It is currently Mon Oct 18, 2021 12:33 am

Click the link below to visit the site sponsor

The Ham Radio Shop




Post new topic Reply to topic  [ 8 posts ] 
 big loop resistance 
Novice Member

Joined: Tue Aug 12, 2014 4:56 pm
Posts: 28
Location: Botolan, Zambales, Philippines
Feedback: 1 (100%)
Reply with quote
Post big loop resistance
I live in the Philippines and have a massive garden. I put up a large loop aerial using both sides of D10 field telephone cable. Question is when I measure the DC resistance its 11.5 ohms. will this have an effect on the performance ? perhaps I should switch to copper wire.

_________________
Rob H G8MFV


Mon Sep 21, 2020 1:36 pm
Profile Send private message

 big loop resistance 
Advanced Member
User avatar

Joined: Wed Oct 30, 2013 2:47 pm
Posts: 2719
Location: Llanwrtyd Wells
Feedback: 33 (100%)
Reply with quote
Post Re: big loop resistance
RX or TX antenna?, measured with a cheesy meter or a megger?

Short answer, as a RX I doubt it, as a TX unless you are going to put Italian CB power through it I also doubt it.

_________________
Laugh along with the common people
Laugh along, even though they're laughing at you


Mon Sep 21, 2020 1:47 pm
Profile Send private message WWW

 big loop resistance 
Novice Member

Joined: Tue Aug 12, 2014 4:56 pm
Posts: 28
Location: Botolan, Zambales, Philippines
Feedback: 1 (100%)
Reply with quote
Post Re: big loop resistance
Its both TX and RX. measured with a Fluke 179 which had professional calibration. its 334 meters long.

_________________
Rob H G8MFV


Mon Sep 21, 2020 1:54 pm
Profile Send private message

 big loop resistance 
Advanced Member
User avatar

Joined: Wed Oct 30, 2013 2:47 pm
Posts: 2719
Location: Llanwrtyd Wells
Feedback: 33 (100%)
Reply with quote
Post Re: big loop resistance
G8MFV wrote:
Its both TX and RX. measured with a Fluke 179 which had professional calibration. its 334 meters long.


Radio uses high voltages, so I'd test it with some :)

as an aside, I loaded up a stretch of barb wire fencing, maybe 100m, for 80m and it worked OK

_________________
Laugh along with the common people
Laugh along, even though they're laughing at you


Mon Sep 21, 2020 1:56 pm
Profile Send private message WWW

 big loop resistance 
Advanced Member
User avatar

Joined: Mon Nov 11, 2013 10:41 pm
Posts: 1572
Location: Walsall IO82XN
Feedback: 5 (100%)
Reply with quote
Post Re: big loop resistance
G8MFV wrote:
I live in the Philippines and have a massive garden. I put up a large loop aerial using both sides of D10 field telephone cable. Question is when I measure the DC resistance its 11.5 ohms. will this have an effect on the performance ? perhaps I should switch to copper wire.


The DC resistance is irrelevant unless you intend to operate on ultra low frequencies. Anywhere else I.E. above a few tens of kilohertz the skin effect will prevail, and the current will be flowing along the surface of the wire, not through the core of it.

If this is the only wire you have to work with, and you have a good supply of it, run a second or third wire/s in parallel with the first, that way you will have an increased surface area for the current to flow over and as a result the losses will be lower.

If possible, space the parallel conductors slightly apart, that way it will help to reduce the proximity effect which will otherwise rob you of a little bit, though not too much, of your power.

Hope that helps!

73, Mark...

_________________
G-QRP * LIDS * FISTS * SKCC
https://www.brasspounder.net


Tue Sep 22, 2020 7:48 pm
Profile Send private message WWW

 big loop resistance 
Novice Member

Joined: Tue Aug 12, 2014 4:56 pm
Posts: 28
Location: Botolan, Zambales, Philippines
Feedback: 1 (100%)
Reply with quote
Post Re: big loop resistance
unfortunately the D10 comes as a twisted pair, and it's the very devil to separate on the length I have, so I have used it as it comes as a twisted pair. I don't think copper would stand the strain over the unsupported lengths I have to contend with.

_________________
Rob H G8MFV


Tue Sep 22, 2020 8:11 pm
Profile Send private message

 big loop resistance 
Advanced Member
User avatar

Joined: Mon Nov 11, 2013 10:41 pm
Posts: 1572
Location: Walsall IO82XN
Feedback: 5 (100%)
Reply with quote
Post Re: big loop resistance
G8MFV wrote:
unfortunately the D10 comes as a twisted pair, and it's the very devil to separate on the length I have, so I have used it as it comes as a twisted pair. I don't think copper would stand the strain over the unsupported lengths I have to contend with.


Don't worry about pulling the existing ones apart, I was just thinking if you ran a second twisted pair say, along side the first.

As I said though, it's only a small different, it's just me being overly keen! :D

73, Mark...

_________________
G-QRP * LIDS * FISTS * SKCC
https://www.brasspounder.net


Tue Sep 22, 2020 8:22 pm
Profile Send private message WWW

 big loop resistance 
Contributor 2020
User avatar

Joined: Sat Jun 18, 2011 4:15 pm
Posts: 15389
Location: io65ga, Donegal
Feedback: 9 (100%)
Reply with quote
Post Re: big loop resistance
As it stands more than half of the total number of strands are copper so i cant see changing to 100% all copper strands making much difference.

_________________
Even duct tape can't fix stupid, but it can muffle the sound.


Tue Sep 22, 2020 10:04 pm
Profile Send private message
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 


Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
cron
Powered by phpBB © phpBB Group.
Designed by Vjacheslav Trushkin for Free Forums/DivisionCore.