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Reviews For: International Radio (Inrad) Roofing Filters

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

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Review Summary For : International Radio (Inrad) Roofing Filters
Reviews: 46MSRP: 175-200
Description:
Roofing filter mods for Yaesu FT-1000MP Series and FT-1000/D, Icom IC-756Pro/2/3, Icom IC-765/775/781, Ten-Tec Omni VI, Kenwood TS- 850/930/950 and other radios to improve close in dynamic range. Email: sales@inrad.net
Product is in production
More Info: http://www.inrad.net/
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00464.8
VR2BG Rating: 2006-02-11
Chalk 'n cheese! Time Owned: 0 to 3 months.
I have the temporary misfortune of having VR2B IARU/NCDXF beacon about 200m away, line-of-sight from my kitchen window.

Am writing this during CQ WPX RTTY contest. I'm on 14103 kc & although I can tell when VR2B transmits, I can actually work stuff now when it's on.

Spent more time pulling IC-765 from station console than fitting the filter itself.
W3MR Rating: 2006-02-03
Great Time Owned: 0 to 3 months.
Installed easily, works great. Just obtained a second FT-1000D and immediately ordered another INRAD roofing filter.
W4BQF Rating: 2005-10-06
Omni 6 Plus Filter Time Owned: 3 to 6 months.
The Omni 6 Plus is an excellent contest/DX radio. The 600hz Inrad roofing filter made it even better!
Normal QRN runs from 20 to 30 over here, turning on the Inrad filter, drops the QRN level to S-5 to S-7, without dropping the signal strength of the station your trying to copy. It clearly improves copying weak signals in a contest/DX pile up situation.
Installation is simple, instructions are clear and easy to follow. However, I modified my installation to be able to select/deselect the filter via the PROCessor button.
An exceedingly good addition to the Omni 6 Plus radio.

Tom - W4BQF
N0GV Rating: 2005-08-22
Very, Very Nice for FT-1000D Time Owned: 0 to 3 months.
Very good product -- the roofing filter just about kills any bleed over from stations over 2.5kHz off frequency -- blocking dynamic range seems to be better than 20dB improved over the stock FT-1000/D.

Given the high blocking dynamic range of the FT-1000 at 20kHz spacing the filter seems to bring this value in to a 5kHz spacing (2.5Khz above and below and signals just melt away). As an Electrical Engineering Professor with a great deal of experience in dealing with filters to reduce intermod and overload in very sensitive systems I can say that this filter modification has brought a great 20th century radio into the 21st century! If you need DSP then this is not the radio for you -- if you can do all your DSP in the Audio region (Computer) then this combination is amazing.

My best estimate is approximately 10-15 dB of IMD IP improvement and over 20dB improvement of the BDR at 5kHz tone spacing. 40m at night is now a possibility as IMD is no longer basting through the entire band.

This puts this radio with mod in the same league as the newer TenTec Orion and FT-9000 and most likely places it ahead of the (dare I say this for fear of igniting another flame war) ICOM IC-7800 in close-in dynamic range and close-in Blocking Dynamic range. I was very disappointed that ICOM saw fit to use a wide roofing filter in their IC-7800 when for 100-200$ more they could have put a narrow or several different roofing filters into the 7800 and made it really fabulous radio. BTW I suggested this to their engineers and tech reps prior to their release of the radio for production and was very disappointed that they did not follow my suggestion.

Grover Larkins
N0GV
8P6SH Rating: 2005-03-14
A must-do for contesters Time Owned: 3 to 6 months.
I confess that I wasn't sure just how effective this mod would be notwithstanding the theory of operation. What a surprise it's been to discover this mod makes a huge difference to me in the contests.

Here in the Caribbean, we have lots of strong signals to grapple with from the USA, EU and South America.

After installing the filter, life is good next to these strong signals.

Also, as a bonus, weak signal detection has been boosted a bit, so I now have a better time working the new multipliers I couldn't hear easily before.

Thanks George for a great mod that places an already great transceiver into one that's sure to save me the expense of a new contesting rig for years to come.

W6XR Rating: 2005-02-21
these filters work! Time Owned: 3 to 6 months.
I have been using the accessory roofing filters for several months on my FT1000MP Mark V and was not convinced they made a substantial differance until this last weekend's ARRL DX CW Contest. It was during the contest the filters performance became evident. I can't provide objective measurements but I know the QRM was much less an issue for me during the contest and using the 250 cycle Inrad filter too provided me with true single signal reality.

I embarrassed myself a few times with friends who I've contested with for 35 years when I opened up close to them and I never initially heard their presence on the bands. Listening on the other Mark V on the exact same frequency produced hisses and pops and other distortion not heard on the identical roofing filter equipped radio. It could be that you'll have roofing filters in your life for all serious radios used in the contest environment.

The purchase of these filters made a major performance increase for me and the "need" to spend 10K on a new radio has diminised!

NI0C Rating: 2005-01-19
Coming soon for TT Omni VI ! Time Owned: 0 to 3 months.
This review is based on my experience with a pre-production version of the roofing filter for the Ten Tec Omni VI (and VI+) radios. Check the
INRAD web-site for final specifications and availability of this product.

The circuit consists of a four-pole crystal filter (at 9 MHz) followed by a bipolar transistor amplifier. A miniature relay is used to switch the filter in and out. Miniature coaxial cables are provided to connect the circuit between the output of the RF board and the input of the 9 MHz IF board. (The cables just plug into the boards).

The board is mounted on the amplifier shield can near the radio's antenna jack, using standoff insulators with adhesive tape. Thus, the modification can be easily undone, if desired.

Power for the relay and the amplifier is taken from convenient points on the PBT board, and requires only one solder connection to this board.

The filter is switched in and out with the NAR1 and NAR2 buttons on the OMNI VI+, or with the NAR button on the Omni VI. A DIP switch is provided to choose the desired combination of roofing filter and 9 MHz narrow filter selected by the NAR switche(s).

I installed the CW version (600 Hz bandwidth) in my Omni VI. The installation was straightforward and I had the rig buttoned up again in just a couple of hours. The NAR switch on my Omni engages both the new roofing filter and a 400 Hz bandwidth IF filter (Inrad 753).

I do not have test equipment to measure the performance. However, before buttoning up the transceiver, I connected an antenna and used the DIP switches to turn on the filters one at a time to verify that the new filter was operative and that it increased the selectivity.

My roofing filter is setup for a 700 Hz CW offset. I suspect that Inrad chose 700 Hz as a compromise match for for their narrow 9 MHz CW filter (which has a 600 Hz offset) and the Ten Tec 9 MHz IF filters which have a 750 Hz offset.) In practice I've been able to use the combined filters with CW offsets as low as 550 Hz, although I do notice the slightly asymmetrical response, due to the unequal center frequencies of the roofing filter and the downstream IF filter. The asymmetry can be avoided simply by operating with an offset of 600 to 650 Hz.

In an e-mail message, George at INRAD told me after production of the Omni roofing filters officially begins, it can provide a lower CW offset (say, 500 Hz, to match the Ten Tec 221 9 MHz IF filter), if there are ten or more customers for such a special request.

I've found enhanced selectivity with the new roofing filter, and the combined effect of it and the 400 Hz filter at 9 MHz are very noticeable, even when using a 250 Hz filter in the second IF (6.3 MHz). I have a couple of very close neighbors (within 1000 ft. or so) who are fellow DX'ers who use KW amplifiers. Several nights ago, I made an 80m CW QSO while one of my neighbors was calling in another pileup only about 6.5 KHz above me. This QSO simply would not have been possible without the new roofing filter.

My congratulations to INRAD for coming up with effective ways to improve our radios that are so simple to install.
WO8USA Rating: 2004-12-30
WOW! I would not have believed it! Time Owned: 0 to 3 months.
You just have to hear it to believe it!

In experiments today, I had several S9+20 or S9+30 dB stations I monitored (conditions were good today!). Before adding the roofing filter (I had no other add-on filters) the drop off in the spillover would have been gradual and probably conintued for at least 6 kHz either way of the signal of that strength. After I added the INRAD Roofing Filter, the signal just disappears at 3 kHz!

One particular station I experiemnted with was on 14.250 at S9+30dB. With just the roofing filter (no other filtering features engaged) the bleedover from the signal was down to S9 or so at 14.248. at 14.2469 the audio from the signal just disappeared!

Continuing on, I also got INRAD 715C and 716 filters for the Mark V. During this test, I then turned on the filters. At 14.24690 I had no indication of the S9+30 dB signal (I used my clarifier to go back and forth to make sure it was actually there). In the mean time I discovered a S6 signal there and could copy it 100%!

I tested this out several times on other strong signals as well (you do not notice any performance if the signal isn't above S8 or so or bleeding more than 2 Kc).

I could not test the performance with multiple strong signals so I do not knwo the perforamnce with two S9+ signals spaced within 2 Kc.

I could definitely tell that the roofing filter is greatly enhanced by other filters installed. The rwsults weree even better when intermixing the filters, IDBT, EDSP, VRF, etc......

INSTALLATION: I am not used to poking around inside my $2000 radio, and was somewhat nervous about the soldering necessary for teh Mark V (the MP does not need soldering. The hardest part is removing the wire insulation AFTER the 2, 1-inch wires have been soldered---everything else is a breeze if you 1) read their instructions and 2) look at the wonderful FT1000 web site at http://www.va3cr.net/default.htm
The pictures there of a similar mod help prepare you.

I have to say that the addition of the roofing filter, in conjunction with my other INRAD filters, make this radio sound like a much better receiver. I don't know what the IC7800 or other radios sound like, but this investment is like buying a new and better reciver.

Email me if I can help you, my eHam profile is active.

Chris WO8USA
S57OWW Rating: 2004-12-29
OK. you can also bypass the filter Time Owned: 0 to 3 months.
I'm using the filter for a week now (Markv-field). You can have a lot from the filter also 2khz away from strong station....you just use the shift and width control. I can work 8khz away from station whish has the signal 9+45db with disconnected antenna! You can imagine how strong the signal is with antenna pluged in.

I didn't find anywhere wriiten that you can bypass the filter with 5-0 menu setting on 8.2-455. Than you can receive 6khz wide on ssb on the nor position. On the nar1 the default filters are on with roofing filter on first if. On am that doesn't work...I think.

73, s57oww de Tilen
IC8POF Rating: 2004-12-27
switchable roofing filter unit Time Owned: 0 to 3 months.
In 2 weeks of use I have not been very impressed by that filter, must wait for a next BIG contest and try it better.
Anyway I have built a switching unit for the roofing filter in my FT1000mkVField and am writing the full story and experiences on my web page:
www.qsl.net/ic8pof/howto/roofing%20filter/switchable.htm .
Happy New Year to All de Phil