Butternut Hf6v 75 Ohm Feed Coaxial Cable Length

Has anyone ordered a 75 ohm tuning stub from Wireman lately? If so I would like your comments as to the build quality. I need to replace the original stub on my, at least, 15 year old HF9V. Other than buying the cable or stub itself from DX engineering, are there any other vendors for the stub out there?

Thanks, Jim W6yxy

Jim,

DX & Wireman are the two known vendors that make them. Both are good quality. Of course, you can make one yourself if you have the coax. It's easy enough.

Scott AC8DE

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From: Butternut-antennas@... [mailto:Butternut-antennas@...]
Sent: Wednesday, November 01, 2017 3:55 PM
To: Butternut-antennas@...
Subject: [Butternut-antennas] 75 ohm tuning stub from Wireman

Thanks, Jim W6yxy

Thanks Scott. Wish there was a local vendor for bulk RG11 as I would make my own. I made one up a couple of years ago from cable that I got from DX engineering. Used my MFJ-259B to get the stub tuned to 20 meters. Seemed to work fine until very recently I noticed that I was getting erratic SWR readings. Was starting to think I had a bad connection somewhere in the antenna. I connected the MFJ-259 to the end of the stub to take some SWR data and it became apparent that the bad connection was at the PL-259 that I had installed on the RG11. When I did a closer inspection of the connector I noticed that there was a lot of corrosion in the area of the shield. I've been licensed for 50 years and have put many connectors on cables over that time and never seen one that corroded despite using tape and coax seal. Thought I would just cut the connector off and install a new one onto clean coax. When I cut the covering to expose the shield I noticed the shield had turned black and likely would not hold any solder. I decided to abandon that cable and go back to the one that came with the antenna originally. Its not in great shape so I've decided to replace it sooner rather than later. I will probably continue to look for some RG11 locally over the next week to build my own but if I don't find anything I will likely order from Wireman.

73 Jim

Tom Parkinson

When you see the copper shield in coax turned to black, that's a strong indication that water ( moisture ) has entered the coax somewhere. The braid will suck up water like a paper towel. A real close inspection may show just a slight cut somewhere in the jacket. That's all it takes. Or it may have migrated through a connector that is not 100% weatherproofed. Another indication that the coax has water is an unexpected rise in SWR.

73,

TOM, KB8UUZ

Sent from my Samsung Galaxy smartphone.

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-------- Original message --------

From: "jkeller@... [Butternut-antennas]" <Butternut-antennas@...>

Date: 11/2/17 23:08 (GMT-05:00)

To: Butternut-antennas@...

Subject: RE: [Butternut-antennas] 75 ohm tuning stub from Wireman

73 Jim

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From: Butternut-antennas@... [mailto:Butternut-antennas@...]
Sent: Thursday, November 2, 2017 10:08 PM
To: Butternut-antennas@...
Subject: RE: [Butternut-antennas] 75 ohm tuning stub from Wireman

73 Jim

So I decided to buy the stub from Wireman. Received it today and the build quality looks great. My first thought was that rather than putting on lugs they installed a UHF female connector. I should have questioned it before I purchased as that is how the description on their website reads. The description on the invoice that came with it indicates lugs.

Couple of questions.

Since it doesn't have lugs should I make a short 52 ohm cable up with lugs to attach between the stub and antenna?

When I put the stub on my MFJ-259B with a dummy load on the other end, I see resonance or lowest SWR at 29 MHz. At 14 MHz the SWR is about 2:1 across all of 20 meters. Is this normal? The stub is 11.5 feet of RG11.

Thanks, Jim W6yxy

Black shield means either water entrance, or a hard lightning strike. Most metals typically oxidize to black in low-oxygen conditions, except silver, which always goes to black. But when you see the braid has left a significant pattern in both insulators (inner and jacket), it means a lightning strike and the coax should be discarded or given to a CBer. ;)

Jim N6OTQ

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On Thu, Nov 2, 2017 at 10:34 PM, kb8uuz kb8uuz@... [Butternut-antennas] <Butternut-antennas@...> wrote:

When you see the copper shield in coax turned to black, that's a strong indication that water ( moisture ) has entered the coax somewhere. The braid will suck up water like a paper towel. A real close inspection may show just a slight cut somewhere in the jacket. That's all it takes. Or it may have migrated through a connector that is not 100% weatherproofed. Another indication that the coax has water is an unexpected rise in SWR.

73,

TOM, KB8UUZ

Hello, Jim,

No, that is not normal.

The stub should show resonance on your analyzer at your normal 20M operating frequency. I guess you could extend the one you have, but you need 75 ohm RG-11 to do that.

I just made up my own new stub using RG-11 from DX Engineering. I installed a PL259 on one end and trimmed the length to resonate at 14.15 MHz using my MFJ 259. I started with 18 feet (too long) and ended up with about 15 feet, including the pigtail and the lugs I soldered on.

Not a perfect match, but very near 1:1 SWR on 20M.

If you don't want to install the PL259, you could order an RG-11 cable about 18 ft with PL259s installed, then cut off one end and trim.

Regards

Richard, K1RS

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On Nov 8, 2017, at 4:04 PM, jkeller@... [Butternut-antennas] <Butternut-antennas@...> wrote:

So I decided to buy the stub from Wireman. Received it today and the build quality looks great. My first thought was that rather than putting on lugs they installed a UHF female connector. I should have questioned it before I purchased as that is how the description on their website reads. The description on the invoice that came with it indicates lugs.

Couple of questions.

Since it doesn't have lugs should I make a short 52 ohm cable up with lugs to attach between the stub and antenna?

When I put the stub on my MFJ-259B with a dummy load on the other end, I see resonance or lowest SWR at 29 MHz. At 14 MHz the SWR is about 2:1 across all of 20 meters. Is this normal? The stub is 11.5 feet of RG11.

Thanks, Jim W6yxy

quarterwave transformer for 20 is a halfwave for 10

halfwave lines always "mirrors" what is on the other end ... so the dummy is like it was connected direct to analyzer (on 10m)

...

on 20 it is a quarterwave transformer

with its impedance of 75 ohms it transforms 50 ohms to 100 ohms (and that is why you measure 1:2 swr) ... OR THE OTHER WAY AROUND ... (see below)

...

whan connected to a butternut it is same thing (but other way around) ... on 20 the butternut is longer as a quarterwave ... and so it has higher impedance (roughly 100 ohms) ... that is then transformed down to a perfect match (50 ohms) behind the quarterwave transformer

....

yes it is okay to add a SHORT jumper just to have some lugs for connecting the stub

too long would influence swr too much ... but a short jumper should be okay ... maybe a slight retuning needed but i am not sure

dg9bfc sigi

Am 09.11.2017 um 00:04 schrieb jkeller@... [Butternut-antennas]:

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So I decided to buy the stub from Wireman. Received it today and the build quality looks great. My first thought was that rather than putting on lugs they installed a UHF female connector. I should have questioned it before I purchased as that is how the description on their website reads. The description on the invoice that came with it indicates lugs.

Couple of questions.

Since it doesn't have lugs should I make a short 52 ohm cable up with lugs to attach between the stub and antenna?

When I put the stub on my MFJ-259B with a dummy load on the other end, I see resonance or lowest SWR at 29 MHz. At 14 MHz the SWR is about 2:1 across all of 20 meters. Is this normal? The stub is 11.5 feet of RG11.

Thanks, Jim W6yxy

Richard ... YOU ARE WRONG!! THAT IS NORMAL WHAT HE MEASURES (excuse for shouting)

he said he had a dummy on one end ... and that will show perfect 1:1 on the HALFWAVE resonance

and will show 1:2 at quarterwave resonance ...

....

other thing is if you make a short at the far end and connect the dummy load to analyzer with a t-connector

then the short will be transformed to an open at the analyzer end on quarterwave resonance and you measure a perfect match cause you then only see the dummy with the analyzer

halfwave resonance will then show infinite swr (the short is transformed to the analyzer end and you measure the short with the analyzer like it was made direct at the analyzers connector)

so ... there are different setups to measure a stub ... but only one is really accurate (with the short at far end and with t-connector and dummy on analyzer end)

.....

for testing you can connect a 100 ohms resistor at the far end ... and the analyzer should show 1:1 on 20m (100 transformed down to 50 with a quarterwave transformer of 75 ohms)

....
let me do an educated guess ... cause you measured wrong you have measured resonance of the jacket (15 feet are about a quarterwave on 20m) ... but you have to have resonance on the coax inner!!!

ever heard of velocity factor?!?

around 11-12 feet is ok (depending on cable type) ... but 15 feet is way to long

dg9bfc sigi

ps explain us how you made your test setup ... and we find your fault

Am 09.11.2017 um 02:06 schrieb Richard Schmidt kuesrks@... [Butternut-antennas]:

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Hello, Jim,

No, that is not normal.

The stub should show resonance on your analyzer at your normal 20M operating frequency. I guess you could extend the one you have, but you need 75 ohm RG-11 to do that.

I just made up my own new stub using RG-11 from DX Engineering. I installed a PL259 on one end and trimmed the length to resonate at 14.15 MHz using my MFJ 259. I started with 18 feet (too long) and ended up with about 15 feet, including the pigtail and the lugs I soldered on.

Not a perfect match, but very near 1:1 SWR on 20M.

If you don't want to install the PL259, you could order an RG-11 cable about 18 ft with PL259s installed, then cut off one end and trim.

Regards

Richard, K1RS

So I decided to buy the stub from Wireman. Received it today and the build quality looks great. My first thought was that rather than putting on lugs they installed a UHF female connector. I should have questioned it before I purchased as that is how the description on their website reads. The description on the invoice that came with it indicates lugs.

Couple of questions.

Since it doesn't have lugs should I make a short 52 ohm cable up with lugs to attach between the stub and antenna?

When I put the stub on my MFJ-259B with a dummy load on the other end, I see resonance or lowest SWR at 29 MHz. At 14 MHz the SWR is about 2:1 across all of 20 meters. Is this normal? The stub is 11.5 feet of RG11.

Thanks, Jim W6yxy

There is no "fault".

The coax I used has a higher velocity factor, therefore is longer for 1/4 wave at the operating frequency. As most know, solid and foam dielectric coaxes have different velocity factors. The only way to know the velocity factor for certain is to trim the coax to the correct length using the analyzer. The MFJ manual clearly explains how to do this. No T's, resistors or dummy loads are required to get it right.

If Jim's coax stub resonates at 29 MHz with a dummy load attached, it's probably too short and will show up on a 1/4 wave open circuit test at about 14.5 MHz, and that is not right.

Many of the pre-made matching stubs are cut using a spec sheet or theoretical velocity factor and end up too short or too long. That's why many Butternuts have about 1.7-1.9 SWR on 20. Mine is now 1.1/1 works just fine.

Now, please go shout at someone else.

Richard K1RS

Richard ... YOU ARE WRONG!! THAT IS NORMAL WHAT HE MEASURES (excuse for shouting)

he said he had a dummy on one end ... and that will show perfect 1:1 on the HALFWAVE resonance

and will show 1:2 at quarterwave resonance ...

....

other thing is if you make a short at the far end and connect the dummy load to analyzer with a t-connector

then the short will be transformed to an open at the analyzer end on quarterwave resonance and you measure a perfect match cause you then only see the dummy with the analyzer

halfwave resonance will then show infinite swr (the short is transformed to the analyzer end and you measure the short with the analyzer like it was made direct at the analyzers connector)

so ... there are different setups to measure a stub ... but only one is really accurate (with the short at far end and with t-connector and dummy on analyzer end)

.....

for testing you can connect a 100 ohms resistor at the far end ... and the analyzer should show 1:1 on 20m (100 transformed down to 50 with a quarterwave transformer of 75 ohms)

....
let me do an educated guess ... cause you measured wrong you have measured resonance of the jacket (15 feet are about a quarterwave on 20m) ... but you have to have resonance on the coax inner!!!

ever heard of velocity factor?!?

around 11-12 feet is ok (depending on cable type) ... but 15 feet is way to long

dg9bfc sigi

ps explain us how you made your test setup ... and we find your fault

Am 09.11.2017 um 02:06 schrieb Richard Schmidt kuesrks@... [Butternut-antennas]:

Hello, Jim,

No, that is not normal.

The stub should show resonance on your analyzer at your normal 20M operating frequency. I guess you could extend the one you have, but you need 75 ohm RG-11 to do that.

I just made up my own new stub using RG-11 from DX Engineering. I installed a PL259 on one end and trimmed the length to resonate at 14.15 MHz using my MFJ 259. I started with 18 feet (too long) and ended up with about 15 feet, including the pigtail and the lugs I soldered on.

Not a perfect match, but very near 1:1 SWR on 20M.

If you don't want to install the PL259, you could order an RG-11 cable about 18 ft with PL259s installed, then cut off one end and trim.

Regards

Richard, K1RS

So I decided to buy the stub from Wireman. Received it today and the build quality looks great. My first thought was that rather than putting on lugs they installed a UHF female connector. I should have questioned it before I purchased as that is how the description on their website reads. The description on the invoice that came with it indicates lugs.

Couple of questions.

Since it doesn't have lugs should I make a short 52 ohm cable up with lugs to attach between the stub and antenna?

When I put the stub on my MFJ-259B with a dummy load on the other end, I see resonance or lowest SWR at 29 MHz. At 14 MHz the SWR is about 2:1 across all of 20 meters. Is this normal? The stub is 11.5 feet of RG11.

Thanks, Jim W6yxy

hmmm ... he wants to add a jumper to have solder lugs on the end ... that should give him the needed lenght for coming a bit down in frequency (if the stub really is resonating on 14.5)

... sorry i did not want to step on your toes ...

but you said something wrong to another ham who asked for help

he said ... i connected a dummy to the far end and i measured 1:2 at 14 megs (very broad so maybe the real resonance may be at 14.5?!?) ... and he measured 1:1 on 29 megs ... and asked if that is normal ... and that is normal .... (already explained)

with nothing but the stub connected you measure a "short" on the operating frequency when far end is left open ... what does the analyzer show with a short?? infinite swr?!?

most analyzers are more accurate when you use them around their design impedance and that is why i wrote "use a t-connector and a dummy and make a short at the far end" ... that way you measure a perfect 1:1 on design frequency

....

ok on the foam dielectric ... (but isnt 15 feet still a bit long?!?)

greetz

sigi dg9bfc

Am 09.11.2017 um 21:23 schrieb Richard Schmidt kuesrks@... [Butternut-antennas]:

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There is no "fault".

The coax I used has a higher velocity factor, therefore is longer for 1/4 wave at the operating frequency. As most know, solid and foam dielectric coaxes have different velocity factors. The only way to know the velocity factor for certain is to trim the coax to the correct length using the analyzer. The MFJ manual clearly explains how to do this. No T's, resistors or dummy loads are required to get it right.

If Jim's coax stub resonates at 29 MHz with a dummy load attached, it's probably too short and will show up on a 1/4 wave open circuit test at about 14.5 MHz, and that is not right.

Many of the pre-made matching stubs are cut using a spec sheet or theoretical velocity factor and end up too short or too long. That's why many Butternuts have about 1.7-1.9 SWR on 20. Mine is now 1.1/1 works just fine.

Now, please go shout at someone else.

Richard K1RS

Richard ... YOU ARE WRONG!! THAT IS NORMAL WHAT HE MEASURES (excuse for shouting)

he said he had a dummy on one end ... and that will show perfect 1:1 on the HALFWAVE resonance

and will show 1:2 at quarterwave resonance ...

....

other thing is if you make a short at the far end and connect the dummy load to analyzer with a t-connector

then the short will be transformed to an open at the analyzer end on quarterwave resonance and you measure a perfect match cause you then only see the dummy with the analyzer

halfwave resonance will then show infinite swr (the short is transformed to the analyzer end and you measure the short with the analyzer like it was made direct at the analyzers connector)

so ... there are different setups to measure a stub ... but only one is really accurate (with the short at far end and with t-connector and dummy on analyzer end)

.....

for testing you can connect a 100 ohms resistor at the far end ... and the analyzer should show 1:1 on 20m (100 transformed down to 50 with a quarterwave transformer of 75 ohms)

....
let me do an educated guess ... cause you measured wrong you have measured resonance of the jacket (15 feet are about a quarterwave on 20m) ... but you have to have resonance on the coax inner!!!

ever heard of velocity factor?!?

around 11-12 feet is ok (depending on cable type) ... but 15 feet is way to long

dg9bfc sigi

ps explain us how you made your test setup ... and we find your fault

Am 09.11.2017 um 02:06 schrieb Richard Schmidt kuesrks@... [Butternut-antennas]:

Hello, Jim,

No, that is not normal.

The stub should show resonance on your analyzer at your normal 20M operating frequency. I guess you could extend the one you have, but you need 75 ohm RG-11 to do that.

I just made up my own new stub using RG-11 from DX Engineering. I installed a PL259 on one end and trimmed the length to resonate at 14.15 MHz using my MFJ 259. I started with 18 feet (too long) and ended up with about 15 feet, including the pigtail and the lugs I soldered on.

Not a perfect match, but very near 1:1 SWR on 20M.

If you don't want to install the PL259, you could order an RG-11 cable about 18 ft with PL259s installed, then cut off one end and trim.

Regards

Richard, K1RS

So I decided to buy the stub from Wireman. Received it today and the build quality looks great. My first thought was that rather than putting on lugs they installed a UHF female connector. I should have questioned it before I purchased as that is how the description on their website reads. The description on the invoice that came with it indicates lugs.

Couple of questions.

Since it doesn't have lugs should I make a short 52 ohm cable up with lugs to attach between the stub and antenna?

When I put the stub on my MFJ-259B with a dummy load on the other end, I see resonance or lowest SWR at 29 MHz. At 14 MHz the SWR is about 2:1 across all of 20 meters. Is this normal? The stub is 11.5 feet of RG11.

Thanks, Jim W6yxy

Today I made up a very short piece of RG8X with a PL259 at one end and lugs at the other to attach the 75 ohm stub to the antenna. Just for grins I attached a 100 ohm resister to the lugs and measured the impedance on 20 meters. SWR was 1.1 across the band so I think I am good to install the stub to my HF-9V. Thanks to all for your comments.

73 Jim W6yxy

If you use THAT tuning stub, be aware of its power limitations -- it can't handle a full-on "full legal limit" signal.

Jim N6OTQ

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On Fri, Nov 10, 2017 at 5:19 PM, jkeller@... [Butternut-antennas] <Butternut-antennas@...> wrote:

Today I made up a very short piece of RG8X with a PL259 at one end and lugs at the other to attach the 75 ohm stub to the antenna. Just for grins I attached a 100 ohm resister to the lugs and measured the impedance on 20 meters. SWR was 1.1 across the band so I think I am good to install the stub to my HF-9V. Thanks to all for your comments.

73 Jim W6yxy

Thanks for the info Jim but I only run 100 watts max SSB and lately I've been running 30 watts with FT8 so I should be good.

Jim

I do have the 75 ohm stub from Wireman but I bought it a couple years ago. The build quality seems very good as it is has a nice molded covering at the antenna connection end which should keep the water out. I am going to put the antenna back up after replacing the bottom tubing bent from a tornado and I will then use the one I got from The Wireman. I will let you know how it works.

I was able to whip up a 75 ohm tuning stub pretty easily using my antenna analyzer. If I have the automatic tuner in line anyway (I use it all the time for 17M) do I actually need the tuning stub with a tuner?Somewhere I read that while necessary to achieve 50 ohms on 20, it may degrade other bands. It certainly works, as I have a 1.1 match on 20M without the tuner.

I have had pretty excellent results using my HF6V on every band except 160. The jury is out on 6M, but I've worked over a dozen states on that band as well.

So, my question is, do I really need the stub with a tuner? Is the insertion loss of the tuner worth it, if I'm getting under 1.5 SWR on the bands for which the antenna was designed?

Thanks very much de Art KD0GY

I have an HF6V I got free from a friend. It had been modded which I won't get into. When I finally took out the mods AND got the impedence matching coil from DXE which was missing it tuned up like a champ. It is 1-1 on 3.645 with a 2-1 bandwidth of about 50kc, 1-1 on most of 40, all of 30, all of 20, not bad on 17 but I use the tuner in the rig since the amp will not tune up there. 10, 12, and 15 I use the tuner on since I don't feel like taking it down to retune 10 and 15 at present. The original matching stub works great after I cleaned up the connector. I have 16 or so radials of random lengths stapled into the lawn. It gets me on the air from my small city lot.

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On Saturday, November 18, 2017 12:47 PM, "artielangston@... [Butternut-antennas]" wrote:

I have had pretty excellent results using my HF6V on every band except 160. The jury is out on 6M, but I've worked over a dozen states on that band as well.

So, my question is, do I really need the stub with a tuner? Is the insertion loss of the tuner worth it, if I'm getting under 1.5 SWR on the bands for which the antenna was designed?

Thanks very much de Art KD0GY

If you are using a tuner, no, you don't need the matching section. Of course, the entire idea of the Butternut was to not need a tuner. But truth be told, I'll bet the majority have tuner in their systems.

Scott AC8DE

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From: Butternut-antennas@... [mailto:Butternut-antennas@...]
Sent: Saturday, November 18, 2017 12:48 PM
To: Butternut-antennas@...
Subject: [Butternut-antennas] Re: 75 ohm tuning stub from Wireman

I was able to whip up a 75 ohm tuning stub pretty easily using my antenna analyzer. If I have the automatic tuner in line anyway (I use it all the time for 17M) do I actually need the tuning stub with a tuner? Somewhere I read that while necessary to achieve 50 ohms on 20, it may degrade other bands. It certainly works, as I have a 1.1 match on 20M without the tuner.

I have had pretty excellent results using my HF6V on every band except 160. The jury is out on 6M, but I've worked over a dozen states on that band as well.

So, my question is, do I really need the stub with a tuner? Is the insertion loss of the tuner worth it, if I'm getting under 1.5 SWR on the bands for which the antenna was designed?

Thanks very much de Art KD0GY

Art,

If tuners are the easy solution in the shack , why bother to tune the antenna itself with all those tricky tuning points?

Who cares ? There is the tuner !

Or do not buy Butternut and place a 30ft pole over radials instead, again, there is tuner saving us...

I prefer to get closest to 50ohm with as less losses as possible at feedpoint, and let feedline doing its job carrying RF from a 50ohm source to a 50 ohm load without further issues.....

Federico

ik3umt

hollowaykertiver1988.blogspot.com

Source: https://groups.io/g/Butternut/topic/75_ohm_tuning_stub_from/11169381?p=

Butternut Hf6v 75 Ohm Feed Coaxial Cable Length

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