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HF Active Loop Antenna V4
Mike Kaylor
I have a very keen interest in the V4 Loop Antenna for use with my RSPDuo running as a Panadapter.
I live in an urban environment and have a lot of power line noise that appears to be horizontally polarized, just behind my home. I recently went from using a Chameleon EFHW to a DX Commander Classic and it dropped my noise floor significantly. Next, I went from a RSPdx to a RSPDuo for it’s dual diversity capabilities and this helps in certain situations. I can now do some SSB communications but still have a lot of noise and fading issues.
This design using smaller loops is very clean and professional looking. It would be easier to hide outside in an HOA environment. I am just trying to get my head around the pros and cons of the smaller dual loops vs a larger 1m loop. I understand it acts as a wider loop and that should lowers the inductance. Has anyone done a comparison with something like the Wellbrook or MFJ loops?
I believe this antenna will tick all my boxes. I only care about ham bands for the most part. I was on the receiving end of those VLF signals long ago and don’t care about them now. I love the idea of the VHF and Lighting protection. Outstanding reputation. I’ve just not been able to find any info on performance and would very much like to learn a little more.
Thank you kindly and 73’s,
Mike - W5SSN
Chris Moulding
Hi Mike,
From the comparison tests I've run in the workshop the small dual loop is equivalent to a 1m wire loop.
For testing LAA++ amplifiers I have a 3m length of wire in a delta configuration with two large crocodile clips. This gives an almost identical output +/- 2 dB either way across the HF bands compared to a HF Active Loop Antenna v4 tested in the same position.
One point I have noticed is that the nulls are deeper with the dual loop than with a single loop antenna even if the single loop antenna uses heavy LDF4-50A coaxial cable as a loop.
Usually when we release a new antenna customer take up is slow and we send a few samples from the first batch to magazines for review.
This time sales were good from day one. We are now building the fourth batch and I won't send any review samples out until it calms down a bit.
I'm sure that there must be a few v4 loop users on the forum so I'd be interested to hear some feedback as well.
Regards,
Chris
From the comparison tests I've run in the workshop the small dual loop is equivalent to a 1m wire loop.
For testing LAA++ amplifiers I have a 3m length of wire in a delta configuration with two large crocodile clips. This gives an almost identical output +/- 2 dB either way across the HF bands compared to a HF Active Loop Antenna v4 tested in the same position.
One point I have noticed is that the nulls are deeper with the dual loop than with a single loop antenna even if the single loop antenna uses heavy LDF4-50A coaxial cable as a loop.
Usually when we release a new antenna customer take up is slow and we send a few samples from the first batch to magazines for review.
This time sales were good from day one. We are now building the fourth batch and I won't send any review samples out until it calms down a bit.
I'm sure that there must be a few v4 loop users on the forum so I'd be interested to hear some feedback as well.
Regards,
Chris
Keith
hi mike
im in no way a techi but i can give you my opinion on the v4 loop
been using one now for approx 2 weeks, fitted on a 12 foot pole with a rotator
i have had a couple of the wellbrook loops in the past and i think the v4 is as good as the wellbrook
it is possible to null out some of the noise on the band with the rotator and with it being small 14in diameter
it can be made more covert than the wellbrook,
and it is a lot cheaper, build quality on the loop is really good but the bracket which bolts to the pole could be better
my loop is in the vertical position and picks up really well, i live in a built up area with lots of overhead telephone cables and lots of
solar panels etc etc, hope that helps a little for you
best 73, keith in the uk
im in no way a techi but i can give you my opinion on the v4 loop
been using one now for approx 2 weeks, fitted on a 12 foot pole with a rotator
i have had a couple of the wellbrook loops in the past and i think the v4 is as good as the wellbrook
it is possible to null out some of the noise on the band with the rotator and with it being small 14in diameter
it can be made more covert than the wellbrook,
and it is a lot cheaper, build quality on the loop is really good but the bracket which bolts to the pole could be better
my loop is in the vertical position and picks up really well, i live in a built up area with lots of overhead telephone cables and lots of
solar panels etc etc, hope that helps a little for you
best 73, keith in the uk
I received my V4 today and haven't had much time to work with it. It's raining, so this weekend I'll mount it in a more permanent spot; for now it is literally one foot off the ground, sitting in a flower pot. Compared to my W6LVP on a rotator about 17 feet off the ground (hardly a fair test) I'm hearing almost all of the same signals, just a higher noise floor.
But here's my issue- the Bias-T isn't working. Using a 12V, 0.5amp AC adapter (Jameco Linear regulated model) the CCW bias-t is dead. Swapping it for an MFJ-4117 Bias-T and using the same AC adapter, all is well. Should I be using a 12VDC adapter that's center negative?
But here's my issue- the Bias-T isn't working. Using a 12V, 0.5amp AC adapter (Jameco Linear regulated model) the CCW bias-t is dead. Swapping it for an MFJ-4117 Bias-T and using the same AC adapter, all is well. Should I be using a 12VDC adapter that's center negative?
Chris Moulding
The Bias Tee unit is centre pin positive with a 5.5 mm long 2.1 mm centre pin DC connector.
One thing to check is that you are not using a 2.5 mm centre pin connector. That will fit but not make contact with the pin.
If the connector is OK let me know and I'll ship out a replacement Bias Tee unit.
Regards,
Chris
One thing to check is that you are not using a 2.5 mm centre pin connector. That will fit but not make contact with the pin.
If the connector is OK let me know and I'll ship out a replacement Bias Tee unit.
Regards,
Chris
Hi Chris, I just checked the specs on my Jameco AC adapter and they are:
So it would seem the Bias T is defective. (Unless I'm missing something terribly obvious.) I did take the back off and measure voltages. I confirmed 12.11 VDC was coming from my adapter and the board on the Bias T read only .94 VDC.
I'm happy to try anything else you suggest.
Thanks,
Dominic
- Output Connector: 2.1mm x 5.5mm straight Female center positive
So it would seem the Bias T is defective. (Unless I'm missing something terribly obvious.) I did take the back off and measure voltages. I confirmed 12.11 VDC was coming from my adapter and the board on the Bias T read only .94 VDC.
I'm happy to try anything else you suggest.
Thanks,
Dominic
Andrea Dalbagno
Hello Dominic
May I ask you how does it work at LF and in the low NDB band (200 kHz to 500 kHz ca) please?
TIA
73
Andrea IN3IWZ
Il mer 22 mar 2023, 15:43 Dominic Dambro <dominic1967@...> ha scritto:
Just wanted to follow up and add that all is well with my new HF Active Loop Antenna V4. I'm really enjoying comparing its performance with my other larger loops and Chris' product support is just stellar. Couldn't be happier.
Andrea, I must admit I've never done any LF or NDB monitoring (though it sounds fun) but with the built-in RF filtering of the V4- most notably the VLF high-pass filter, the frequency range of this antenna is 500 khz to 55 Mhz. So I'm thinking you wouldn't find its performance in that respect very good at all. I can attest to the dramatic difference below 500 khz when switching from my W6LVP to the V4.
Andrea Dalbagno
Hi Dominic
Very helpful comment, thank you!
...and...yes: monitoring NDBs gives a LOT if fun :-)
Best wishes
Andrea IN3IWZ
Il gio 23 mar 2023, 03:21 Dominic Dambro <dominic1967@...> ha scritto:
Andrea, I must admit I've never done any LF or NDB monitoring (though it sounds fun) but with the built-in RF filtering of the V4- most notably the VLF high-pass filter, the frequency range of this antenna is 500 khz to 55 Mhz. So I'm thinking you wouldn't find its performance in that respect very good at all. I can attest to the dramatic difference below 500 khz when switching from my W6LVP to the V4.
I have been really happy with my V4. One curious thing that I need to learn more about- it works with the included 12V bias t and it also works with the built-in 5V bias t on the RSPdx. So well, in fact that I wonder what the advantages/disadvantages of using it this way are?
I have more gain on this antenna than I do on my W6LVP. Higher noise floor (slightly) but also improved SNR. It appears to be a marvel of modern science. It does just fine attached to my wooden fence, about 6 feet high. I'm wondering if I should go to the trouble of attaching it to my Yaesu rotator, currently supporting the other loop about 20 feet up, to clear most obstacles. Would having two loops within several feet of each other cause issues?
I have more gain on this antenna than I do on my W6LVP. Higher noise floor (slightly) but also improved SNR. It appears to be a marvel of modern science. It does just fine attached to my wooden fence, about 6 feet high. I'm wondering if I should go to the trouble of attaching it to my Yaesu rotator, currently supporting the other loop about 20 feet up, to clear most obstacles. Would having two loops within several feet of each other cause issues?
Hi Dominic,
It will work powered by the bias tee in the SDRPlay but the IP3 performance will be down compared to when powered at 12 V with the Bias Tee unit.
For casual listening with the SDRPlay it will be fine. For use with higher performance receivers it's better to use the Bias Tee unit with a 12 V supply.
Mounting any antenna above the local clutter makes a big difference to it's performance.
You should be OK mounting loop antennas fairly close together.
Recently one of our customers has reported back on tests where he mounted a v4 loop antenna in his roof space with a tuned magnetic loop for transmitting running 30 W only 1.5 m or 5 ft away. The nulls of each loop face each other and from what I can recall without checking back through the emails he can receive on the 17 m band while transmitting on 20 m.
Regards,
Chris
It will work powered by the bias tee in the SDRPlay but the IP3 performance will be down compared to when powered at 12 V with the Bias Tee unit.
For casual listening with the SDRPlay it will be fine. For use with higher performance receivers it's better to use the Bias Tee unit with a 12 V supply.
Mounting any antenna above the local clutter makes a big difference to it's performance.
You should be OK mounting loop antennas fairly close together.
Recently one of our customers has reported back on tests where he mounted a v4 loop antenna in his roof space with a tuned magnetic loop for transmitting running 30 W only 1.5 m or 5 ft away. The nulls of each loop face each other and from what I can recall without checking back through the emails he can receive on the 17 m band while transmitting on 20 m.
Regards,
Chris