Flag/Pennant LOOP HF Antenna

[ILSAPP]

I'd like to know if anyone had this particular antenna from a well-known russian ham and, if yes, how does it compare with a dipole, inverted vee, and others HF antennas. Also, even that people who do not have it I'd appreciate to come here and give your opinions about this antenna config for SWL listening.

I'm looking for another RX-only antenna (switching antennas in the future) only to cover mainly from 3 to 15MHz for SSB listening.

Link here: https://www.ebay.com/itm/Flag-Penna...AM-RADIO-SWL-50-Ohm-with-Preamp-/201553084711


Thank you!

 

[ka3jjz]

Just on its face, the seller being Russian and the time delay, proceed with extreme caution...this is fleaBay, after all....

Anyway I question the use of a preamp on this antenna. With 72 foot of wire (which you supply), that will be more than enough to feed any modern receiver. In fact, if you're in an urban area with lots of MW and FM stations, the preamp just might cause more issues than it solves.

I think something smells here...Mike

 

[ILSAPP]

Thank you for the quick reply and your valuable input (as always) KA3JJZ.
There are none MW stations nearby here but FM stations yes and many of them pretty close. In fact I'm using a FM notch filter in VHF radios listening and even with it many FM stations are still strong enough.

Just on its face, the seller being Russian and the time delay, proceed with extreme caution...this is fleaBay, after all....

Anyway I question the use of a preamp on this antenna. With 72 foot of wire (which you supply), that will be more than enough to feed any modern receiver. In fact, if you're in an urban area with lots of MW and FM stations, the preamp just might cause more issues than it solves.

I think something smells here...Mike

 

[ka3jjz]

ILS the mode you are using has nothing to do with the antenna. Be a bit more specific about your situation and there's a lot of folks here that can make recommendations. How much space do you have to work with? Hertzian's log antenna might be a good answer if you need to contend with HOA nazis. See the thread in this forum on this. So might loops like the W6LVP - there are many other possibilities

Mike

 

[ILSAPP]

I have room for large antennas and I have available a 12m spiderbeam pole and another smaller masts.I can use 40m of wire easily in my property.
I really want to get the best performance of the SWL for those particular range of frequencies.
I've been looking also to PAR EF-SWL End Fed and W6LVP/ALA1530 loops due to their great reputation and low noise performance. But of course I wonder if I can get about the same performance with much less money spent.

 

[ka3jjz]

Before you look to getting better antennas, look to clean up your FM BCI first. Why? Because if you are receiving interference on your VHF radios, there's a decent chance that you might introduce additional issues to your HF gear with better antennas.

You say you're using a notch filter; they're good for only a narrow range of frequencies. Likely as not a filter such as this is more likely to help resolve the issue...

VHF-FM Broadcast Filters | PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts

Both the W6VLP and Wellbrook could be turned to point away from the FM stations, but if they are relatively scattered in direction from where you are, they might not help much.

Time to do some cleanup on this end before you end up introducing more issues with better antennas. Also any unshielded cables - even power cords - can act as antennas in extreme cases. Chasing this stuff down is not easy, but the results will be a cleaner environment for you to listen.

Mike

 

[ILSAPP]

I have attached a picture of the FM notch filter I'm using for the VHF. It has almost 80dB attenuation on the middle of FM band. I've never tried using the filter on the HF SMA port of the radio, just on VHF.

I've successfully build mag loop antennas with the manual tuning variable capacitor. However since I now need to use the radio remotely I have to use a different approach. Active loops are a possibility of course but since there are many designs out there I don't know which one will probably be a best bet for my needs.

 

[ka3jjz]

With that depth you shouldn't be getting any FM BCI. That strongly suggests that something else is happening here.

One thing I did notice is that your notch depth at 88 and 108 Mhz isn't nearly as good as at 98 Mhz. If the other interfering stations are in the poorer sections of the notch, then if they're strong enough, they would break through. Have you taken a survey of the FM stations that are causing you grief and see what frequencies they're on?

Mike

 

[ka3jjz]

Here is an example - I don't actually have this filter - of a FM bandstop filter with around 50db of attenuation across the band. While you couldn't use it on a transmitter, it would work just fine on a scanner, and likely on a HF receiver as well...

https://www.rtl-sdr.com/rtl-sdr-com-broadcast-fm-band-stop-filter-88-108-mhz-reject-now-for-sale/

Mike

 

[ILSAPP]

Many thanks for this great and valuable conversation KA3JJZ!
I'd like to add that I've never tried to use the FM notch filter in HF radio, just on VHF. So I really don't know if there will be any difference if I add it to the HF receiver.
Anyway, attached is a brief scan I did now from 1 to 300MHz at my location. As expected, it is clear the strong activity in FM band here...

Edit: Original image here: https://ufile.io/qgb4d

 

[ka3jjz]

I'm sure that a google search will turn up even better FM bandstop filters than this Chinese model - just make sure it has a response graph, or at least some attenuation statistics to make sure it will do what you want. Evidently you have other FM stations besides the one the notch hits that are giving you fits. A quality bandstop filter will nail the entire band

Mike