What does BCI sound like? It is the hetrodynes you hear on 1810, 20, 30, etc?
Sent from my iPad
> On Jan 30, 2022, at 9:51 PM, Joe Subich, W4TV <lists@subich.com> wrote:
>
>
> Jack had some excellent information on a HPF that incorporated two
> or three notches that made a significant difference in rejection
> of specific stations in the higher portion of the AM Band. As I
> recall, the difference could be going from 20-30 dB above 1200 KHz
> on a simple HPF to 50 or 60 dB at the cost of flatness in the reject
> region. The ability to knock down individual stations was generally
> worth the trade off.
>
> I hope I saved a copy of that information somewhere as I will certainly
> need it with a couple stations between 1000 and 1400 KHz that put >
> 10 dBm on my 160/80 antenna (I can measure it with a sensitive wattmeter
> and dummy load).
>
> 73,
>
> ... Joe, W4TV
>
>
>> On 2022-01-30 7:41 PM, Tim Duffy wrote:
>> DX Engineering makes the Clifton Labs AM receive reject filter:
>> https://www.dxengineering.com/parts/dxe-z10020-pm
>> DX Engineering also carries the excellent DLW filter:
>> https://www.dxengineering.com/parts/dlw-fl1718
>> 73
>> Tim K3LR @ DX Engineering
>> -----Original Message-----
>> From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Joe
>> Subich, W4TV
>> Sent: Sunday, January 30, 2022 6:54 PM
>> To: towertalk@contesting.com
>> Subject: Re: [TowerTalk] Broadcast Band AM Transmiiter Intererence on 160M
>>> On 2022-01-30 6:09 PM, Jim Brown wrote:
>>> Unfortunately I didn't have enough cursors to put one in the AM
>>> band, but an eyeball guestimate is that the better ones will get you
>>> 15-20 dB at 1420. That report includes measurement for a vintage ICE
>>> BCB, which is in that range. As I understand it, Morgan took over
>>> that line. >
>> > The trap that Jim Lux suggested would probably go a lot lower.
>> Jack at Clifton Labs had some designs that replaced the inductor(s)
>> in HPF designs with series tuned traps for specific 'problem"
>> frequencies. Unfortunately Jack is an SK and DX Engineering which
>> took over some of his designs seems to have dumped most of Jack's
>> work and all of the information on his web site.
>> 73,
>> ... Joe, W4TV
>>> On 2022-01-30 6:09 PM, Jim Brown wrote:
>>> On 1/30/2022 1:57 PM, Mike Ryan wrote:
>>>> By FAR my greatest offender is at 1420AM which is less than one
>>>> mile from my qth.
>>>
>>> If you can kill it with a BPF or HPF, they're not the offender, the
>>> preamp is. And with the problem station fairly high in the band, you'll
>>> want a BPF or HPF with pretty steep skirts. Best bet is to study
>>> published curves for stuff from DX Engineering, WX0B, and the filter
>>> mfrs themselves. I remember looking a year or so ago and the state of
>>> the art seemed to be in the range of 40 dB fairly high in the band.
>>>
>>> Also, the better BPF sets made for contesting have pretty good
>>> attenuation on the AM BC band. At the end of this report is a link to my
>>> measured data on those that I owned or had loaned to me for measurement.
>>>
>>> The report: http://k9yc.com/BandpassFilterSurvey.pdf
>>> The data: http://audiosystemsgroup.com/BandpassFilterData.htm
>>>
>>> A few years ago, I acquired a pair of used Hamation FilterMax-IV sets
>>> that measured quite well, but I don't think I saved the data. TXBPF sets
>>> are in my SO2R station, and the Hamation units are on the rig side of
>>> switching for my RX antennas.
>>>
>>> Unfortunately I didn't have enough cursors to put one in the AM band,
>>> but an eyeball guestimate is that the better ones will get you 15-20 dB
>>> at 1420. That report includes measurement for a vintage ICE BCB, which
>>> is in that range. As I understand it, Morgan took over that line.
>>>
>>> The trap that Jim Lux suggested would probably go a lot lower.
>>>
>>> 73, Jim K9YC
>
>
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