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Reviews Categories | Filters, RF: bandpass, lowpass, highpass, RFI/EMI, etc.. | PAR SCANNER INTERMOD FILTERS Help

PAR SCANNER INTERMOD FILTERS Reviews: 30 Average rating: 5.0/5 MSRP: $74 USD
Description: These scanner filters are used to eliminate interference from high powered pagers and channel "skipping" from other frequencies. The filters are designed to eliminate specific offending frequencies.
Product is in production.
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KD4NVS Rating: 5/5 Apr 22, 2011 16:57 Send this review to a friend
Excellent!  Time owned: 0 to 3 months
Ordered this filter because NWS put a new TX 2 miles from my house & was having awful intermod issues. I purchased this based on things I read on and through Grove Enterprises / MT. When I installed it, it worked great, but after about 2hrs, I noticed some signals were not quite right & removed the filter, and they came back. I emailed Grove thinking maybe it was just a fluke & he fwd to PAR. PAR was able to replicate my issue & made a tweak to the design & sent me a new one!!! Can you believe that? I really cannot put into words how much I recommend both Grove & PAR!!! These two companies remember what customer service is & and practice it.

This filter works great!!! I'm able to up the squelch to bring in the dx VHF Hi that was overrun by WX...

To quote myself from a few days ago, "hate to be rude, but it's time to do some scanning :)"
KB3KLQ Rating: 5/5 Mar 23, 2011 08:08 Send this review to a friend
New Life for my Pro-197!!!  Time owned: 0 to 3 months
Here's a copy of the email I sent to Dale about the FM Notch filter:


Received the FM Notch last night, Dale...WOW! Like having a new radio! I have the Pro-197, which is (I'm sure you know) notorious for its sensitive front end. This radio was DEAF on the VHF airband and railroad band. Now I get non-stop activity. I'm in Chattanooga, which is a major rail hub, and the band has really come alive. We're also on the Tennessee River, so I KNEW there was tugboat activity I was missing. Sure enough, I'm hearing traffic there too. Not much, but then again, I've NEVER heard marine activity on this radio before.

Great product! Well worth the price! Thanks, Dale!"

As an FYI, the scanner is connected to a Diamond X50A
VK5FMLB Rating: 5/5 Aug 28, 2010 16:30 Send this review to a friend
Excellent filter for removing pager interference  Time owned: 0 to 3 months
I recently installed a high gain dual band (2m / 70cm) base antenna for my scanners at home. The antenna works brilliantly, significantly improving the reception on VHF and UHF over the Discone that I had previously used.

Unfortunately due to my proximity to a number of high powered commercial paging sites I was suffering severe de-sensitisation on the VHF frequencies between 140mhz and 160mhz.

After some investigation I ordered a VHFSYM HT M/F BNC filter tuned to 148.5mhz

I can report that it works perfectly.

All of the paging noise on the 2m amateur frequencies has been removed and I can now hear a lot of the repeaters that were swamped with noise without the filter.

Dale is excellent to deal with and for $100 delivered this piece of equipment is one of the best things I have purchased recently.

I can definitely recommend this product.
W2GLD Rating: 5/5 Jun 20, 2010 12:36 Send this review to a friend
Filters Work - Use Them  Time owned: 0 to 3 months
I've been involved in the hobby for many years and have been resistant against introducing any additional connection points in my antenna system that I didn't need. Well I am here today to say that I am dead wrong!

I have used scanners from all sorts of manufacturers including GRE, Radio Shack, and Uniden to name a few. My current setup is a (2) GRE PSR-600's & (2) Uniden BDC996XT's connected to a Stridesburg multicoupler and a Diamond discone antenna mounted in the attic.

Located less than 13 miles outside of Philadelphia, PA; I reside in a VERY RF SENSITIVE area. There are FM broadcast transmitters and NOAA sites nearby as well as countless local, state, and federal transmitters. NOT a very RF friendly environment for scanners, especially those GRE models, useless without these filters.

To make a long store short, I have encountered various reception issues within the VHF/UHF bands and found that the local FM broadcast stations were one main cause. I immediately order the VHF-FM filter and placed it in-line and all I can say is WOW... For those of you who have the GRE PSR series scanners, this filter is a MUST. You can actually use VHF now without the need for the ATT to be one. All in all, this is by far the best $83 I have ever spent on my receiving station.

The service is excellent from this company, the communications with the owner are superb via e-mail. I recommend any serious listen to purchase at least the VHF-FM filter if your are located in a major metropolis such as Philadelphia.

I give this product, the company, and the support staff *****(5-Stars)
F6GYY Rating: 5/5 Jan 12, 2010 10:54 Send this review to a friend
Simply great  Time owned: 0 to 3 months
Problem : severe intermodulation from 3 FM transmitters of 50 KW , about 4 km away...

Set-up : collinear 2m / 70 cm with TGN LN preamplifier 50-1500 MHz with 20dB
on the roof... + PAR-Filter with Icom receiver IC-8500 at the station....

=> no internodulation at all ...on the 4 m band ....from 80 - 87.5 MHz by continious scanning
over 3 hours....( squelch and s-meter down.... ) ...Music has also gone on the higher VHF and on UHF....

Small and efficient little filters of high quality, which finally solved the problem..
PA3GTS Rating: 5/5 Oct 20, 2009 06:07 Send this review to a friend
Ideal no problems more in the airband  Time owned: 0 to 3 months
Hello every day problems here with the local radio on 104.7 mhz in the airband vhf, i ordered a fm filter from Dale and in our e-mail contact he asked to give the freq and later received the filter and works great no problem more on my scanner,also the communication with Dale was also perfect !
With friendly greetings from Jelle pa3gts 7s s !
K8CMI Rating: 5/5 Jun 25, 2009 06:14 Send this review to a friend
Now I'll keep my scanner  Time owned: 3 to 6 months
I was ready to just sell the scanners and give up. I have an FM broadcast antenna located about 2 miles from my house. Their signal was on every vhf channel I scanned. The frontend of the scanner was so overloaded that I had to attenuate everything, including NOAA, just to receive anything.

I found Dale's filters on eHam and gave it a try. The offending signal are GONE! The attenuation is off and I now receive signals that I had previously given up on.

Dale is great to work with. He actually RESPONDS to his emails. Usually within the hour. My offender was at 104.9. Out of the box, the filter has a pretty deep notch near this frequency. Dale offered to tune the filter to put a notch right at 104.9. That's customer service.

Thanks Dale!
W6LBV Rating: 5/5 Apr 13, 2008 21:47 Send this review to a friend
A (grief) filter that works  Time owned: 0 to 3 months
The Par VHF-FM Notch Filter solved a real and vexing problem for me. The FCC, in its customary institutional laxity, approved license upgrades for two local FM broadcast radio stations that took each of them upwards in power to 50 kilowatts ERP! The transmit antennas for these stations, whose broadcasts are of no interest to me anyway, are located within a metropolitan residential area on a tower that lies just over four miles away in a direct line of sight from my residence. At my dwelling, using a broadband discone receiving antenna located in the clear ten feet above ground and a spectrum analyzer, I measured received signal levels from each station of -16 dBm. When that signal level is developed across a 75 ohm receiver input, it yields more than 43,000 microvolts! (Typically, “S-9" is taken to be 50 microvolts.) These two are the strongest measured off-premises signals at my residence between 0 and 1,000 MHz, and probably in the entire RF spectrum. Few, if any, broadband receiver front ends are going to handle a signal of that magnitude without folding into compression.

That grossly excessive signal level is really needed only for receiving broadcasts on electric toothbrushes! There is no rational purpose in using this great a power level in my area, since VHF signals are always blocked by existing terrain before they can decrease to the noise level at far distances. It’s no wonder that my sensitive monitoring receivers on outdoor antennas curl up and die whenever they are tuned to within a few tens of Mhz of the FM broadcast band. The Par filter, working ahead of a broadband distribution amplifier and the receivers, solved the problem. The receiver blanketing is essentially gone!

On-air testing of the filter using the spectrum analyzer confirmed the published specifications. My several monitoring receivers (30 kHz to 2 Ghz) also expressed their relief at no longer having to work under that crushing load!

There are some (small) niggles with the filter: it would be helpful to have multiple tuneable traps in one filter, since I have two 50 kW FM loudmouths to silence (and two more at the same power level just another mile farther away). And, as expressed by others previously, the filter needs some sort of physical mounting tab arrangement so that it can be permanently fastened to a chassis or rack panel (but industrial Velcro will also work).

The filter is somewhat pricey, but it does the job very effectively and significantly better than most competing products. Dale Parfitt is splendid to work with, as he always has been.

For many years I unquestioningly believed that “bigger outdoor antennas were better antennas.” Finally I measured actual received signal levels. And I discovered that the real problem was far too much RF in the air over my residence, not too little!

AA8IA Rating: 5/5 Apr 6, 2008 19:51 Send this review to a friend
Great Product, Excellent Service!  Time owned: 0 to 3 months
I live at a high elevation in my area, and even though I live out in the country I was hearing severe intermod and significant front end overload on my scanner.

I gave PAR a call, and lo and behold Dale answers the phone and talks to me. I discuss my problem with him. We discussed the likely possibilities and agreed that my local TV Ch 9 was the strongest offender. I ordered a PAR filter to attenuate the 190 mhz region.

When I received the PAR filter, Dale had included a note that stated what he had done in my particular case since the TV signal is actually within a 6 mhz spread, wider than what the typical filter has to attenuate.

I inserted the filter inline and immediately noticed a significant improvement. My initial thoughts were that it significantly lessened the intermod but did not remove it completely. However, I was left with occasional interference across a wide range of VHF that I [erroneously] contributed to remaining TV 9 signal still affecting some areas. Further investigation revealed that the remaining interference I was hearing was due to my local cable company having significant leakage in teh area of my old house, which was affecting certain areas of VHF from the Aero band all the way up to 170 mhz. I hadn't noticed the cable leakage before because of the other problems [which the PAR filter cured].

I then moved to a new place a mile away. I fired up the scanner without the PAR filter and the symptoms were back once again. I put the PAR inline and VHF scanning was totally quiet [i.e. normal] - No odd interfering signals popping up anywhere.

In my opinion, the product is commercial grade. It is built tough and with quality components. You can tell that Dale takes pride in what he builds. The filter is small enough and light enough to leave inline on my handheld scanner connected directly to the antenna jack without fear of having the weight of the filter causing problems with the connector base.

It was great to talk to Dale when I called. These days, you're lucky to talk to an American let alone the manufacturer himself. He explained to me what I should get, how it would benefit me. He didn't try to oversell. He was courteous and obviously is an intelligent man.

Every email correspondence I have had with Dale was answered promptly. My satisfaction level could not be any higher.

The bottom line - Dale builds excellent products at reasonable prices and supports his products, should you need support. If somebody were to ask me to describe Dale, I would describe him as meticulous and a true professional.

73383 Rating: 5/5 Dec 30, 2007 14:52 Send this review to a friend
Very Good Product  Time owned: 0 to 3 months
I purchased a new Yaesu VR-5000 wideband receiver and was immediately disappointed in the quality of the receiver front-end. I presently use it to monitor the aviation VHF and UHF bands of 118-137 MHz and 225-400 MHz.

Whereas all my other receivers work fine with my outdoor Diamond D130JN discone antenna, the VR-5000 receiver had serious overload and intermodulation problems from FM stations. I was receiving local FM stations all over the VHF and UHF bands. The resultant noise was so bad that I could not squelch it without using the receiver's built-in ATTENUATOR. Of course, this ruined desired signal reception.

This problem led me to PAR Electronics and I purchased one of their VHF-FM Broadband 88-108 MHz filters. Prior to ordering, I checked the FCC's FM Radio Database Query site at using the "Stations Within a Radius" query form. This searches for stations within a specified distance of your specified coordinates. The query response lists all licensed FM stations and their distance and azimuth. The closest and most powerful station was at 101.3 MHz, 2 miles away.

I ordered the filter and specified the notch to be set at 101.3 MHz. This is a nice feature of the PAR Electronics filter - you can ask that it be tuned to specific frequencies (within technical limits) at no extra charge.

When I received the filter, it included a brief specification sheet and a stopband response printout. This filter actually has three notches in the FM band. In my case, the notches were 90, 98.0 and 101.3 MHz; the notch at 101.3 was about -49 dB with respect to response at 120 MHz.

I installed the filter and it solved the interference problem. I can now set the squelch normally and receive aeronautical stations quite well. I occasionally hear interference on a few frequencies but it seems to come and go, and the frequencies in question do not seem to be active in my area.

My only complaint about the filter is there is no convenient way to fix-mount it to a panel. The filter is designed to plug right into the BNC-F connector on the receiver. The filter comes with a BNC-M on one side and BNC-F on the other - this makes it easy to cascade more than one filter if necessary. While this is somewhat convenient, it does mechanically stress the receiver connector. I asked Dale Parfitt at PAR if I could drill and tap the filter body but he indicated that the material was a relatively thin brass extrusion and not really suitable for that. He said that on future filters he could accommodate any mounting pattern I need. This is another nice thing about PAR - the personalized service and quick response you get, something missing from many companies these days.

It's too bad the VR-5000 receiver designers did not build a good front-end, but it's good that PAR Electronics makes a filter to compensate for it.
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