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| Reviews Summary for INRAD Roofing Filter ICOM Pro III |
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Reviews: 6
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Average rating: 4.2/5
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MSRP: $200
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Description: This roofing filter can help reduce the third order Intermodulation from multiple strong signals in the 2 to 20 kHz region either side of the tuned frequency. Please see our document titled "A Few Words About Roofing Filters" for more details.
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More info: http://www.inrad.net/product.php?productid=225
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write your own review of the INRAD Roofing Filter ICOM Pro III.
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KC3ET
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Rating: 5/5
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Jul 9, 2009 12:28
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Works Great
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Time owned: more than 12 months
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Hello
I promised that I would respond once I received my Icom 756 Pro III transceiver from Burghardt, for repair, and installation of the Inrad Roofing Filter. I received my transceiver at the very end of May. They replaced one SMT resistor that I had managed to burn up with my soldering iron, and installed the Inrad Roofing Filter. The Burghardt techs did a great job. It turns out the burned out resistor caused my ACC1 connector to not work. I hadn't realized that it wasn't working.
As far as the new filter, it works very well. I do notice that when turning the main tuning knob that the ssb and cw detection is more sharp than with the original filter. It definitely is detecting radio signals closer to the dialed frequency. I used to hear some splatter from strong stations on nearby frequencies with the original filter. I do not notice that problem as much as before. On cw, it is very sharp.
Is it worth it? In my opinion it is. The only thing that I would say is that it is not a kit for those who have average skills in kit building, like me. Removing that one blasted SMT resistor was near impossible for me. I could just barely see it with my eyes. I could see it with a 5x and 10x magnifier. If you want to do it yourself, you will need some sort of heavy magnification device, and a very sharp tipped soldering iron. :(
Well, I hope that this helps you.
73 de Chuck KC3ET
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KI9A
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Rating: 5/5
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May 1, 2009 14:45
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Great item
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Time owned: 3 to 6 months
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Inrad is correct that it is not for the normal ham to install. Mine was time consuming, but, during crowded band condx, it has proven to be very worthwhile mod.
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KC3ET
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Rating: 1/5
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Apr 28, 2009 19:15
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Have It Installed Professionally
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Time owned: months
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I recently purchased the 'Inrad IC756 Pro 3 Filter Mod'. Inrad is correct that the installation is not for the average radio amateur. I started the installation, but stopped when it came to the step in which I would have had to remove the R216 SMD resistor from the
RF-A board. I finally found R216 using a Jewelers Loop. It is very small. I also had to use quite a bit of soldering iron heat to get the center shield cover off of the RF-A board. Also, my preparation of the 2 RG174 cables that connect from the RF-A board and the Inrad filter, was not easy, as the cables kept breaking. At this point, I have packed my IC 756 Pro 3 and sent it out to Burghardt for repair and to install the filter. The Burghardt rep told me on the phone that they use a Microscope to work on both repairing the IC 756 Pro 3, and installing the Inrad filter mod for the IC756 Pro 3. I asked the rep at Burghardt to go over all of my work, and to check the IC756 Pro 3 for proper operation. Prior to shipment, I reassembled the IC756 Pro 3. It appeared to work properly, although I am not sure whether the sub receiver is working or not. I will post my results when I receive the IC756 Pro 3, with the Inrad filter installed, when I receive it from Burghardt.
For now, my advice, if you want that filter have it professionally installed. Inrad mentions several companies that can do the installation.
73
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EA3GEG
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Rating: 5/5
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Dec 25, 2008 09:34
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Very good
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Time owned: more than 12 months
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I installed INRAD filter on my pro III, and the results are very good, the noise and splatters for nears frequecys going down, signal about +25 dB, on 3 or 5 Khz up don't disturb now.
The instalation is a little dificulto, but with pacience don't any problem.
Grettings
Joan EA3GEG
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K8AC
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Rating: 4/5
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May 22, 2008 15:48
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Difficult installation - minor scope effects
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Time owned: 0 to 3 months
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I chose to install this roofing filter after experiencing the IMD problem during the CW SS in 2007. While I don't have any way to test the results (until next contest season), I trust the info provided by I1ODP regarding the measurements. If you're not confident of your ability to work with the tiniest of surface mount devices, you probably want to avoid doing the install yourself. You need to remove a resistor and connect a discrete capacitor and resistor to the pads left after the removal, and you'll need some good magnification to carry that out. Mechanical work includes the removal of a shield can from the board, drilling two small holes in it and attaching two small coax cables to the shield. The filter board is completely assembled and it is placed in an open space just to the right of center behind the front panel display. The board just sits in the space and can move around if you happen to ship your Pro III, so if you plan to do that you might consider forcing a piece of foam plastic between the board and the frame to hold it in place.
I had heard that the filter had some effect on the spectrum scope display, but observed only a minor effect on signals. At a point approximately 3.3 KHz on each side of the center frequency, I found that the displayed signal peaked about 3 dB over a small range and I determined that by tuning across the calibrator signal while watching the signal height with the vertical scale. The effect isn't noticeable unless you're looking for it with the calibrator or other stable signal source.
The filter reduces the bandwidth enough to affect the fidelity of AM broadcast signals as you'd expect, but it's in the signal path for the main receiver only. If you want to listen to AM with the same fidelity as before, you can use the subreceiver in dual watch mode and adjust the balance control so you don't hear the main receiver.
My rating of 4 considers the difficulty (and high risk) of the installation and the fact that the filter board is not secured in the mounting space. I would not recommend the installation unless you are bothered by the IMD problems of the stock receiver.
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I1ODP
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Rating: 5/5
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Feb 24, 2008 10:22
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A great performer
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Time owned: 0 to 3 months
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I just measured my Pro III with Inrad roofing filter (nominal 3kHz BW) :
Noise Floor -135 dBm
MDS -132 dBm
Dynamic Range with
2 interfering signals spaced 5kHZ -------------> 95 dB (9+35 on the Smeter) about
2 interfering signals spaced 4kHZ -------------> 92 dB (9+30 on the Smeter) "
2 interfering signals spaced 3kHZ -------------> 82 dB (9+20 on the Smeter) "
Without the roofing filter I measured years ago my Pro III see
http://www.ab4oj.com/icom/ic756pro3/i1odp.html
and close-in Dynamic Range results where :
2 interfering signals spaced 4,4 kHZ -------------> about 80 dB.
Conclusion:
Using narrow VHF roofing filters you improve your Pro III DR (2 sigs spaced 4 kHz) by more than 12 dB .
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