Topband: Beverage feedline

[Michael Tope]

Timo,

According to ARRL's TLW program, your RF insertion loss for 1500ft of 
RG-6 cable should be around 7dB. This is based on Belden 8215 which uses 
a solid dielectric which makes it more lossy than your 1189A which is a 
foamed dielectric, but less lossy than 1189A because it uses a copper 
shield whereas 1189A uses an aluminum shield. These two opposing factors 
seems to balance out as TLW predicts about 10% greater loss for 8215 
than does the loss vs frequency table on the 1189A data sheet, so if 
anything 1500ft of 1189A at 1.8 MHz might be a bit better than the same 
length of 8215.

If you want to run DC thru this cable to power a switch or pre-amp, the 
loop resistance (inner conductor + shield) for 1500ft will be around 49 
ohms. For a 100mA load that will be ~5 volts of drop between the source 
and load.

FWIW, 1189A doesn't appear to be rated for outdoor use whereas 8215 is 
rated for direct burial. OTOH, 8215 uses an all copper shield so its 
probably very expensive compared to the aluminum shield cable (like 
1189A) used by the CATV industry.

I buy 1000' rolls of Commscope F660BEF Gel Coated Direct Bury RG6 from 
these guys for $48 US per roll (I think this is the same stuff 
recommended by W8JI):

http://www.ebay.com/itm/CommScope-F660BEF-Direct-Burial-RG6-Cable-Flooded-Coaxial-Undeground-Gel-Coated-/160693197034?pt=US_Video_Cables_Adapters&hash=item256a0f98ea#shpCntId

It looks like they ship to Finland if the overseas shipping doesn't 
raise the price too much (UPS shipping is $25 just to go a few miles 
from Phat's warehouse to my door here in Los Angeles). Perhaps there is 
a cableTV/satellite distributor closer to Finland with better terms.

73, Mike W4EF.............

On 6/26/2014 8:12 AM, Timo Korhonen wrote:
> Hi all,
>
> We are putting up new beverages for 160/80 at OH5Z.
> I have a question regarding the feedline. We have to make
> quite long runs like 1500 feet.
> When looking for a low cost 75 ohm coaxial I found a Belden
> RG6 type cable which is reasonably priced.
>
> Here is a link for technical data
>
> http://www.farnell.com/datasheets/1733139.pdf
>
> This cable has a copper covered steel inner conductor.
> Is this an issue on low frequency like 1.8 MHz with long runs like 
> 1500 feet?
>
> Thanks for your help
>
> 73, Timo OG9X
> oh5z.wordpress.com
>
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