Topband: RX Power over Coax

[Sam Josuweit]

Does anyone have an audio recording of what micro-arcing sounds like they could post somewhere?

Sam(N3XZ)

-----Original Message-----
From: Topband [mailto:topband-bounces+samjos=epix.net at contesting.com] On Behalf Of GEORGE WALLNER
Sent: Wednesday, October 07, 2020 10:05 AM
To: Dennis W0JX; Dennis W0JX via Topband
Subject: Re: Topband: RX Power over Coax

I use a 600 foot long run of CATV coax to power a remote pre-amp at the 
DHDL-s, delivering +12V/100 mA via the central conductor (return via the 
shield). Prior to installing the F plugs I spray the cleaned and prepped 
ends of the coax with DeOxIt. I also spray the inside of the female F 
connectors. I add a small amount of SS-30 grease to the thread of the each F 
connector, tighten the connector using a small wrench (!) and tape the 
outside of each mated F connector.
So far, no no noise, micro-arching or other.
Further, I believe that the DC current keeps the contacts vetted, which 
makes them more reliable.
73,
George,
C6AGU/AA7JV



On Tue, 6 Oct 2020 04:44:51 +0000 (UTC)
  Dennis W0JX via Topband <topband at contesting.com> wrote:
> Regarding the issue of voltage over coax to power the preamps used at the base of short verticals, Lee, K7TJR, developed an alternative power feed system for his new SMD preamps using a separate RG6 coax. Apparently, K3LR is using such an approach to avoid sending voltage down the coax in his 8 element HiZ array at his contest station.
> DXE has begun selling the new version 2 preamps but the description in their catalog does not mention this separate power feed system. The older HiZ preamps, and the YCCC preamps, can probably be modified to the voltage with a separate wire from the combiner box to each vertical antenna preamp.
> One question I have with this approach is whether an external power wire would also need a common mode choke on it.  Perhaps Lee could offer some opinions on this alternative power approach.
> 73, Dennis W0JXMilan, OH
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