I agree with Roger.
I have two huge BC station signals at my QTH, fortunately one (50KW on 1550 kHz,
-3dBd on my vertical) is daytime only. The other on 1330 kHz is just as strong
but reduces power at night. My K3 and K3S are immune.
But I bought one of those toy radios, an Airspy HF Discovery, that was claimed
to be filtered and bulletproof. Not so. After providing screen shots on the
Airspy group.io I was moderated right off. A cheep HPF from RTL-SDR fixes the
issue at the expense of BC reception as does a 20dB pad. This last point
reinforces Roger's point that you might not need much attenuation to solve the
problem.
I can say that impedance measurements with low grade antenna analyzers can be
problematic. My N2PK, DG8SAQ and FA-VA5 vector analyzers are all up to the task.
Wes N7WS
On 4/17/2020 4:19 PM, Roger Kennedy wrote:
$180 for a receiver filter? That's absurd !
I also wouldn't want one that attenuates 160m too.
Is the station you are having problems with actually above 1.6MHz ? If not,
you don't need a filter that starts attenuating within Top Band, like that
one does.
And you might need hardly any attenuation to stop the cross-mod you are
getting.
Personally, if it's just from one station, I would just put a simple
parallel tuned ciruit in series, tuned to that frequency . . . that would
probably cure the problem. And that would just cost you less than $1 !
(By the way, if you now have stations broadcasting between 1.6 and 1.7 MHz,
how does anyone pick them up? I don't know any broadcast radios that go
above 1.6 !)
Roger G3YRO
__________________________________________________________________
Thank you all for your recommendations. Leaning towards this filter below.
Any objections before I pull the trigger?
http://kiwa-electronics.com/bcb-rejection-filter-20.html
73,
Ed NI6S/7Z1ES
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