Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: 75 ohm RG59 for SWL feedline?  (Read 17874 times)
VE3KNT
Member

Posts: 10


WWW

Ignore
« on: October 06, 2013, 03:56:42 PM »

I just bought myself a Realistic DX-160 and want to sit it by the couch (probably) for some couch SWLing.  and because I'm in a apartment, I want the antenna in one of the windows, or maybe on the balcony if i can figure where to put it around my HF and VHF ham antennas in a very tight space.

I have a lot of Belkin RG59 75 ohm coax here, basically "new" (it was from a construction site where the security camera installer messed up and cut it too short, had to take it right back out and had to rewire all the CCTV cams...)

So I'm thinking it could make decent feed line for my new old shortwave.  I'm planning on adding a SO-239  to the radio for easier hook ups, then perhaps a PL259 to F-connector adapter and use cheaper F connectors on the RG59.. the run would be about 25 feet, maybe 30 depending on what furniture I go around..

So my question is; good idea, bad, idea? and I plan on making a loop antenna of sorts..  wood cross with a a few laps of wire around the posts..
Logged
KB4QAA
Member

Posts: 2414




Ignore
« Reply #1 on: October 06, 2013, 04:17:05 PM »

Impedance is not critical for listening.  Use what you have.
Logged
AA4PB
Member

Posts: 12899




Ignore
« Reply #2 on: October 06, 2013, 04:25:04 PM »

You can get RG59 size adapters for the PL-259 connector (matching plug for the SO-239) so you don't have to use F connectors and adapters.
Logged
VE3KNT
Member

Posts: 10


WWW

Ignore
« Reply #3 on: October 06, 2013, 05:06:15 PM »

You can get RG59 size adapters for the PL-259 connector (matching plug for the SO-239) so you don't have to use F connectors and adapters.

I know, I just wanted the SO239 so I can connect to to a HF antenna if I want to some time, and use F on RG59 just because it's easier to work with and really cheap  (ie: I hate soldering pl259's  Shocked )
Logged
WB6BYU
Member

Posts: 13343




Ignore
« Reply #4 on: October 07, 2013, 09:34:22 AM »

I don't know if they make PL-259 to F adaptors, but I know you can get
F to BNC and BNC to PL-259 if you don't want to make your own.  (Actually,
sticking a type-F jack in the back of a PL-259 to build your own adaptor
shouldn't be too difficult.)

RG-59 should work fine for SWR - it works for ham use as well in many cases.
Logged
WA8ZTZ
Member

Posts: 50




Ignore
« Reply #5 on: October 08, 2013, 01:14:27 PM »

I don't know if they make PL-259 to F adaptors

Radio Shack  278-258.
Logged
SWL2002
Member

Posts: 347




Ignore
« Reply #6 on: October 10, 2013, 03:33:20 AM »

You can get crimp on BNC connectors instead of F connectors if the coax you have does not already have F connectors on it.  This eliminates the F to BNC adapter.  You'll need the tool also, but it works for both F and BNC as well as RCA crimp ons.

I use these: http://www.amazon.com/Ideal-89-047-RG-59-Compression-Connector/dp/B001TJ160O/ref=sr_1_10?ie=UTF8&qid=1381401027&sr=8-10&keywords=BNC+RG59 

You can usually get smaller quantities from Lowes here in the USA and I am sure other places.  I use the RG6 version.

Logged
AA4HA
Member

Posts: 1493




Ignore
« Reply #7 on: October 10, 2013, 12:44:21 PM »

Mix-matching 50 ohm connectors on 75 ohm cable usually works. You will notice that the thickness of the center pin, the thickness of the center pin insulation (dielectric) and the shield (braid or foil or braid and foil) will be different. That is what really makes the difference between 50 and 75 ohms, the ratio of those spacings and sizes.

There are inter-species adapters/ connectors (75 ohm Type-F to 50 ohm BNC) and unless you are doing some critical work where those impedances matter (with transmitters) you will never notice the difference. You can even terminate 75 ohm cable with 50 ohm connectors. Just be aware that there are some size differences.

For receivers like a scanner or a general purpose SWL radio I would use what I have on hand. Left over 75 ohm coax is too good of a deal to pass up. Just be aware (from a theoretical standpoint) that there is an impedance "bump".
Logged

Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
K7KBN
Member

Posts: 2814




Ignore
« Reply #8 on: October 15, 2013, 11:44:13 AM »

Don't even bother with coax.  Attach a long piece of copper wire to the screw terminal on the back of the radio.  Run the other end out a window and keep it as long and as high as you can.
Logged

73
Pat K7KBN
CWO4 USNR Ret.
RENTON481
Member

Posts: 67




Ignore
« Reply #9 on: October 18, 2013, 09:29:25 AM »

I used to run a V-beam into my DX-160 using coax.  The coax had a typical coax connector on the end.  On the radio side I had a coax 'female' counterpart (don't remember the part number, poss. SO-239), to which I soldered two short stubs of hookup wire, to connect it the DX-160's screw in terminals. The coax was probably 40 feet between the radio and the actual antenna.

The antenna / radio combination worked well.  I live in a low signal area, so I didn't have to deal with many overload images.

For an old analog SW radio the DX-160 has good sensitivity and good selectivity.  Works especially well on the MW band.

But it does overload easy, if you're in a high-signal area, so a long antenna might give you some ghost images below the major SW broadcast bands.  The overloading can be overcome with an antenna tuner.  You might not have that much of a problem with it with the loop antenna you plan on using.
Logged
KD7RDZI2
Member

Posts: 73




Ignore
« Reply #10 on: October 30, 2013, 03:22:14 PM »

I would consider the impedance of the antenna input. If there are terminals they might be at 300ohm or higher. For listening mismatch is less critical but if the antenna input is 300 or 450 ohm I would use ladder line instead of coax and as an antenna a random lenght dipole without any balun. Ladder line is not a compromise: it is simply more efficient than any coax.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!