CW Test Results on C3 Electronics LLC
80M Digital Bandpass Filter
80M Digital Bandpass CW Test
June 1, 2025
“I received the Ultimate Package shipment today, it is a very nice package!
After seeing that the labels on the product say maximum power on SSB is 100 watts, I wanted to verify that the filters can also handle 100 watts on CW, as that is where I intend to use them.
73, Roger KF9D
Hi Carol,
I have taken your advice and tested the 80 meter digital filter on CW this morning. Here's a screenshot of the filter response before the test."
Photo Provided By: Roger KF9D
Test conditions:
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Room Temperature 70 degrees (21 deg C),
Filter suspended in free space with airflow to all surfaces and
directly attached to a commercial dummy load, radio power out set to 100 watts,
thermocouple glued to the top surface of the filter case.
Photos Provided By: Roger KF9D
CW Setup:
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“I set up the contest logging software to call CQ at 26 wpm and repeat every 4 seconds for one hour straight, similar to a serious field day effort.
Results:
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I did not notice any change in the SWR on the radio display during the test.
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The filter became warm to the touch after a few minutes, but not hot.
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After 30 minutes the filter top lid temperature had risen by 16 degrees C (to 99 deg F).
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After the one hour test, the filter top lid had risen by 17 degrees C total, so no real change from 30 minutes.
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Ten minutes after the test concluded the top lid temperature had fallen by 10 degrees C.
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Immediately following the test I again did a filter response with the Nano VNA as shown below.”
Photo & Test Result Comments Provided By: Roger KF9D
Conclusion:
The image shows no shift in the filter characteristics from what they were initially. My conclusion based on the single band test is that these filters should perform fine on cw at field day, as long as they are not in direct sunlight.
Thanks for offering a fine product at a reasonable price.
Find out how our bandpass filter worked at a POTA (Parks on the Air) activation on July 9th, 2024.
In the video, you will see the close proximity of antennas and transmitters used with our 20M bandpass filter that KD9QXL used and made the most contacts during the day with. His son used my callsign W9PIO on 10M with our 10M bandpass filter while I monitored and took a video of our POTA activation. 10M was slow, but 20M received a lot of contacts.
No RF interference happened to either operator while transmitting on either the 857D or 991A. Antennas where no more than one car length apart.
Watch the video and then Shop Our Products.
Here is another video demonstration of W9PIO and N9NAV working out of a basement room with a 857D Yaesu and a 710 Yaesu in very close proximity. Our antennas are less than 5 feet apart in our backyard.
Hear Our Performance In This Video
POTA activation at Tomorrow River State Trail in Ogdensburg, WI.
POTA Park # US-9815
Competitor Comparison
C3 Electronics LLC
20M Bandpass Filter
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SWR 1.028
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Inserrtion Loss 0.69 dB
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Test Frequency 14.320 MHz
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Company began in May 2024 and has several bandpass filters in stock ready to ship on these bands:
10 M - 15M - 17 M
20M - 40M - 60M - 80M
Dunestar 20M Filter
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SWR 1.286
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Insertion Loss 3.35 dB
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Test Frequency 14.040 MHz
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Company closure in 2023 (See Note below)
