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write your own review of the INRAD Roofing filter Icom Pro II.
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K1KP
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Rating: 5/5
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Nov 26, 2007 05:54
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Follow-up: It WORKS
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Time owned: 3 to 6 months
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Just a follow-up to my previous review:
I used my INRAD-modified 756Pro2 in the CQWW CW contest this weekend. I took a few moments out of the contest to see what difference the roofing filter made. Listening to strong CW signals at the bottom of 40 meters using a 2 element beam, there was definite and significant improvement in IMD. Specifically, with the filter out there were lots of noticable chirps and tweets; with the filter in they were completely eliminated.
You might not notice the difference in other than contest conditions, or with less effective antennas like wires and dipoles. However, if you are a contester on a budget, the addition of a $200 upgrade to a radio that is available for $1500 on the used market will get you all the performance of the latest $3K rigs.
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KN7T
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Rating: 3/5
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Nov 14, 2007 13:35
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Not Impressed
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Time owned: 0 to 3 months
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I purchased the INRAD roofing filter for the PRO II hoping that it would perform as marvelous as the similar filter for the IC-765, which I also have (see my review on that filter). The installation instructions are well-written but the installation itself is NOT for the faint of heart. If you aren't comfortable with disassembling circuit cards, cutting circuit traces and soldering in very tight spots, I would highly recommend that you have someone else install the filter for you. Once installed, I noticed the same bandscope skew that was described in one of the earlier reviews. I called INRAD and asked them about it and they told me that they were developing a modification for the filter to eliminate the problem. INRAD has now shipped the modification kits to those who previously purchased the roofing filter - it is necessary that you remove the filter from the radio to install the mod kit. The modification did smooth out the scope display somewhat but it still isn't perfect. I don't consider it to be a problem, however, as the bandscope has limited usefulness in my opinion. Subsequent to the filter installation, it didn't seem to me that the filter was really doing anything - I didn't notice any major difference when operating in crowded band conditions with lots of close-in strong signals. The effect of the similar filter in the IC-765 was much more pronounced - and that may be due to the fact that the DSP and updated technology in the PRO II receiver already makes it a good performer. I thought perhaps I had mis-installed the filter or it was somehow being bypassed but further checking revealed that it was, in fact, installed properly and was operating. To be fair, I think my experience with the filter in the 765 had my expectations very high for the PRO II version so I felt a little letdown when it was all said and done. The "real world" performance increase with the filter installed appears to be minimal at best. With a pricetag of $200, I think my money might have been better spent on something else.
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W5VIN
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Rating: 5/5
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Aug 21, 2007 15:22
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Works Great
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Time owned: 6 to 12 months
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George, W2VJN and I incorporated an INRAD roofing filter into my IC-756 Pro2. I placed it into the first location we had picked and then sent the rig to George for testing. After dismal test results it was determined to move the filter farther upstream which George did with results that are published on dk.mods. I do not have the same problem as the previous post by NS1L so I'm suspecting there may be an error in his install. I have swept mine with a wide band noise generator and it is linear across the spectrum. It is a worthwhile mod which really changes the rigs IMDDR test results.
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NS1L
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Rating: 5/5
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Aug 19, 2007 08:16
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Greatly Improved IMD & BDR
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Time owned: 0 to 3 months
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I had the INRAD Roofing filter installed and found that the improvement was dramatic. I have
an FT1000MP MK V with an INRAD Roofing filter for comparison. Before the Pro II roofing installtion, I compared the two Radios for IMD and BDR. The MK V was just barely ahead of the Pro II. After installation, the Pro II was way
ahead of the MK V in both IMD and BDR. I was very please to have the Pro II with Roofing filter installed. BUT..... After testing both
radios on CW.... I went to SSB and turned on the Bandscope on the Pro II. I first noticed that the
bandscope now has a skewed look. It no longer has the nice constant level across the entire band. There is a double bump above and below the center of the bandscope. The lower bump at about 5 KHz lower is about 10db Higher in reading on the scope. While the bump that is about 4 to 5 KHz Higher is about 4 to 6db Higher than at the center of the bandscope. I have had the filter installed just a few days, I do not like the skewed bandscope, but the improvement in the IMD & BDR may or may not be worth the skewed bandscope??? I am sure that the skewed looks is due to the 70 MHz Roofing filter narrowing the bandwidth of the following I.F.'s and the bandscope is farther down the chain and this is the trade off you may have to accept, if you install this filter. 73 de Jim NS1L
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