Not to beat a dead horse or anything (I know we talk about this a lot)
but once I started using RG400 (I know 142 is popular, I like the
flexibility of the 400) on everything "interconnect" (which are all
short) and hardline to the antenna, I've had no coax induced noise.
Period.
I'm not saying this to promote my coax choices or to say my choices
are better than someone else's. but because I'm not sure I ever just
said it here. This recipe has really made life better -- in the end,
well worth the cost of the RG400. And a tip I've found for cost-
effective RG400 and RG142: Avionics. Avionics installations often have
to use "the good stuff". I've found it significantly cheaper from
aviation supply houses, or getting some throw-away pieces from
avionics shops.
73 DE N0MJS
On Aug 31, 2009, at 2:13 PM, <n...@myqrz.com> <n...@myqrz.com> wrote:
> Thanks for the correction Bob. I think it was still a little early
> for me
> when I typed that email.
>
> Corey N3FE
>
> On Mon, 31 Aug 2009 10:14:58 -0700, n...@no6b.com wrote:
> > At 8/31/2009 09:03, you wrote:
> >
> >
> >
> >>Good Morning/Afternoon Jim!
> >>
> >>Not sure about the Antenna, I know Randy's (HJC) is working great!
> Any
> >>type of double shielded coax/feedline anywhere in the system will
> cause
> >>problems. As the temp inside or outside changes it can cause the
> shield
> >>to rub together and make a lot of noise on the repeater. Even if
> it is
> >>used inside on the duplexers...
> >
> > This is incorrect. Silver-plated double-shielded coax is
> practically the
>
> > standard for duplex interconnects. Non silver-plated braided coax
> will
> > generate noise, whether it's double shielded or not, due to the
> eventual
> > oxidation of the copper & resulting poor intra-braid contact.
> >
> >> I had mentioned to the person you are referring to that I may be
> able
> >> to find some 1/2" hardline but he thought it may be to weighted
> for what
>
> >> he is doing...
> >
> > This would be a good choice for the duplexer-antenna feed, with
> RG-214
> > jumpers between the hardline & duplexer/antenna.
> >
> > Bob NO6B
> >
> >
> >>Corey N3FE
> >>
> >>On Mon, 31 Aug 2009 11:46:36 -0400, "Chuck Kelsey"
> >>wrote:
> >> > Sounds like maybe a bad antenna. Don't use the foil/braid cable
> >> > anywhere in
> >> >
> >> > a repeater system.
> >> >
> >> > Chuck
> >> > WB2EDV
> >> >
> >> >
> >> >
> >> > ----- Original Message -----
> >> > From: "ka2ajh"
> >> > To:
> >> > Sent: Monday, August 31, 2009 9:33 AM
> >> > Subject: [Repeater-Builder] Tram 1481 Dual Band UHF/VHF Antenna
> >> >
> >> >
> >> >> Hi Guys,
> >> >> We spent most of yesterday working on a UHF Mastr II Exec.
> Repeater,
> >> >> we
> >> >> are using a TRAM 1481 Dual Band Antenna on. This is the high
> gain 8.3
> >> >> dB
> >> >> VHF/11.7 UHF. The system uses UHF Repeater, VHF Simplex, and
> IRLP.
> The
> >> >> antenna works very poorly on UHF and much better on VHF. The
> SWR is
> >> >> about
> >> >>
> >> >> 3-1 on both frequencies. The antenna is not DC Ground and
> there is no
> >> >> shorted connectors. Lack of help prevented us from taking the
> antenna
> >> >> down
> >> >> and apart at this time. We ran tests by putting the antenna on a
> >> >> portable
> >> >>
> >> >> and working a fixed base and again the VHF pinned the meter
> and the
> >> >> UHF
> >> >> was weak, only a couple of S units better than the portable
> rubber
> >> >> duck.
> >> >> Has anyone had a similar problem. I understand that the
> antenna is a
> >> >> compromise and not as good as a single band folded dipole for
> example,
> >> >> but
> >> >> several of us have these and they work great except for this
> one. I
> am
> >> >> thinking there are enough Tram 1481 out there and someone may
> have
> had
> >> >> the
> >> >> same problem.
> >> >> Also there has been many posts about the LMR400 used in repeater
> >> >> service.
> >> >>
> >> >> It is my understanding that the foil type should NEVER be used
> between
> >> >> duplexers, from the TX, RX to the Duplexers, but I am not sure
> about
> >> >> between the duplexer and the antenna. Comments please!
> >> >> My friend has the LM400 on the repeater mentioned above and I
> know it
> >> >> is
> >> >> NOT the present problem as even on simplex the antenna
> performance on
> >> >> 440
> >> >>
> >> >> very poor.
> >> >>
> >> >> Thanks again an advance for your experiences and thoughts.
> >> >>
> >> >> 73 JIM KA2AJH
> >> >>
> >> >>
> >> >>
> >> >> ------------------------------------
> >> >>
> >> >>
> >> >>
> >> >> Yahoo! Groups Links
> >> >>
> >> >>
> >> >>
> >>
> >>
>
--
Cort Buffington
H: +1-785-838-3034
M: +1-785-865-7206
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