I received a few private emails asking similar questions about my power
redesign of my amps.
I need to clarify this.
Yes, I have redesigned a version of a HI-Z amp that does not use 12v on the
coax. Each require a dedicated 12v supply line.
I right now have about 15 of these amps deployed in the field for my new BOG
broadside phased array system.
I have not yet swapped out the amplifiers on my 9C for a redesigned model
because so far they have remained noise stable. However, all the amps in my 9C
have had the PCB judiciously cleaned and carefully coated.
Another question was have I actually seen this noise problem from micro-arcing?
The answer is yes. Absolutely. In some cases it became very bad. In all cases
this was on poorly cleaned and un-coated PCBs that developed moisture. On at
least 5 of the amps I could actually see what looked like galvanic corrosion
developing at the F-connectors on the PCB. A white dusty powder had developed
across the connector. This was not because of serious water intrusion, but
just moisture and humidity developing in the boxes. If some day I switch out
the amps I have now, I will not use a bias-T voltage supply.
As for modifying the combiner not much is required except to snip the RFC at
each f connector and supply 12v through an RFC to the supply line going to each
amp.
Steve, Ve6wz
From Babcocks iPhone
> On Mar 30, 2023, at 6:31 PM, VE6WZ Steve wrote:
>
> I strongly second Franks comment about weather proofing.
>
> Equally important on any outside electronics is to very carefully clean ALL
> the residual flux off the PC boards, and especially on the F-connector solder
> pads.
> ALSO, apply some acrylic conformal coating on all outdoor PCBs.
>
> With 12v on the coax line with a bias-T setup, even small amounts of dirt
> stuck to old flux and then combined with moisture can cause serious noise
> issues with micro conduction between the centre conductor and ground pads.
>
> I have since redesigned all my rx amplifiers to use a separate 12v dedicated
> supply voltage to keep the DC off the coax.
>
> 73, Steve Ve6wz
>
> Sent from my iPad
>
> > On Mar 30, 2023, at 2:18 PM, Frank W3LPL wrote:
> >
> > Tiler,
> >
> > Congratulations on your new five circle YCCC array!
> >
> > Be sure you very effectively waterproof all of your coaxial cable
> > connectors
> > that carry DC power. Even the slightest amount of moisture in the
> > connectors
> > will cause micro-arcing of the DC voltage, raising your noise floor by many
> > dB.
> >
> > 73
> > Frank
> > W3LPL
> >
> >
> > From: "K3MM"
> > To: "Frank W3LPL" , "topband"
> > , "PVRC"
> > Cc: "Pete N4ZR N4ZR"
> > Sent: Thursday, March 30, 2023 8:08:42 PM
> > Subject: Re: Topband: 2-element receiving arrays
> >
> > I just completed building a YCCC nine Circle array using V E6WZ PC boards
> > with the latest mods, including on board chokes. I actually have it
> > deployed currently as a five circle As I’ll be taking it down soon for
> > mowing season, but it works quite well. The patterns on all three bands,
> > 160 through 40 are as advertised. Very good patterns but not the best
> > sensitivity . I built mine as about 23 foot verticals. I’d say compares
> > favorably to my 500 foot beverage, antennna although it requires a lot of
> > pre-amplification. Due to the active electronics it can be overloaded by
> > close transmit antennnas so perhaps not as useful for a multiband operation
> > in a small area.
> > I’m providing power over the coax cable and using green heron everywhere,
> > wireless remote control, which works quite well and is controlled by the PC
> > software using a mouse or hotkeys.
> >
> > It was a fun project. It turned out quite well, but not in expensive. I
> > scrounged about half the aluminum tubing and angle I’m using for the bases
> > and probably spent $1500 or so. including the remote control hardware. next
> > fall, I’ll deploy the full nine circle array, but the five circle is
> > probably almost as useful and avoids some complexity and cost. i’ll also
> > probably relocate it to get more separation from some of the transmit
> > antennnas.
> >
> > Ty K3MM
> >
> > [ https://apps.apple.com/us/app/aol-news-email-weather-video/id646100661 |
> > Sent from the all new AOL app for iOS ]
> >
> >
> >
> > On Thursday, March 30, 2023, 1:38 PM, Frank W3LPL
> > wrote:
> >
> >
> > Hi Pete,
> >
> > For a monoband receiving array, you might consider using low impedance
> > resonant verticals rather than high impedance verticals.
> >
> > The primary advantages of high impedance verticals are
> > - very short verticals (but taller verticals produce stronger signals)
> > - multi-band operation
> > - no radials
> >
> > The primary disadvantages are
> > - reliability issues with outdoor electronics
> > - lightning susceptibility of outdoor electronics
> > - higher cost
> > - much lower signal levels
> > - extreme
