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Reviews For: DCI VHF Filters

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

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Review Summary For : DCI VHF Filters
Reviews: 19MSRP: CALL
Description:
General purpose filters used for reducing intermod.
Product is in production
More Info: http://www.dci.ca/?Section=Products&SubSection=Amateur
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00194.6
K5UJ Rating: 2003-06-19
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
http://www.dci.ca
email: dci@dci.ca
K7NG Rating: 2002-12-01
Great! Time Owned: more than 12 months.
I have one of the DCI 144-146 MHz and one of the 222-225 MHz filters. They WORK. They are temp stable, don't have too much insertion loss, and the signals that crossmodulate the frontend of my gear just aren't there anymore. It's a little surprising how many of the distant repeater or simplex signals you might hear come right up out of the noise when the RF environment presented to the receiver is rid of dozens of super-strong carriers...
They are a little fragile, so be careful - they are fine in a mobile installation if properly mounted and installed, but if you drop one off a workbench onto a concrete floor it might not be anything like the filter you bought.

73, K7NG
N8WLG Rating: 2002-06-21
Works as advertised! Time Owned: 0 to 3 months.
I live within 500 meters of major FM broadcast towers, all with greater than 1MW ERP. Before I added the DCI filter, EVERYTHING had some form of intermod/overload attached to it. Now I can hear a bad filter cap in a repeater 25 miles away! This unit cured ALL my intermod/front end overload problems, 100%! I would recommend these filters to anyone experiencing problems that conventional stubs will not cure. They work. Plain and simple.
KD4WOV Rating: 2001-01-20
What a filter Time Owned: 6 to 12 months.
I have a huge problem with intermod. Even my comercial radios get swamped by inter mod. I put a UHF band pass filter in line and no more inter mod. most signals were increased by 3 s units due to the recievers not being swamped. i can now hear stations that were not even detecable.
KG5U Rating: 2000-02-04
DCI VHF & UHF Bandpass Filters = Outstanding perfo Time Owned: unknown months.
A year or two ago, I was asked to spec the equipment for a ham station in our Emergency Operations Center at Johnson Space Center. Once the VHF/UHF radios were in place, it was patently and painfully obvious that BP filtering was necessary. Our dual-band vertical antenna was on the Mission Control Center roof in the antenna farm. DCI VHF and UHF filters were purchased and put in place and not a peep has been heard of intermod or any other effects. I bought a VHF BPF for the house and will now be buying a UHF filter now that I have a duo-band VHF/UHF radio. I'm even considering a pair for the car.
KL7DC Rating: 2000-01-12
They work! Time Owned: unknown months.
Mega Dittos! It solved my intermod problems on the 2 mtr base station here in Eagle River, AK ( a suburb of Anchorage). Well worth the money. 73.
AC5AA Rating: 1999-12-14
It really works! Time Owned: unknown months.
My IC-706mkII has the typical horrible intermod on 2m. For this reason and because of reported failures of a diode in the the 2m front end caused by RF coupled from the HF antenna on the car, I decided to install the DCI-146-4H filter. It is superb. I can drive right through Austin's intermod alley and never hear a peep from the rig. Receive sensitivity does not appear to be degraded. I'm very pleased, and it's built to last a long, long time.
KC2EZV Rating: 1999-12-08
Something that works the way it is supposed to! Time Owned: unknown months.
I live in NYC, right across from the World Trade Center and other RF monsters. Intermod is my middle name. I hooked the DCI 2M 4MHZ filter between my FT-847 and my tri-bander and the difference was amazing! My friend who lives about 20 miles away in Queens was always in the noise -- with the filter he was a solid 2 on my S-meter. Almost DFQ! I highly recommend this product to anyone.
VE6SZR Rating: 1999-11-27
DCI Filters, worth their weight in gold! Time Owned: unknown months.
This is one of those few products that truly delivers on ALL of its promises, so good that I have 2 of them. Its a passive design requiring no external power, my model is the wide bandwidth version which allows operation from 144-148Mhz. Steep rolloff on the band edges. Custom versions are available for more narrow operation (2Megs) if necessary. The receive sensitivity that will be gained more than outweighs any losses resulting from having it in line (especially on simplex). About the only drawback to this item is the size of it, its not a "pocket" item. Also, you don't want to drop or shake it, as it will detune the helical resonators. No regrets with this product at all.