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Reviews Categories | Filters, RF: bandpass, duplexer, lowpass, highpass, RFI/EMI, e | DCI VHF Filters Help

Reviews Summary for DCI VHF Filters
DCI VHF Filters Reviews: 18 Average rating: 4.6/5 MSRP: $CALL
Description: General purpose filters used for reducing intermod.
Product is in production.
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G7UTB Rating: 5/5 Oct 3, 2017 08:02 Send this review to a friend
Forgot how good they are  Time owned: more than 12 months
I have just moved my shack into a bigger room. Connected all new cabling patch leads etc and switched on the 2m multi-mode. Inter-mod across the band! I had left the DCI filter forgotten behind the old desk. Patched it in line and all quiet again. I had forgotten how effective it had worked for the last 20 years or so. Looking at communication tower 120m away I thought what a great investment the filter was.

AB5Q Rating: 5/5 Sep 9, 2012 13:41 Send this review to a friend
Excellent Filters  Time owned: more than 12 months
Living in an area 20 miles line-of-sight west of a multi-megawatt RF curtain of VHF/UHF transmitters, even the most robust receiver front end needs help with weak signal reception. Over the past several years I've purchased used DCI bandpass filters for VHF/UHF to help improve my receiverís S/N ratio looking east. As a secondary benefit, the filters also protect sensitive GaAsFET and PHEMT receiver front end circuitry from strong out of band signals radiating from nearby antennas. The filters also provide a means to shunt the receiverís front end to < 0.1-ohm above dc ground potential. The filters have easily reduce my noise floor looking east by 3-6 S-units resulting in an MDS of < -100 dB in most cases. Typical random, continuously shifting, intermodulation distortion has transitioned from s9+20dB levels to a state of non-existence. The filters work as anticipated however the customer service/direct order processing is broken but thatís a subject for another forum.

One final note, the $119.00 MSRP listed in this particular review is a bit out of date. These filters now cost between $400-500 new, and from $250-300 on the used market.
WY3X Rating: 5/5 Jul 17, 2011 11:55 Send this review to a friend
Works like a champ!  Time owned: more than 12 months
KT6KT, hopefully 435~450MHz is not in the passband of your 2M radio! If it is, you might want to replace the radio, not the bandpass filter! I find it eliminates VHF-HiBand paging interference at my location on 2M, where my primary objective is 2M SSB near 144.200. I got mine for a bargain price, and it works great! The spec sheet doesn't go up as high as 435MHz, so you can't really say they misrepresented it. It's mostly for notching out VHF-HiBand interference. Perhaps you bought a boat intending to drive it on the highway...?
KT6KT Rating: 0/5 Jul 16, 2011 21:21 Send this review to a friend
More BAD News  Time owned: more than 12 months
The attenuation of a DCI-145-2H filter between 435 and 450 MHz is less than 10 dB.
Photo available on request.
VE2DC Rating: 5/5 Jan 31, 2010 08:18 Send this review to a friend
Very effective.  Time owned: more than 12 months
Ever since they started making Amateur VHF/UHF gear double as scanners (a dreadful idea in my opinion) many radios are horribly prone to intermod. This provides the necessary selectivity.
GM1SXX Rating: 5/5 Feb 11, 2006 07:03 Send this review to a friend
Superb intermod killer  Time owned: more than 12 months
DCI 144-146Mhz (UK) 4 chamber VHF filter.

I have one of the 4 chamber VHF filters.

I live in a large town (pop. 85,000)and pager breakthrough was a perennial problem. The 2M band was very noisy until I bought this filter. I now know that 2M is not so bad after all, in fact its actually very good.

All of the problems I had have completely disappeared showing that poor design of the front ends in my radios was to blame.

If you live in a high RF environment I can thoroughly recommend these filters. They are very well made... yes I did do the unforgiveable and carefully took mine apart for a look, although I really don't recommend this. Mine was second-hand so it wasn't such a big deal.

The filter is built from four pieces of square section alumin(i)um extrusions screwed to solid brass top and bottom plates with machined coupling slots between the chambers. The resonators appear to be made of central-heating copper microbore tube and are self-supporting with additional foam tubes tucked in between the edges of the cavities and the resonators for additional support. The earthy ends of the resonators are flattened and soldered directly to the brass baseplate making for a strong and rigid assembly. No capacitors are used in this filter and it has no adjustments, having been factory aligned.

Build quality and performance is superb. Insertion loss is very low indeed. Sweeping the filter using my HP141T SA & HP8444A tracking generator confirms the excellent performance.

These are very fine filters indeed.
I have to give this filter a 5 on all counts.
It is one of my better purchases over the years.

73 Al.
KC4PX Rating: 5/5 Jul 8, 2004 11:52 Send this review to a friend
K4T DXpedition with excellent results  Time owned: 0 to 3 months
The K4T DXpedition team (Dry Tortugas) was fortunate to use DCI VHF Bandpass Filters on 2 meters and 6 meters. We had two stations running in the same tent, one on HF, the other on 6 and 2 meters. Both filters were the 4 pole type capable of handling 200 watts. Our first impression was how massive these filters were and very well made. As for operation, we never had a problem. Each station operated without any interference throughout the 4 days on the island. On the HF station, we utilized Array Solutions Bandpass Filters for 20, 40 & 80 meters. When considering a multi-op DXpedition or contest operation, having Bandpass filters on each band is a must, otherwise significant interference and operator annoyance would limit the efficiency and tolerance of each operator. I highly recommend these Bandpass Filters to anyone serious on weak signal and contest operation.
N1OFJ Rating: 5/5 Dec 10, 2003 12:30 Send this review to a friend
very pleased  Time owned: 0 to 3 months
Purchased a UHF custom rackmounted unit for use as a window filter for a 8 channel receive multicoupler (amateur use). Works as advertised with low insertion loss (confirmed with test eq). Nice steep skirt at band edges. Very pleasant people to deal with. Great bang for the buck. Will consider purchasing other products from DCI for future projects.

Dave N1OFJ
WB9PNU Rating: 5/5 Jul 8, 2003 15:19 Send this review to a friend
Worth every dollar  Time owned: 0 to 3 months
I am using an Icom 207H duo-bander in my Jeep.
I was experiencing lots of interference from intermod products, pagers, and other sources of rf. In some areas around St. Louis, MO it was almost impossible to hear even the repeaters. Now all is well. I just installed the dual band DCI bandpass filter a few days ago. Wow! What a difference. I haven't heard anything but other hams since installed. DCI filter is very massive, heavy, precision made filter. Worth every dollar I paid for it.
K5UJ Rating: 5/5 Jun 19, 2003 14:58 Send this review to a friend
High quality on a ham's budget  Time owned: 3 to 6 months
I'm trying to avoid ratings inflation (giving everything a 5) but in this case if it isn't a 5 it's real close as in 4.7.

I purchased the DCI-146-4H 2 meter band pass filter about 4 months ago from AES. I run a packet station to a dx cluster about 25 miles away and I was having trouble connecting. I could have solved the problem by putting up an antenna about 50 feet high (I'm in a river valley) but I get antsy above 30 or 40 feet because of the risk of lightning strikes. Preferring to run a 4 el. yagi lower down with a bit higher power, I worried about the data transmissions getting into nearby TVs and FM broadcast receivers. I figured a band pass filter would keep my end of things clean. Also, today's FM rigs have wide front ends--mine was suffering from a paging system and the filter was cheaper than another rig.

Besides custom filters, DCI makes a variety of filters for 2 m. - 70 cm. with either UHF or N connectors. All are rated at 200 watts and come with attenuation plots.

Mine arrived seemingly undamaged with UHF connectors. The metal work is nice to look at but I worried that in shipping, something inside may have come loose. Not confident enough to put it on the packet station and walk away (thinking I might leave the 30 watt amp working into an open circuit) I put the filter on a dummy load first, and hooked up an swr analyzer to it. As advertized, the swr dropped rapidly from >31 (the maximum the MFJ analyzer displays) very near 144 mhz and rolled around between 1 and 1.3:1 until just above 148 mhz, it zoomed back up again. The supplied swr plot for the filter shows an essentially flat response through the band (~1.07:1). I removed the filter and checked again to see if I was seeing the dummy load swr, and received the same response. My unit was essentially transparent.

The manufacturer's literature says, "The filter's design is four helical resonators with aperature coupling." N connectors are optional.
Mfr's specs.: 144-148 mhz. PB loss < 1 db.
Selectivity -57 db @ 136 Mhz; -43 db @ 156 Mhz
VSWR 1.5:1
Dimensions 12"x3"x5"
Wt. 2 lb 11 oz.

So far, I've detected no out of band interference. You may not need one of these if you have no neighbors close by, or are operating with robust equipment (Motorola for example), otherwise this is a company to keep in mind. They are one of several small companies making high quality products for hams at reasonable prices and filling a demand the big guys won't cover.
Contact information:
DCI Digital Communications Inc.
Box 293, 29 Hummingbird Bay
White City, SK, Canada
S0G 5B0
toll free 1-800-563-5351
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