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HF6V Tuning stub coax type


Andrew KD5RKO
 

Got an older HF6V for a great price minus the tuning stub. Don't really want to pay the $85 for the DX Engineering replacement part. Ebay vendor MPD Digital quoted me $48.90 plus shipping for one made with our 75 ohm variant of the Times LMR-400 with ring terminals.

So I'd like to try just making one myself. What I don't have is RG-11. I do have some other 75 ohm stuff on hand. So my question is how critical is the cable type at only 100W power and how much difference in cable length will it make? I do have a nanovna for testing. Should I be making it resonant at a certain frequency? 

Thanks

Andrew Harmon - KD5RKO


David KW4DH
 

It has to be cut for 20M.

David
KW4DH

On 8/19/2020 12:52 PM, Andrew KD5RKO wrote:
Got an older HF6V for a great price minus the tuning stub. Don't really want to pay the $85 for the DX Engineering replacement part. Ebay vendor MPD Digital quoted me $48.90 plus shipping for one made with our 75 ohm variant of the Times LMR-400 with ring terminals.

So I'd like to try just making one myself. What I don't have is RG-11. I do have some other 75 ohm stuff on hand. So my question is how critical is the cable type at only 100W power and how much difference in cable length will it make? I do have a nanovna for testing. Should I be making it resonant at a certain frequency? 

Thanks

Andrew Harmon - KD5RKO
-- 
"A president just can't make much showing against congress. 
They lay awake nights, thinking up things to be against the president on." 
~ Will Rogers


Ron Notarius W3WN
 

The Wireman has them for $44... gone up a little since the last time I had to replace one.

They should be cut for 20 meters.  If you are using an RG-11 type 75 ohm coax, the length is 11 feet 4 inches for a solid dielectric, 13 feet 6 inches for a foam type. Since you don't have RG-11, you may have to experiment a little bit, but I suspect that the length won't be substantially different, depending on what you're using, of course.

73, ron w3wn


-----Original Message-----
From: David KW4DH <collinsuser@...>
To: Butternut <Butternut@groups.io>
Sent: Wed, Aug 19, 2020 1:05 pm
Subject: Re: [butternut] HF6V Tuning stub coax type

It has to be cut for 20M.

David
KW4DH

On 8/19/2020 12:52 PM, Andrew KD5RKO wrote:
Got an older HF6V for a great price minus the tuning stub. Don't really want to pay the $85 for the DX Engineering replacement part. Ebay vendor MPD Digital quoted me $48.90 plus shipping for one made with our 75 ohm variant of the Times LMR-400 with ring terminals.

So I'd like to try just making one myself. What I don't have is RG-11. I do have some other 75 ohm stuff on hand. So my question is how critical is the cable type at only 100W power and how much difference in cable length will it make? I do have a nanovna for testing. Should I be making it resonant at a certain frequency? 

Thanks

Andrew Harmon - KD5RKO
-- 
"A president just can't make much showing against congress. 
They lay awake nights, thinking up things to be against the president on." 
~ Will Rogers


Peter VA3PET
 

I bought RG-11 from dx engineering and made my own 1/4 wave 20m tuning  stub. The amount of coax you'll need varies with its velocity factor.

I used my mfj-259 to create my stub but you can use the published vf or you could probably also use your nanovna to create the proper stub length for the 75ohm coax you choose.

73

Pete va3pet va3hr


From: Butternut@groups.io <Butternut@groups.io> on behalf of Ron Notarius W3WN via groups.io <wn3vaw@...>
Sent: Wednesday, August 19, 2020 1:23:42 PM
To: Butternut@groups.io <Butternut@groups.io>
Subject: Re: [butternut] HF6V Tuning stub coax type
 
The Wireman has them for $44... gone up a little since the last time I had to replace one.

They should be cut for 20 meters.  If you are using an RG-11 type 75 ohm coax, the length is 11 feet 4 inches for a solid dielectric, 13 feet 6 inches for a foam type. Since you don't have RG-11, you may have to experiment a little bit, but I suspect that the length won't be substantially different, depending on what you're using, of course.

73, ron w3wn


-----Original Message-----
From: David KW4DH <collinsuser@...>
To: Butternut <Butternut@groups.io>
Sent: Wed, Aug 19, 2020 1:05 pm
Subject: Re: [butternut] HF6V Tuning stub coax type

It has to be cut for 20M.

David
KW4DH

On 8/19/2020 12:52 PM, Andrew KD5RKO wrote:
Got an older HF6V for a great price minus the tuning stub. Don't really want to pay the $85 for the DX Engineering replacement part. Ebay vendor MPD Digital quoted me $48.90 plus shipping for one made with our 75 ohm variant of the Times LMR-400 with ring terminals.

So I'd like to try just making one myself. What I don't have is RG-11. I do have some other 75 ohm stuff on hand. So my question is how critical is the cable type at only 100W power and how much difference in cable length will it make? I do have a nanovna for testing. Should I be making it resonant at a certain frequency? 

Thanks

Andrew Harmon - KD5RKO
-- 
"A president just can't make much showing against congress. 
They lay awake nights, thinking up things to be against the president on." 
~ Will Rogers


Andrew KD5RKO
 

Thanks for the info everyone. I may just order some RG-11 and go that route if I can't dig any up locally. Now I just have to wait for some free time to mess with it!

Andrew KD5RKO


Nolan - KI5IO
 

Andrew,

Have you reviewed the files on this reflector about the tuning stub?

Here is a link to a couple:   https://groups.io/g/Butternut/files/75%20Ohm%20Matching%20Section%20Detail
--

73  -  ki5io
Nolan Kienitz
Plano, TX


Andrew KD5RKO
 

I have. They are very helpful. Just didn't have any RG-11 to work with and if anyone had used other grades of cable successfully. Thanks!


On Thu, Aug 20, 2020, 6:26 AM Nolan - KI5IO <ki5io@...> wrote:
Andrew,

Have you reviewed the files on this reflector about the tuning stub?

Here is a link to a couple:   https://groups.io/g/Butternut/files/75%20Ohm%20Matching%20Section%20Detail
--

73  -  ki5io
Nolan Kienitz
Plano, TX


--
Andrew - KD5RKO