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Reviews For: DUNESTAR 400-HPF

Category: Filters, RF: bandpass, duplexer, lowpass, highpass, RFI/EMI

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Review Summary For : DUNESTAR 400-HPF
Reviews: 7MSRP: $114
Description:
Highpass filter (1.8 MHz and up)
Product is in production
More Info: https://www.dunestar.com/product/highpass-filter-1-8mhz-and-up/
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
1474.6
WB0GAZ Rating: 2023-03-04
Provides about 10 dB reduction on nearby 1690 kHz AM BC Time Owned: more than 12 months.
My AM BC situation is borderline for the Dunestar 400-HPF; the BC station is at least 10 kW, about 2 miles away, on 1690 kHz, and my transceiver has direct conversion architecture so it's already susceptible to AM BC.

My 20M wire loop (in plane with the BC antennas) shows about +10 dBm/10mW coming out of the coax in the shack. The Dunestar 400-HPF reduces this by 10 dB or so. The Dunestar product page doesn't include a sweep.

I'd suggest Dunestar include S21 (through) sweeps and minimum specs in their filter product pages, and perhaps develop a version that can separate 1.7 MHz AM BC from 1.8 MHz ham band.
AA4MB Rating: 2015-12-21
Amazing filter Time Owned: 0 to 3 months.

Here's my story: I had significant broadcast interference from a broadcast station a few miles away. It was pretty easily identified and only happened during the daytime, when their 50,000 watt blowtorch was in operation; at night, they dropped power levels and I had no issues at all. I was experiencing interference on 40 meters which didn't exactly make it unusable during the daytime, but the interference was running at an S9 constantly and it made for bad operating experiences. After plugging in the Dunestar 400-HPF, it was like magic. ALL interference drops out and I'm seeing a more reasonable S2 to S3 noise level on 40 meters. Life is good again for daytime HF!

(I was also experiencing the issue on 80/75 and 160 meters, but my use of those bands only takes place after 6 pm at the earliest. Testing the filter response on both of those bands reveals a similar miracle cure for the BCB interference)

It's hard to find something that has quality construction for a reasonable price nowadays, and the Dunestar filter restores my faith in product advertisement reflecting actual performance. No way could I give this product only an 'OK' for working so well. Thank you Dunestar, for saving daytime 40 meter operating at my QTH!
VE2DC Rating: 2010-01-31
Excellent Time Owned: more than 12 months.
This is an update and corrections. AFAIK it is still in available. It has excellent rejection. It will solve your BCB issues if the problem is front-end overload. It can not solve problems caused by BCB harmonics generated (typically by diodes or connections acting as diodes) prior to the filter. I have encountered this with diodes used in wattmeters, loose antenna or coax hardware and even a very expensive HF power amp. These problems can only be solved at the source.

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Earlier 5-star review posted by VE2DC on 2003-05-09

Have had trouble for years with a couple of local broadcast stations. This cleaned up the intermod on 80/160 nicely. BTW, if I hook up a 12V bulb directly across my 160/80 antenna's feedline... it lights up to nearly full brilliance... and pulses with the modulation of the closer local broadcaster...
VE4AMN Rating: 2008-10-30
Cleans up 160 and 80 Time Owned: more than 12 months.
This does not eliminate all the BCB on the low bands, but it is a very worthwhile addition to the shack. The two low bands are much quieter. I attached it to the back of my Kenwood AT 200 tuner and it makes for an unobstrusive and effective package. Recommended and a decent price.
WA1SEO Rating: 2008-02-15
Works as expected,Great! Time Owned: 0 to 3 months.
I live in relatively close proximity of several broadcast stations. My ICOM 706MK2G was virtually useless on 160 unless I used an external attenuator, but then the signals were too weak to copy. My Orion 2 had an issue also, although I could still operate with 12dB of attenutation.

I took the advice of a friend and ordered the Dunestar 400-HPF without even investigating it. When I received it, the first thing I did was look at the response on my network analyzer from 500KHz thru 1.8MHz...it looked like the perfect solution. I connected it to each radio with a bypass switch to make a before/after comparison. I can now use the preamp in each radio on 160! I'm very pleased with this product.

Mike, WA1SEO
K4SXT Rating: 2000-06-04
Does the job Time Owned: more than 12 months.
The Dunestar 400 HPF does what it is supposed to do - the cutoff is very sharp starting just below 1.8 mhz. Without the filter I would not have been able to operate on 160 meters from this QTH near a broadcast station in Guam. Many thanks to Dunestar - KH2/K4SXT
N.A. Rating: 1999-10-25
The Dunestar 400 HPF cures IMD in the IC-756 Time Owned: unknown months.
I was having bad IMD on 160 meters in my ICOM 756 until I got a Dunestar 400-HPF (I have a 50KW broadcast station 1/2 mile from my house) -- with the filter in line the IMD is gone. My receive capability on 160 is greatly improved.