Nice report Jim! Data is given for ham band rejection but folks are not
going to find data for 41M and 49M shortwave band rejection.
Barry N1EU
On Tue, Sep 13, 2016 at 1:47 PM, Jim Brown <k9yc@audiosystemsgroup.com>
wrote:
> Several years ago, I measured a half dozen or so bandpass filter sets that
> I was able to borrow for NCCC members, and some that I owned. I wrote up a
> report, that was published in the National Contest Journal and the NCCC
> newsletter, "The Jug." That report, with links to the actual data for each
> filter on each band, is on my website. http://k9yc.com/BandpassFilter
> Survey.pdf The filter sets I tested were ICE, Dunestar, W3NQN sold by
> Array Solutions, and the very nice TXBPF set designed by Bob Henderson,
> 5B4AGN, based on a W3NQN design, and for which Bob did several group
> purchases. In addition, Bob sent me data that he measured on 4O3A filters
> rated for use on power amp outputs, and that data is in the report.
>
> 73, Jim K9YC
>
>
> On Tue,9/13/2016 1:17 AM, shristov wrote:
>
>> "rick@dj0ip.de" <Rick@DJ0IP.de> wrote:
>>
>> However the Dunestar SPECS on their web site claim 40dB band-to-band
>>> rejection. I was just quoting the specs.
>>> http://www.dunestar.com/store/Single-Band-Bandpass-Filters-pid-4.html
>>>
>>
>> Hi Rick,
>>
>>
>> that's what I had in mind.
>> Taking the 7 MHz filter as an example,
>> there is 40 dB attenuation on ~3.5 MHz.
>>
>> But on 6 MHz the attenuation is practically nil.
>>
>> Your preselector is the right tool for the job.
>> But it's receive-only, given the 7.5 dB passband attenuation.
>>
>> Dunestar etc filters must have a much wider passband
>> in order to achieve low enough passband attenuation,
>> making them suitable for transmitting.
>>
>>
>> Best 73,
>>
>> Sinisa YT1NT, VE3EA
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>>
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