[amsat-bb] Feed Line Loss @ Freq vs. Price

Wed May 9 17:51:39 PDT 2007

To any one interested , I just did some comparisons to 3 different cables @
146, 435 & 1268.100 Mhz for any one that might want the info.

Andrews LDF4-50A ½” Hardline Loss

@ 1268.100 Mhz 40’ = 1.01 DB Loss

@ 435.100   Mhz 40’ = 0.568 DB Loss

@ 146.000   Mhz 40’ = 0.3212 DB Loss

LMR-600/CNT-600

@ 1268.100 Mhz 40’ = 1.16 DB Loss

@  435.000  Mhz 40’ = 0.68 DB Loss

@  146.000  Mhz 40’ = 0.40 DB Loss

LMR-400/CNT-400

@ 1268.000 Mhz 40’ = 1.8 Db Loss

@   435.100 Mhz 40’ = 1.08 Db Loss

@   146.000 Mhz 40’ = 0.60 Db Loss

Now for the interesting info
..

COST

40’ Andrews LDF4-50A (Hardline)Terminated with dual ‘N’ Male connectors -
$98.34 +  Shipping

40’ LMR-600/CNT-600  Terminated with the same ‘N’ male – $111.30 +  Shipping

40’ LMR-400/CNT-600 Terminated with the same ‘N’ male - $ 49.78 +  Shipping

Note the Shipping charges to my location were the same regardless of cable
type @ 13.82 pr/run

I posted this info for an interesting comparison.. the best cable (of the
three) is cheaper than the 2nd lowest loss cable!!! The reason I took the
freq so low was for those whom may want to run a tx converter on 146 or 435
for a 1268 uplink.

For me, none of theses cables @ 40’ provide low enough loss to run 1268Mhz
from in the shack.. trying to keep the loss below 1.0 db. Just at a glance
you could gain .0788 DB running a 146 I.F. to a TX converter or  .112 db
running a 435 Mhz I.F. to a tx converter with the Hardline. A total loss of
between 1.01 dB – 1.18 dB by running 1268Mhz In shack, depending on the
cable. However a .32 db feed loss on 1268 (running a rx/tx converter on
146Mhz) is OUTSTANDING if you run the ½” hardline.

Also keep in mind that as long as your I.F. dosen’t change, neither will
your loss! 

The cost difference is $ 12.96 . ( how ironic ) Between the Hardline &
LMR/CNT-600

A lot of people use the LMR-400/CNT-400  which is less expensive yes, but
with ½ dB more loss on 146 ,  1 dB more loss on 432 , & a whopping 2 dB more
loss on 1268 vs. the LMR-600/CNT-600 cable, slightly more vs. the Hardline
it dosent seem logical to run it for an in shack, microwave application. (
see below actuall watt loss )

Now that’s the raw dB #’s
 lets break this down to good ole fashon WATTS!

Now, for uplink  @ 1268.100Mhz loosing 5.244 watts dosent seem like much,
however.. try looking for an amp for $ 48.56 Cents, the difference ‘could’
be a SSB uplink quality ( if your running 1268Mhz in shack )

40’ of Andrews LDF4-50A with 15 watts in @ 1268.100 =  11.88 Watts at the
other end  / 3.12 Watts lost

40’ of LMR-600/CNT-600   with 15 watts in @ 1268.100 =  11.355 Watts at the
other end / 3.645 Watts lost

40 of LMR-400/CNT-400    with 15 watts in @ 1268.100 =  9.756 Watts at the
other end / 5.244 Watts lost or OVER 1/3rd of your R.F.

40’ of Andrews LDF4-50A with 15 watts in @ 435 =  13.156 Watts at the other
end  / 1.84 Watts lost

40’ of LMR-600/CNT-600   with 15 watts in @ 435 =  12.867 Watts at the other
end / 2.133 Watts lost

40 of LMR-400/CNT-400    with 15 watts in @ 435 =  11.762 Watts at the other
end / 3.238 Watts lost 

40’ of Andrews LDF4-50A with 15 watts in @ 146 =  13.928 Watts at the other
end  / 1.072 Watts lost

40’ of LMR-600/CNT-600   with 15 watts in @ 146 =  13.741 Watts at the other
end / 1.259 Watts lost

40 of LMR-400/CNT-400    with 15 watts in @ 146 =  13.068 Watts at the other
end / 1.932 Watts lost 

All said and done, this should provide at least 3 points:

#1 Mast mounted TX / RX converters excellent way to save valuable db ! 

#2 The expensive stuff may not be the best stuff !

#3 Good cable may save you running a Pair of antennas or an amplifier !

Cable Type, cable loss , power &  freq calculator @ -
http://www.ocarc.ca/coax.htm

The prices here are from a well known custom cable company ( not listed
because im not affiliated with them, nor do I want to advertise for them )

Hope this was informative ! 

-Steve Raas

N2JDQ

FN20vg

http://n2jdq2007.tripod.com/