When I was in Guam I used a Dunestar 400hpf with good results
Gus K4SXT
> On Jul 29, 2019, at 14:08, Don Kirk <wd8dsb@gmail.com> wrote:
>
> Had a similar problem at Field Day a few years ago with WJR (50,000 watt
> station). Noticed the problem was not present when antenna tuner was
> inline. Many modern rigs have broadband front ends which provide very
> little attenuation to out of band signals, and just the addition of an
> antenna tuner solved our problem (the tuner provided very good out of band
> filtering).
>
> Don (wd8dsb)
>
>> On Mon, Jul 29, 2019 at 1:34 PM Grant Saviers <grants2@pacbell.net> wrote:
>>
>> Here is what I used when I had the same problem 50kw line of sight 4
>> miles 1MHz. Expensive, but worked very well.
>> http://herostechnology.co.uk/pages/RF_Filters.html
>>
>> Having the filter between rig and amp worked fine for me. 200w rating
>> for the Heros.
>>
>> My power line had ~1v of RF, so ebay Sprague 20 amp line filters were on
>> the shack 120v supply and 240v amp also. Plus 240-31 ferrites on the
>> green wires.
>>
>> It will take some proper ferrite chokes to kill the RF on the coax
>> shields and any other control cables. Plus a good ground system.
>>
>> IMO, Dunestars have poor reliability for their HF bandpass filters when
>> on DXpeditions.
>>
>> I always like to see the VNA sweep in the ad and then use my VNWA to
>> test whatever I buy since the tuning is hand optimized. A couple went
>> back for retuning.
>>
>> K9YC has some comments re BCB rejection for 6 band filter sets. That is
>> another alternative.
>> http://audiosystemsgroup.com/BandpassFilterSurvey.pdf
>>
>> Grant KZ1W
>>
>>> On 7/29/2019 9:29 AM, Mark K3MSB wrote:
>>> A friend of mine in our local radio club sent me the following email
>>>
>>> "I'm 6/10's of a mile from an AM 910 KHz. transmitter. They operate with
>> 5k
>>> daytime and 2k at night.
>>>
>>> They're S9+45db on 160 meters with clear audio and S9+35db on 80 meters.
>>> have an inverted "V" resonant at 3.715 MHz. orientated east-west, towards
>>> their reflector tower."
>>>
>>> The station is willing to pay for a filter for my friends station, and
>> he
>>> has looked at notch and band pass filters but has concerns.
>>>
>>> I recommended he look at transmit high pass filters to knock out signals
>>> below 1.8 Mhz and provided him with various links:
>>>
>>> https://www.dunestar.com/store/160-Meter-Highpass-Filter-pid-8.html
>>>
>>> http://www.kf7p.com/KF7P/Morgan_Filters.html
>>>
>>>
>> https://www.dxengineering.com/search/part-type/transmit-high-pass-filters/product-line/dlw-associates-am-broadcast-band-brick-wall-high-pass-filters?autoview=SKU&sortby=Default&sortorder=Default
>>>
>>> I have no practical experience with any of these filters and was
>> wondering
>>> what the TB Gang thought.
>>>
>>> He would prefer one that handled 1.5 KW but I told him he may have to
>>> settle for 200W.
>>>
>>> He prefers an "out of the box" solution.
>>>
>>> Thanks
>>>
>>> Mark K3MSB
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