ALA1530+ with 25kw AM Broadcast station a mile away

[WM7C]

ALA1530S+ with 25kw AM Broadcast station a mile away

I guess I never noticed that the KNZR towers down the street were pushing 25,000 watts in the day. The 10,000 watts at night are not as noticeable. With the Wellbrook loop, I heard KNZR on my KX3 on every band at S9+, all the way up past 28 MHz. I had just bought a PX3 too. The ALA1530+ is the only antenna I am able to use here right now, and am an SWL when at home. I bought an FTDX1200, which also hears the AM broadcast station across most bands. On their frenquency, they are over 60dB over S9.

Is anyone using a filter with success? I emailed Jack at Cliftonlabs, but he hasn't replied with pricing yet. I don't care if I lose 160 meters.

 

[nanZor]

PAR electronics makes a good AM band filter, among others. I'd suggest the switchable BCST-HPF: (rx only!)

http://www.parelectronics.com/swl-filters.php

Problem is, at 25kw, even this might not be enough if you have a lot of common-mode current just blowing through. (current on outside of cabling, etc). Ferrites would help here, both at the rig and at the loop's amp in case it too is getting blown away.

I would start with the PAR am-broadcast band filter. Then, additional testing like running solely from a large battery with very short leads, and perhaps using ferrites on the coax and power leads to the loop.

 

[AA6IO]

I have the same situation here with SWL listening using a Pixel loop with KFI AM, 50,000 watts, 2 miles away. With my Perseus and ELAD FDM-S2, usually 10 db of attenuation will allow me to listen to most things. I have PAR filters to block AM for both long wave below 550 and above 1700. They work great. KFI is 0 dbm at my QTH (1 mw to my attenna input). Put the high-pass filter in, no problem listening to 160 and above.
Steve AA6IO

 

[WM7C]

Thank you both for replying. I ordered the Par BCST-HPF and am looking for ferrite beads to snap around my LMR240.

 

[SCPD]

I have a similar situation here. I had an ICE BCB filter which did OK but it was more effective at the lower end of the AM band versus the top end. My biggest AM offender is at 1540 Mhz and so Jack customized his Z10023 HPF filter for my specific situation. My cut-off is slightly into the 160M band but it's like 1850khz so it doesn't bother me at all.

Z10023A Elliptic High Pass Filter


Here's a screenshot of HFSPAN showing the DC to 10 Mhz with the filter:

Here's a screenshot (at the same time of day) without any filter:

 

[WM7C]

I hope I get similar results from the Par BCST-HPF.

 

[ka3jjz]

Did you look at the response curve for that filter? It would give you a clue - and you could ask Dale to retune the filter, if needed. He's very responsive like that...just click on the pic of the filter, and you will get a response plot. But from what I can see, you won't need to ask for retuning, even as high as 1560 khz Mike

 

[WM7C]

Did you look at the response curve for that filter? It would give you a clue - and you could ask Dale to retune the filter, if needed. He's very responsive like that...Mike

This is it.

 

[SCPD]

If you have a good station ground then be sure to ground the filter. You'll only see maximum performance if it's grounded.

If I had a proper station ground then I'd probably see better numbers.