When I was in Guam I used a Dunestar 400hpf with good results Gus K4SXT
> On Jul 29, 2019, at 14:08, Don Kirk <[email protected]> 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 <[email protected]> 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 >>> _________________ >>> Searchable Archives: http://www.contesting.com/_topband - Topband >> Reflector >>> >> _________________ >> Searchable Archives: http://www.contesting.com/_topband - Topband >> Reflector >> > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
