[TowerTalk] Broadcast Band Filter

[Jeff Blaine]

If the mixing product is internal to the rig, the filter will help.

What John is talking about is rectification/mixing occurring outside 
somewhere (rusted metal contact, something weird but not infrequent) so 
that the antenna is picking up an 80m signal.  You hear the something, 
but in this case the interference is "in band" and thus the filter won't 
help at all.

The easy way to check the location (in the rig or external) is to dial 
in some attenuation.  If the interference product drops faster than the 
amount of attenuation (e.g. 6 db of attenuation results in the 
interference dropping by around 20 db), then it's a problem inside the 
rig (overload) and the filter will help.  If the interference drops by 
the same amount as the attenuation, then it's outside the rig somewhere 
and the hunt for that as well as mitigation is a project...

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 3/27/20 1:11 PM, David Gilbert wrote:
>
> I don't understand your comment.  A filter is a filter.  Assuming 
> we're talking a band reject filter, if the filter is between the 
> source of the AM signal and the rig, even if the source is due to 
> rectification, the filter should still do its job.  Why would it not?
>
> 73,
> Dave   AB7E
>
>
>
>
> On 3/27/2020 5:43 AM, john at kk9a.com wrote:
>> Probably Array Solutions, DX Engineering and maybe VA6AM have 
>> broadcast filters however if there is rectification occurring they 
>> will likely not help. At my station in Chicagoland I could hear a mix 
>> of two AM broadcast stations on my 80m TX antenna which was quite 
>> annoying at times. I never tried a specialized filter because I did 
>> not feel that it was a RX overload issue.
>>
>> John KK9A
>>
>>
>> Mike Ryan mryan001 wrote:
>>
>>
>> I remember someone recommending a brick wall AM broadcast band filter 
>> some
>> months back.  Was a little on the expensive side but.if it works. Anyone
>> recall that thread and the name and/or contact for the manufacturer or
>> dealer?  Thanks.   - Mike
>>
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