Best MWDX antenna?

[~SIGINT~]

Rob, I'll be interested to hear about your switch when it arrives. I have been thinking of one as well for the past little while. I even found one that has a balun which converts the RF onto a CAT-5 cable and back out to a connector in the house. This caught my attention because running a piece of CAT-5 or CAT-6 is extremely convenient vs. coax. The telephone company has been doing this over twisted pair for 100+ years, why not radio.

[RobRich]

Here is what I ordered:

https://www.ebay.com/itm/202550852561

https://www.ra0sms.ru/p/remote-antennas-switch-with-wi-fi.html

I purchased his last assembled one listed at eBay, but the switch is based on this kit:

https://www.ebay.com/itm/202550867003

I am not sure if he is going to be assembling anymore for eBay. The assembled version still is listed at a his own online store, but I have never ordered from there.

http://ra0sms-shop.ru/product/remote-rx-antennas-switch-with-wi-fi-interface-hf-hamradio-8-to-1

Otherwise the kit appears rather straightforward. I just did not want to deal with building it.

[RobRich]

I am thinking Chris used ethernet cable for feedline with his crossed loop antenna.

http://www.tarluz.com/copper-network/complete-comparison-table-of-cat5-cat5e-cat6-cat6a-cat7-and-cat8-copper-cable/

Common ethernet cable types are rated typically around 100-ohms impedance up to whatever their maximum design frequencies.

CAT-6a STP (shielded) or higher probably would be better if needing improved EMI/EFI mitigation, plus it can be sourced as outdoor direct burial if needed.

There is a listing for CAT-6a STP 500' direct-burial copper cable on a damaged spool for ~$131 shipped at eBay right now.

Specs aside, I would suggest avoiding unidentified cables due to the risk of copper-clad aluminum wire. CCA can suffice for certain wiring purposes, but it likely would make for horrid feedline IMO.

Yeah, I use stranded CCA hookup wire sometimes, but thankfully my larger Audiopipe 18 and 20 "CCA gauge" rolls have proven usable for my basic purposes like on-ground radials, jumpers, etc. Nothing under any significant stress, tight tolerances, or high voltages.

[ChrisSmolinski]

I am thinking Chris used ethernet cable for feedline with his crossed loop antenna.

http://www.tarluz.com/copper-network/complete-comparison-table-of-cat5-cat5e-cat6-cat6a-cat7-and-cat8-copper-cable/

Common ethernet cable types are rated typically around 100-ohms impedance up to whatever their maximum design frequencies.

Yes, the original LZ1AQ amp uses ethernet cable. One pair is for the signal, the other wires are used for power and control signals. The N4CY version I am using now uses a regular coax feed with DC power on the center conductor.

I want to get back to playing around with ethernet for antenna feedlines.

[ultravista]

Now grounded to the top of the mast, too. Did the same thing I did at the bottom of the mast.  o

Did grounding help with the mini whip?

[RobRich]

Chris, thanks for the clarification.

Did grounding help with the mini whip?

I already had the miniwhip grounded to the base of the mast. I added another ground point to the top of the mast, which is where it really should have been grounded to start. I was just building it in stages.

Anyway, yeah, grounding an active miniwhip is incredibly important to the antenna performance. Think of the ground as the other "half" of the antenna just like a basic half-wave dipole has two "sides."

If you do not provide a decent RF ground path, then the miniwhip primarily uses your coaxial feedline as its RF ground via common mode. Sometimes that works okay, but for many deployments that introduces increased EMI/RFI in to the situation. A miniwhip relies on a high-gain preamp for its performance, and that is already putting an increased noise profile into the receive path. Also there is the issue of a miniwhip being an e-field antenna, thus being particularly susceptible to local EMI/RFI coupling. You want to limit noise ingress as much as possible. Improving RF grounding and feedline decoupling are good places to start.

The 10.5' masts for my active whips have provided enough RF grounding for my particular deployment and casual listening purposes IMO. However, going to an extreme, look at what the popular Twente WebSDR does. Its active minwhip if RF grounded to a large metal roof of a building at 20 meters height above ground. o.0

http://websdr.ewi.utwente.nl:8901/qrt.html
http://www.pa3fwm.nl/technotes/tn09d.html

[RobRich]

YCCC-style preamp deployed on the 31' vertical. The antenna is little large for the intended preamp design, plus I bonded the RF ground to my existing sixteen ~31' ground radials instead of just a ground rod as intended by the designer. In other words it is dealing with more input gain than intended, though it is handling it okay thus far.

I noted a few trivial harmonics from whatever flamethrowers, but just attenuation usually knocked it down, and it is something I deal occasionally with even without a preamp. Radio Rebelde and Radio Marti might as well be locals with their over S9+60 signals at times. o.0

Gain is slightly up in some bands and slightly down in others. I figured that might happen. It is not a high-gain preamp, but instead it is designed to create a ~75-ohm feedpoint…. technically for a multi-antenna phased array. Just one antenna here. Anyway.

I get why the array design suggests a moderate-gain preamp after the phasing unit. No big deal IMO, as I usually have a MFJ-1020B in-line with that antenna if really needed. I might look into a better preamp later.

The biggest plus I have noted thus far is an improved noise floor, especially at lower HF and MW frequencies. Signal levels aside, actual SNR on lower frequencies seems better than even my 148' LoG, though I would need to hookup a SDR to get actual numbers.

[RobRich]

SNR is good, but signal levels have dropped considerable on 80m and 160m. Booming signals are now like S1, and many are not even moving the S meter.

Normally I could not care less about S readings, but my primary R-2000 receiver is only so sensitive.

The MFJ-1020B is great for dealing with a significant mismatch on a highly negative-gain antenna, like with my LoG if (rarely) needed. However it is not too great with this YCCC preamp setup, and constant retuning a preselector is not my idea of fun.

I am not spending $150+ on a decent preamp for mostly casual listening, and I do not feel much like building one, so I ordered a Noolec HF preamp. I have no idea what chip it is using, but at least it supports multiple power feed options and has a RF limiter circuit. I will try it inline near the receiver, since coax loss on 80/160 is minimal. If it looks okay, I can derive 5v from the 12v bias tee of the YCCC and place it near the antenna feedpoint sometime.

If I do not like the results, I likely will be putting the 4:1 unun back at the 31' vertical feedpoint. Maybe then later deploy the YCCC as designed with a smaller vertical and just a ground rod as I have a S9v18 collecting dust. That probably will need a second preamp as well, but at least the YCCC input side will have a match and input gain much closer to what it expects.


BTW, about MW in particular, the YCCC appears to excel there. I only took a quick skim, but I could tell signal levels were improved with no perceived loss in SNR. LW looked good as well, including noting several NDBs. I would leave the setup as is if I wanted only a MW/LW solution, as no doubt the YCCC cleans up the match down there, especially compared to my usual 4:1 unun setup at such low frequencies.

[RobRich]

Looks like the YCCC unity-gain feedpoint preamp is staying on the 31' vertical for awhile longer. The Nooelec HF preamp picked up the gain as expected. I am powering it via an Apple USB 5v power supply.

I know there has to be a SNR change, but so far it is not glaringly noticeable, so whatever for now. Largely just improved signal levels, which the setup needed with my usual Kenwood R-2000 receiver IMO. Currently listening to a 75m QSO.

That said, the 4:1 unun might back over the weekend if I feel like bothering with it.

[~SIGINT~]

Rob, good to know about the Nooelec preamp. I was thinking of getting one on my next order just to play with. If you reacall, way back towards the start of this post, I had mentioned that I have Nooelec Flamingo filters and that I was, and still am, happy with them. I have both the AM and FM in series with the input to the SDR.

[RobRich]

The Nooelec HF preamp does seem decent for the price. It is hardly high-end, but it does have RF shielding and a purported RF limiter. I am not testing the limiter. ;p

The 4:1 unun is back on the 31' vertical. The YCCC preamp probably helped best around low MW down into LW, and that makes sense given the impedance mismatches alone. However, as noted earlier, it nosedived my low-HF signals compared to the 4:1 unun. So out it goes, and back to the known setup.

I am hoping to one day soon deploy the WiFi-enabled antenna switch. It should help clean up some of my multiple feedlines, or just allow me to deploy yet more antennas. ;) I know my deployed 9' vertical is not connected to anything right now, plus I have an S9v18, a MLA-30 loop, a Chinesium miniwhip, a FM BCB crossed dipole, a small discone, etc. collecting dust and needing deployed.

Also I have a Radio Shack version of an Antron 99 in storage. Alternatively, I have a couple of 11m/10m mobile verticals that would suffice for an easy horizontal dipole on a tripod, too.  Either way I have been thinking about making a portable setup for a little 11m SSB talking at the beach if/when it over cools down.

[RobRich]

It is hardly a strong signal, but FIS 332KHz from Key West is copyable tonight on the Kenwood R-2000 via the 31' vertical. No preamp or preselector needed.

Heard some others. Just happens FIS is close enough and powerful enough to be a quick catch here.

That said, it is not a copy on the 148' LoG. Hmmm. Might have to do a VNA sweep there to see if something is wrong. Admittedly, it has been deployed for years and is almost more like a loop-in-ground these days.


Popped the Nooelec HF preamp in line with the 31' vertical to do a quick check for overload. FIS still was there, but I did use a 10dB attenuator at its input to cleanup up a little splatter from whatever MW or tropical-band flamethrower. Not bad for a basic $25 preamp IMO.

[NJQA]

That said, it is not a copy on the 148' LoG. Hmmm. Might have to do a VNA sweep there to see if something is wrong. Admittedly, it has been deployed for years and is almost more like a loop-in-ground these days.

Remember that LoG and BoG antennas need to sit ON GROUND and not under it.  When they get subsumed into the ground, performance suffers.  See Figure 39 here:

https://rudys.typepad.com/files/qexjul-aug-2016-bog.pdf

[RobRich]

Yeah I know. Here is it more like accumulating pine needles and shifting sand. I do not bother cleaning them off since it is in the edge of a wooded area. I might eventually get around to taking the leaf blower to it.

[RobRich]

I know greyline, but still, the MUF here has been falling *quick* in recent nights. Earlier tonight I was listening easily to 16m broadcasts from Asia to way after dark, but now even Cuba on 13460 in the 22m band is a rough copy as the local estimated MUF is down already to 12MHz. I suspect it will drop towards or into single-digit MHz in another hour to two.


Down to 11MHz here. Part of NA is down in to single digits.


Getting there. Floating around 10-11MHz. Part of interior NA is down to 8MHz.

BTW, a link for those following along:

https://prop.kc2g.com/