wound on one core... Seems like stacking them on top of one another is going to just couple them and hinder your isolation but maybe I'm wrong there Hi Bret, With two toroids

Re: [Elecraft] Balun Questions

1:1 baluns are dead easy to make: simply wind a few turns of the antenna end of your coax feeder around a suitable toroid core before connecting it to your balanced antenna. I use the FT241 cores from Amidon Associates, the k type for 160-40m bands or 61 mix for the higher HF bands. I can easily