Topband: RG6 recommendations

[John Kaufmann]

Hi Charlie, 

What you see in your TDR sweep of the RG6 is absolutely normal.  I've seen exactly the same thing.  The rise in apparent impedance with distance is caused by the loss in the cable.  If you had a lower loss cable, the TDR trace would be flatter.  As long as you don't seen any significant bumps or dips, your cable run is fine.

For use with Beverage antennas, the loss in the RG6 is inconsequential unless maybe you have an extremely long run of cable (thousands of feet).   

73, John W1FV

-----Original Message-----
From: Topband [mailto:topband-bounces+john.kaufmann=verizon.net at contesting.com] On Behalf Of Charles Stackhouse via Topband
Sent: Sunday, January 24, 2021 8:33 PM
To: topband at contesting.com
Subject: Topband: RG6 recommendations

After a period of inactivity, I set out to get my station going again. The Beverages were not working with very low signal levels and I replaced 600 foot RG6 feedline from shack to Beverage switch in the woods with new RG6 which still had the plastic wrap around the spool.
I was surprised when things were no better. The "new" coax is not right. The TDR sweeps show a straight line increase in impedance from 78 ohms to 95 ohms. There are no impedance "bumps" seen. The 400 feet left on the spool do the same thing as does 800 feet of the same stuff bought at the same time.
This stuff was bought on Ebay and is gel-flooded RG6 labelled "Commscope Inc. GA390709 and GA3907022." I bought it in Sept 2014 and it has been stored ever since in a dry heated basement.
Using an oscilloscope as a TDR I see that the impedance line is not level as with good coax but slopes  upward at an angle.  I also checked by placing a 330 ohm resistor at the end of the cable and ran an SWR trace from 1-8 MHz with the SWR only 2-2.5. 
Why is this cable so lossy? Was it bad to begin with or did it deteriorate in 7 years?
What recommendations for good RG6 can anyone make. There has been lots of critter chewing upon cables in the past so I guess gel-flooded cable would be preferable. Should I spend $230 for DXEngineerings good stuff or can I get by cheaper? 
p.s. I went out and checked each Beverage at the switchbox today and 4 out of 6 were great. Only 3" of snow and temp was about 25 deg F. I was able to keep the snow and dielectric grease off of my laptop.
73, Charlie W2GN
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