[NLRS] 1.2 GHz Heliax question

[John Kalenowsky]

Well, looking at the chart that Mary pointed us, too - Russ would be
looking at > 2dB loss for 70', and about 1.3 dB loss for 50' with LDF4.

With LDF5 (even though it's no longer available) - Russ would be looking at
about 1db loss for 70' and 0.7 dB loss for 50' (but I suspect that other
7/8" heliax type cable losses are similar).

For the relatively short run that Russ is describing, my thinking is that
1/2" Heliax would be fine - certainly better than LMR400 at about 4db loss
per 100' around 1296 MHz (though LMR900 looks somewhat similar in loss to
LDF4).

Don't forget the WEIGHT of the cable and consider flexibility for rotor
loops.

73, JK


On Sun, Feb 23, 2020 at 2:01 PM Mary Brown <maryalanab at gmail.com> wrote:

> Loss chart LDF4-50
>
> https://www.commscope.com/product-type/cables/wireless-transmission-cables/w
> ireless-cables/itemldf4-50a/
> <https://www.commscope.com/product-type/cables/wireless-transmission-cables/wireless-cables/itemldf4-50a/>
> a preamp at the antenna is a must...
>
> -----Original Message-----
> From: nlrs-bounces at mailman.qth.net [mailto:nlrs-bounces at mailman.qth.net]
> On
> Behalf Of Russ Ramirez
> Sent: Sunday, February 23, 2020 1:56 PM
> To: nlrs
> Subject: Re: [NLRS] 1.2 GHz Heliax question
>
> Jon/Barry, At most 70' if I am able/allowed to go to 50' of tower, or more
> like 50' if I have to limit tower to 30'.
>
> Russ
> K0WFS
>
> On Sun, Feb 23, 2020 at 1:50 PM Barry Malowanchuk <ve4ma at shaw.ca> wrote:
>
> > As Jon said..how long is the cable run?
> >
> > Putting TX amplifiers on top of towers is pretty extreme and not
> > recommended unless you want to do EME .
> >
> > 1/2 LDF or 7/8 LDF is excellent for most ham use. 1296 is pretty
> > amazing for propagation and a few dB of feedline loss is not a big deal.
> >
> > Barry VE4MA/ W7
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