Thanks for all the replies, I am not shopping but have some RG189 on a reel
with connectors in my garage and looking at how I may make use of it.
I may use it for VHF and UHF applications on my tower in the future.
Thanks again.
tnx es 73
Bill wa4lav
________________________________________
From: Shon Edwards [sre.1966@gmail.com]
Sent: Monday, January 02, 2017 10:17 AM
To: Fuqua, Bill L
Cc: Amplifier Reflector
Subject: Re: [Amps] Coax specs
Hi Bill and the list.
I just want to let you know I might ramble a little, but here are some of my
thoughts. I want to mention first where you can find some cable on the
Internet; the results of a little test I did using this type of large cable
(unfortunately mine is bigger even than this); and a word about velocity
factor. I hope this isn't going to bore too many of you too much. I am just
sort of an amateur myself when it comes to radios and radio parts.
I do all my coax shopping over the Internet at a place called "RF Parts" in
Southern California, if I remember correctly. They do have a $25.00 minimum
order, but that isn't usually so difficult once you figure out your cable
length, connectors, etc. I just did a search for "rg-189 7/8" 50 ohm coax"
once I entered the site and got the following;
https://www.rfparts.com/catalogsearch/result/?q=rg-189+7%2F8%22+50+ohm+coax I
then did a search for "lmr 900 50 ohm coax" and got quite a few pages of hits.
It may even be the same list of my last last search. Not sure. When I did the
second search, I had to click on "p. 4" on my machine at the bottom of the
screen to get to the right area which display the higher end LMR cables. I
clicked on the LMR 900 DB (direct burial, or weather proof) at:
https://www.rfparts.com/lmr900db.html. You have to order this quite a bit in
advance, but I'd rather do it over any other non-weather protected coax.
I had a project where I was using frequencies around 33 CM and needed a run
from my 900 MHz yagi antenna to the radio. At such high frequencies, big cable
like this is extremely important. I hooked the yagi up to my radio using a 1
M run of LMR 400. It sounded as clear as a bell. I had people located 50
miles away from me, where the repeater is. No problem. They said I didn't
even have a trace of "popcorn" (a type of static unique to those higher
frequencies).
That was great, but I didn't want to leave the yagi on the entertainment center
forever, so I take it out through a "pass through" through the window and get
it out to the antenna. I tried to use only DB because I would rather it have
all the protection it can get over the years against the elements. LMR 900 DB
was the best type of coax (but most expensive). I used N connectors, so as not
to get as much loss (ni Europe VHF and up use N connectors). Anyway, (sorry to
make a short response long -- just wanted to write it all out in case anyone
might benefit from what I've done (or haven't done) right. I connected a LMR
400 run-off wire from the LMR 900 to the radio to be able to fit it through the
pass-through, as well as to make the coax malleable enough by the time it got
to the radio that it wouldn't break the connector off every time I moved the
radio. And with all of these even STILL, I had some popcorn My run was only
around 8 M of cable and still I was losing a l
ot of signal. .
Using the VF (velocity factor), calculate the proper length of the cable. This
is explained in the Extra ARRL manual, about 2/3 of the way through the book.
Whenever I've done this, I always get 1:1 SWR or extremely close, At high
frequencies, it makes it even more critical. You should check with someone who
knows about the subject, if necessary.
I'll show you a piece of my bill here, which I paid to RF Parts. Note
especially the "large" N connectors to fit onto the large LMR 900 cable.
They're $68 each to buy them and I think it looks like it was $25 per for
labor. Not having worked with cable that big before, I left it to them to work
out. Then there was the cable, which was around a little over $18/meter. Wow!
Shipping's another 18 and there you have it: $350 for an 8 M legnth of coax!
Item Sku Qty Subtotal
LMR900DB 0.870 Dia, Low Loss Coax, Direct Buriel LMR900DB 24
$142.80
EZ900NMC-2 Type-N Male Clamp Connector, LMR900DB EZ900NMC-2 2
$135.90
LABOR-XLARGE LABOR-XLARGE 2 $50.00
Subtotal $328.70
Shipping & Handling $18.00
Grand Total (Excl.Tax) $346.70
Tax $0.00
Grand Total (Incl.Tax) $346.70
Shon R. Edwards, MA, AG (Czech Republic)
Amateur call: K6QT
1039 N 2575 W
Layton, UT, 84041-7709
USA
Home phone: (801) 444-3445<tel:(801)%20444-3445>
E-mail: sre.1966@gmail.com<mailto:sre.1966@gmail.com>
or
Shon Edwards
715 Strawberry Creek Private Rd.
Bedford, WY 83112
Cell: (307) 248-2104<tel:(307)%20248-2104>
On Sun, Jan 1, 2017 at 1:48 AM, Jim Brown
<jim@audiosystemsgroup.com<mailto:jim@audiosystemsgroup.com>> wrote:
Hi Bill,
Remember that RG numbers are no longer specs for cable, merely generic
descriptors. Remember also that below UHF, attenuation is all copper loss, so
if you can get physical dimensions and construction details, you can get pretty
close to its loss by comparing to another cable with the same dimensions and
construction.
Google found this on the first try. Center is solid copper, 0.25-in, shield is
double silver-covered copper. Dielectric is 0.632-in.
http://www.awcwire.com/productspec.aspx?id=rg189-coaxial-cable
http://catalog.standard-wire.com/Asset/RG-Attenuation.pdf lists attenuation
for a bunch of RG numbers, and I saw a note in my searches that 189 has been
replaced by 389. RG389 is listed here as 0.8 dB at 100 MHz.
73, Jim K9YC
On Sat,12/31/2016 10:55 PM, Fuqua, Bill L wrote:
Does anyone have the attenuation vs frequency specs for RG189 cable?
I can't seem to find it anywhere. It is 7/8" 50 Ohms and that is about all I
have found.
73
Bill wa4lav
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