Topband: 2-element receiving arrays

Fri Mar 31 19:34:41 EDT 2023

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 <ve6wz at shaw.ca> 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 <donovanf at starpower.net> 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" <k3mm at verizon.net> 
> > To: "Frank W3LPL" <donovanf at starpower.net>, "topband" <Topband at contesting.com>, "PVRC" <pvrc at mailman.qth.net> 
> > Cc: "Pete N4ZR N4ZR" <pete.n4zr at gmail.com> 
> > 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 <donovanf at starpower.net> 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 care required to suppress common mode signals (buried feedlines are highly recommended) 
> > - negative effects of nearby trees and buildings. 
> > 
> > The primary advantages of low impedance verticals are 
> > - much stronger signal levels 
> > - much less criticality of common mode signal suppression, 
> > - much lower cost 
> > - much higher reliability 
> > - immunity to lightning damage 
> > - much less affected by nearby trees and buildings 
> > 
> > The primary disadvantages are 
> > - taller verticals (typically about 24 feet) 
> > - radials (they can be very short if many radials are used) 
> > - mono band operation (switchable matching networks can be used for multi-band operation). 
> > 
> > I highly recommend the DX Engineering Receiving Antenna Phasing System. 
> > Its expensive but well worth the investment especially for a small array. 
> > 
> > [ https://www.dxengineering.com/parts/dxe-ncc-2 | https://www.dxengineering.com/parts/dxe-ncc-2 ] 
> > 
> > If you have 120 feet for a three element array, the YCCC array is a great choice 
> > It can use high impedance or low impedance verticals 
> > Unfortunately its no longer available from DX Engineering 
> > The nine element YCCC array uses only three active elements at any time, 
> > so its really a three element array switchable in many directions. 
> > 
> > [ https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf?_gl=1*1cv0fc9*_ga*MjEyMDA1Nzc3MS4xNjUyMzAyMjc0*_ga_NZB590FMHY*MTY4MDE5NTk1OC40My4xLjE2ODAxOTYwNTYuNTAuMC4w | https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf?_gl=1*1cv0fc9*_ga*MjEyMDA1Nzc3MS4xNjUyMzAyMjc0*_ga_NZB590FMHY*MTY4MDE5NTk1OC40My4xLjE2ODAxOTYwNTYuNTAuMC4w ] 
> > 
> > [ https://www.youtube.com/watch?v=dl-crM5Kb6A | https://www.youtube.com/watch?v=dl-crM5Kb6A ] 
> > 
> > [ https://www.youtube.com/watch?v=lVW1CmrzP7c | https://www.youtube.com/watch?v=lVW1CmrzP7c ] 
> > 
> > A two element array occupies only 60 feet or even a little less. 
> > 
> > 73 
> > Frank 
> > W3LPL 
> > 
> > 
> > ----- Original Message ----- 
> > From: "Pete N4ZR N4ZR" < [ mailto:pete.n4zr at gmail.com | pete.n4zr at gmail.com ] > 
> > To: "topband" < [ mailto:Topband at contesting.com | Topband at contesting.com ] > 
> > Sent: Thursday, March 30, 2023 12:54:30 PM 
> > Subject: Topband: 2-element receiving arrays 
> > 
> > Thinking ahead to next winter on 160, I'm interested in replacing my 
> > K9AY Loop with a 2-vertical phased array. I'd like to homebrew the 
> > antennas and just buy or build the remote control unit for the shack. 
> > I'm looking for sources of components (antenna-located preamps and an 
> > in-shack controller), and would prefer not to completely homebrew them, 
> > but the prices at the usual suspects are awfully high. Any ideas? 
> > 
> > I have pretty reasonably-priced access to 25 and 31-foot fiberglass 
> > poles (used for wind-socks by model airplane enthusiasts). I'm thinking 
> > that one relatively low-cost approach might be to attach, say, #14 wire 
> > to the poles, with preamps at the base, but wonder if there is a 
> > downside to using such small-diameter antenna elements rather than 1 or 
> > 1.5 inch tubing? Alternatively, are clones of the DX Engineering 8' 
> > short verticals with preamps a good alternative? 
> > 
> > -- 
> > 73, Pete N4ZR 
> > _________________ 
> > Searchable Archives: [ http://www.contesting.com/_topband | http://www.contesting.com/_topband ] - Topband Reflector 
> > 
> > BQ_BEGIN
> > 
> > 
> > 
> > BQ_END
> > 
> > 
> > _________________
> > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector