Topband: BCB Filter - final selection

[Wes]

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
>
> _________________
> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector