Loops Mini review: W6LVP active loop

[nanZor]

prcguy - you got me thinking about another application for the LVP loop:

Use it as the "sense" or auxiliary antenna for phasing noise cancellers like the MFJ 1025/1026 or Timewave units.

Sometimes even with these phase cancellers, one can't obtain a phase cancellation if their "sense" antenna is large physically, or electrically random due to common-mode current on the sense antenna feedline.

The nature of a small vertical loop - if properly constructed usually means less common mode interaction. Thus you have a small "point source" in reverse for this application with a phase canceller, and may now obtain a cancellation where you couldn't before.

Rotating the loop to accentuate / null offending signals, from this "point source in reverse" may help one obtain a phase cancel.

I haven't tried this, but just thinking out loud for those who may have tried one of the phase cancellers and not been successful when there is qrm coming in from all directions. Using the LVP loop as the auxiliary sense antenna might be very interesting.

 

[VE2XWA]

Just ordered my W6LVP! Thanks to PRCGUY!

After exchanging several emails with Larry he check where im living and found out there’s seven 50 000w AM radio stations within 20km of me so he suggested to install an high pass filter on the antenna. What i accepted. So my loop will be covering 1800khz to 30mhz.

Dan

Cant wait to experiment with it.


Sent from my iPhone using Tapatalk

 

[Turbo68]

I just ordered mine today and Larry said he will ship it to australia on saturday cannot wait till arrives..

Regards Lino.

 

[SDRPlayer]

Looking forward to a local review Lino!

 

[Turbo68]

I will have got the wellbrook active loop to compare it too and a few pk loops dipoles..

Regards Lino...

 

[SDRPlayer]

awesome, the Wellbrook and W6LVP are both big investments for me and i would appreciate your appraisal.

 

[mm]

I had the w6lvp loop and it did not make any improvement for me from 160 to 10 meters as compared to other antennas that I have.

I tried it in a location where I have moderate to high noise and I had it up high at 30 feet on a rotator, lower on my deck also on a rotator and in 3 different areas on my property at 10 feet also on a rotator.

The rotation of the LVP loop is just to sensitive and finding a suitable null is time consuming and even when a null was found it didn't really help null noise and bring the received signal up.

I then used the LVP loop as a noise/aux antenna with my MFJ126 and then a mfj1025 noise cancellers and it had zero effect on reducing/nulling the noise.

I could not find a location nor any configuration where the w6lvp loop reduced my noise to an acceptable level as compared to my present antennas which are noisy end feds, shortened and various full sized noisy vertical antennas.

In the winter of 2017 to 2018 I spent 4 months on 7.156 MHz at nights trying to null noise on ZS6D, then later on 7.192 trying the same with I2VRN so that I could at least receive them better and in no case did the w6lvp loop enable me to improve my reception, it just does not work suitably at nulling noise and improving S/N.

In my case i sold the w6lvp loop to a local ham who doesn't have any other antennas for his desired use, used it for a swl antenna on buisness trips and nothing else.

I then went to a 3 array of shortened/active phased verticals which so far is the only antenna that has been able to reduce my noise simply because of it's proven directional properties.

 

[ka3jjz]

Why in the world did you mount it so high? Loops like these are generally kept pretty close to the ground. No doubt you were fighting not just local noise issues, but noise being propagated from skywave. A loop generally loses its directionality the higher you go in frequency. This is because skywave tends to be the dominant mode of propagation as go higher on HF.

No wonder you couldn't get a good null.....Mike

 

[prcguy]

Sounds odd that he was not happy with the loop but if the "noise" he was trying to null out was everywhere then there will be no null. I tried my W6LVP loop in my house around noisy stuff and was able to hear lots of HF and AM BCB that I otherwise could not with any other antenna. I nulled noises from specific items in my house just fine and it made reception very nice.

My W6LVP loop now sits on my roof with a rotor stuck to a vent pipe. I can null out big AM broadcast stations a good 30 to 40dB with no problem and its very predictable when rotating, the signal will gradually start to go down then the signal will head into the dirt very quickly as you get within a few degrees of maximum null. I find it very easy to use and the null can be very useful for reducing interference.

I also have very effective RF chokes on the feedline exiting the W8LVP loop amplifier. I think this is very important because in some cases and with many antennas, the feedline can become part of the antenna and this will destroy any nulling function of the antenna.

 

[jlh]

prcguy, do you have the rf choke connected right at the amplifier or where the coax meets the radio?

Thank you

 

[prcguy]

I have both, a My Antennas CMC-0510-R at the antenna end and a home made choke at the radio end. On other antennas here I've seen a noticeable decrease in noise and birdies placing a good RF choke at the antenna end and a further reduction of noise with another at the radio end. Every situation will be different but its worth a try. You will not know what works until you try it.

prcguy, do you have the rf choke connected right at the amplifier or where the coax meets the radio?

Thank you

 

[mm]

I mounted it high to see if there were multiple noise sources coming from many directions because low to the ground it had zero nulling.

At ground level I then moved it around my property low to the ground and in all locations high and low to the ground but still I did not measure any s/n improvement at any height and in any location.

Other things tried, various Feedline chokes, different coax even tried a spare section of 1/2 inch hardline with the feedline chokes on short flexible sections of rg213 feeder cable mainly because winding harline chokes is impossible.

I did the hardline coax in a final desperate attempt to see if possibly something was coming in on the other coax used but still no major s/n improvement was found.

I then tried different diameter loops, larger and smaller as mentioned in some of the documentation provided by LVP all tests were redone in the various above mentioned locations but still no improvement and it was then that a friend feeling sorry for me let me use his DX engineering 3 active vertical array when he was in a qth move and this is what worked for me.

Eventually I of course had to give the 3 vert array back when he settled in to his new qth but not before a bit of reverse engineering and some scribbled notes.

For > 200 dollars I considered the LVP to be a waste of money especially if you look at what is inside.

Again in my situation it didn't work and I sold it for a loss but put the money I received into parts for my own 3 shortened active vertical switched array which is what works for me.

The stock dx eng active antenna system while it is very good, it like the LVP loop was just way to expensive and I didn't feel like wasting anymore money on store bought antennas that are poor performers.

 

[jlh]

Thank you prcguy and mm

 

[jlh]

One more question and Moderator, if I’m taking this thread too off-topic, please delete my post. This thread is a good resource for anyone interested in this loop.

Should the coax shield be grounded on a loop like this?

Thank you

 

[prcguy]

If you mount the loop outdoors it should be grounded per NEC article 810. This can be a ground block or lightning arrestor in the coax with a short run of 10ga wire from the arrestor to the house AC entry panel ground. This can also induce noise onto the coax which can be picked up by the antenna and a good common mode choke in the coax between the arrestor and antenna can help reduce noise pickup.

One more question and Moderator, if I’m taking this thread too off-topic, please delete my post. This thread is a good resource for anyone interested in this loop.

Should the coax shield be grounded on a loop like this?

Thank you

 

[jlh]

Thank you prcguy

 

[Turbo68]

I received my loop today and so far hf aero has been very impressive on all bands even on 3.470 which i have never heard anything in the 30 years i been monitoring hf aero picked brisbane & bali loop is 1 metre high and on the instructions Larry wreckins between 6 to 20 feet high works best just wondering i am using rg58 also have a few runs of lmr400 witn bnc on each end would that improve the performance of the loop...

Regards Lino.

 

[SDRPlayer]

Thanks Lino, please keep us updated. I plan to buy a loop sept/oct so your input is valued.

 

[ka3jjz]

Here are eHam's comments on the LVP loop - with the T/R switch, but that's secondary for this discussion....

https://www.eham.net/reviews/detail/13215

A 4.9 out of 5....Mike

 

[SDRPlayer]

Thanks Mike, but Lino is in my "backyard" and his evaluation is more relevant to me than anyone stateside. What he can or can not hear at the moment will give me a fair idea.