Block broadcast FM interference with an FM notch filter

I noticed recently that I have some interference on the aviation bands with my RTL-SDR. After tinkering with it for a bit, I noticed it was coming from a local 50,000 watt FM broadcast station within one mile of my home. I looked around online and it was recommended to get an FM notch filter. That would hopefully block out the FM broadcast band signals (88-108 MHz) getting into my SDR.

I ordered one made by Nooelec called the Flamingo v2 FM Notch Filter. It’s pretty simple to hook up. You plug in your antenna on one side and the other side goes to your SDR. It comes with an adapter to hook it up directly to your SDR which was nice. I immediately noticed the 50,000 watt FM station was gone from both the aviation band as well as from the FM broadcast band. Not bad for $22!

One thing I noticed is that the filtering drops off around 105.9-107.9 MHz. While stations aren’t as a strong in that range, they’re definitely visible on the waterfall. So if you have a super local strong station in that area of the band this filter might not solve your FM interference. Still, for $22 it’s definitely worth a shot.

If you’re interested in buying this FM notch filter, I’d appreciate it if you went through my Amazon affiliate link below. There is no extra cost to you and I receive a small commission which helps support my content. Thanks!

Flamingo v2 FM Notch Filter: https://amzn.to/3ZEHVu9
RTL-SDR v3 SDR (w/antenna): https://amzn.to/3I9rcbP
RTL-SDR v3 SDR (dongle only): https://amzn.to/3XmNyem

I also made a video demonstrating this filter hooked up to my RTL-SDR. Check it out and let me know if you have any questions or comments. Thanks!

Gaia GPS and ham radio

I use the Gaia GPS app on my iPhone for finding and recording various hiking trails around me. I discovered you could import GPX, KML and other files into Gaia GPS. I thought it would be cool if I could add some ham radio items right into Gaia GPS. After some research, I was able to import GPX files from Repeater Book, POTA and SOTA websites.

Repeater Book

  • Go to the RepeaterBook.com website
  • Log in if you haven’t already and click on North American Repeaters.
  • Click on the state you are interested in. I chose Illinois since that is where I am.
  • Choose whichever criteria you want. I chose All for simplicity.
  • You should see a list of repeaters. Click on Export at the top and choose GPX.
  • Click OK on the warning screen.
  • It will ask you to choose what two labels you want. I picked the Callsign for #1 and Location (City) for #2.
  • Check the box that says “I agree to use this data for personal use only.” and then click Download.
  • In your downloads folder, you should now have a GPX file called repeaterbook_repeaters_datetime.

Parks on the Air (POTA)

  • Go to the POTA website and make sure you are logged in.
  • Click on the menu in the top left and choose Park List.
  • Scroll down to the United States and click the triangle on the left side to expand the list.
  • You should see a second listing for United States that shows all the individual states.
  • Click on the state you want.
  • With the list of parks listed, click on the Download link and choose GPX.
  • In your downloads folder, you should now have a GPX file called State(US-State). Mine says Illinois (US-IL).GPX

Summits on the Air (SOTA)

  • Go to the SOTA Maps website and make sure you are logged in.
  • Under Association at the top, choose the area you want to import. I chose W9 – USA since that is where I am located.
  • Under Region at the top, pick the one you are interested in. If you want all of the regions in that group, check the Multi box above the dropdown box. I picked W9/IL, W9/IN, W9/WI.
  • At the bottom of the list of summits, click the export button.
  • As before, choose the association and regions you want.
  • In the output format dropdown, choose GPX file and then click Create File.
  • In your downloads folder, you should now have a ZIP file called SMP_Date_Time.zip. You’ll need to extract the GPX file from the ZIP file before importing it to Gaia GPS.

Importing to Gaia GPS

Now that we have GPX files from each site, we can import them to Gaia GPS.

  • Go to the Gaia GPS website and make sure you are logged in.
  • On the menu on the left side of the screen, click on Import Data.
  • Click on select files and select the GPX file we downloaded from Repeater Book.
  • Check the Waypoints box and click on Import.
  • You should now see a list of repeaters that were in the GPX file. Click the Save Items button at the bottom. This will take a few moments depending on how many repeaters you exported.
  • When it’s done, you should see a list of your repeaters on the map.
  • Repeat these steps to import the GPX files from POTA and SOTA

Changing the icons

I like to change the icons to make them represent each group whether it’s a tower for a repeater or a tree for a park.

  • Click the Saved Items on the left menu.
  • Click on one of the imported files.
  • Click on Items.
  • Click the circle to the right of the first item. Then click the circle above it to select all the items.
  • Click the 3 dots next to the circle and select Set Icon.
  • For the repeaters, I used the tower icon. Type in tower and click the icon and click Save.
  • Depending on how many repeaters or other items you imported, it could take a while to change all the icons. When I did it, I had to repeat this process numerous times until all the icons changed to the new icons.

Now if you go to your phone and login to the Gaia GPS app, you should see the the imported items on your map. Pretty cool isn’t it? You can shut layers off and on as needed so they don’t clutter your phone or slow it down.

Let me know if you have any questions about this process or if you have other suggestions on what to import into Gaia GPS.

You can download Gaia GPS for iPhone or Android below.

iPhone: https://apps.apple.com/us/app/gaia-gps/id1201979492
Android: https://play.google.com/store/apps/details?id=com.trailbehind.android.gaiagps.pro&hl=en

I also made a video on how to import data from Repeater Book, POTA and SOTA into Gaia GPS.

Where to buy used ham radio gear

Local

Online

Dealers

I also made a video about this topic which you can watch below.

2023 ARRL Repeater Directory Review

Back in the day, I couldn’t wait for the ARRL Repeater Directory to come out and see all the changes and new repeaters in the area. With the popularity of the internet, I haven’t felt the need to buy the directory in a long time. At the beginning of 2023, I thought I would take a chance and buy the latest edition and see what it was like.

The first major change is that it’s a lot bigger than it used to be. It’s nicely put together in a spiral format which makes searching through the book very easy. It’s very similar to the ARRL license exam study guides.

The next thing I noticed is that since 2017, the ARRL doesn’t manage the list of repeaters. That is now done by a company called RFinder who also has a paid web-based repeater directory service.

When I thumbed through the first few pages, I noticed a grammatical error of three words bunched into one word with no spaces. Weird.

Anyway, I went to the Illinois section and looked up Champaign. Odd, the 146.760 repeater was not listed. This is a popular repeater that has been around for decades. I then looked through the entire state of Illinois thinking maybe they put it in the wrong city. Not only did I not find that repeater, but there were no 146.760 repeaters listed for the entire state.

I knew of at least three repeaters off the top of my head on that frequency that should have been listed but were not. I went to the Illinois Repeater Association website and they listed four repeaters on 146.760. The same four repeaters were also listed on the free RepeaterBook.com website. Not a good sign for the book.

I also noticed that most D-STAR repeaters were listed twice for no reason. They could have saved a lot of space in the book by only listing them once.

Another thing that frustrated me is that they listed the NOAA weather radio frequencies but decided to put them all under N instead of with their appropriate cities. One extra step to go through.

Finally, to prove this book doesn’t have much quality control, I stumbled across an entry in New Jersey called “TEST Anywhere, NJ”. Really!? Maybe someone sent the rough draft of the book to the printer instead of the edited version but really not a good look.

Sadly, I can’t recommend this book. If you are looking for quality repeater information, I recommend either RepeaterBook.com (which is free!) or find your local repeater association / council which usually has all the latest information. If you already have the book, you can go to page 16 to see a list of all the repeater associations in the US.

Here is my video review of the 2023 ARRL Repeater Directory.

Sangean HDR-14 HD/FM/AM radio review

I had originally purchased this radio back in May 2020 from Amazon as a renewed item to save a few bucks. Unfortunately, something was wrong with it as it struggled to pick up even the 50,000 watt power house FM station one mile away from me. After talking with folks who had the radio and loved it, I thought I would give it another chance. In October 2020, I purchased the radio brand new. When I received it, I was blown away at all the stations it was picking up. Now that I’ve had it a few years, I thought I would do a review of the radio.

Likes

Portability

One of the biggest features of this radio is how small it is. It fits in your hand and you can take it anywhere.

HD Radio

Why do you need HD radio capabilities? Despite slightly increased music quality, I think the real benefit of HD is having multiple stations on the same frequency. Two of our stations here in Champaign, IL have three separate HD channels on the same frequency.

WILL has two of their HD channels for classical music. The third is crystal clear audio of their AM station which sounds a lot better than what you would hear on an AM radio.

Then you have WIXY which also has three HD channels. HD1 is country, HD2 is hip hop and HD3 is top 40. That seems pretty cool from a technical perspective of only needing one transmitter for three different genres of music. However, many of these stations are also on FM, albeit on different frequencies than their main transmitter. Their HD1 channel is on 100.3, HD2 on 92.1 and HD3 on 99.7. This allows folks without an HD radio to enjoy those stations with a regular FM radio. Of course this requires the station to have three different transmitters which reduces the cool factor and increases their costs.

If you are curious what HD stations are in your area, you can visit the address below.

https://hdradio.com/stations/

Getting back to the radio… The HD reception on the radio works very well. It seems to detect and lock on to an HD signal in a few seconds which is nice. Audibly, you really don’t hear any difference with an HD signal on the built-in speaker other than no static. If you plug in headphones, you can sometimes hear a slight improvement in signal.

Radio Data System (RDS)

On the FM side, one of the wonderful features is RDS. This is the system that shows you the artist, song title, station call letters and more. Most car stereos have this built-in but most portable radios do not. This radio does a good job of detecting and then decoding the RDS portion of the signal to display the information on the screen. I also enjoy using this feature to DX or listen for distant stations outside your normal listening area. When certain atmospheric conditions are right, you can hear stations from hundreds of miles away. I’ve picked up FM stations in Wyoming (I’m in Illinois) before just using this radio and the built-in antenna. Being able to see the call letters on the screen is a huge help in determining where a station is located.

In July during this past summer, I picked up WXOS out of St. Louis, MO which is about 160 miles southwest of me on this radio. Not only did the RDS show me the call letters but their HD signal was decoded as well!

Batteries

This radio uses three AA batteries to run. The nice thing is you can find AA batteries at just about any store so you should never run out of power. I use rechargeable AA batteries so I can use them numerous times. Sadly, there are no batteries included with the radio.

AC adapter

Don’t fret about batteries not being included. Sangean has included an AC adapter with this radio. They do mention in the manual that if you use the AC adapter when listening to the AM band, you will hear increased noise due to the electronic components of the AC adapter. It doesn’t affect the FM band though.

Lock Switch

There’s nothing like throwing your radio in a bag and getting ready to use it at your destination and you notice the batteries are dead. This is why I like the lock feature on this radio. It prevents the buttons from causing the radio to come on inadvertently.

Dislikes

AM Bandwidth

I noticed when moving the radio around on an AM station that the bandwidth changes based on the signal strength. It gets more narrow on a weaker signal and wider on a stronger signal. Technically that’s a pretty cool feature but I would appreciate the ability to adjust the bandwidth manually. I have that capability on the C.Crane Skywave SSB radio that I’ve reviewed in the past.

No direct frequency entry

I’m nitpicking here again, but there is no way to enter a frequency by typing it in. You must use the up and down arrows to change the frequency. Of course you can store up to 20 frequencies per band as a preset which might save you some time.

Backlight

The backlight on the radio is nice but there is no way to leave it on continuously. Even plugged into AC, it shuts off after a few seconds. It would be nice to have an option to leave it on all the time or leave it off all the time.

Price

If you’re looking for a cheap portable AM/FM radio, this radio is probably not for you. This radio costs $80. However, if you want a radio that has AM, FM and HD radio with RDS built-in, then this is definitely a radio to consider. I think it’s actually worth the price for what all you get with it.

Where to buy

You can buy this on Amazon for around $80 + tax. I would also recommend getting a hard shell case for it to protect it.

Sangean HDR-14 Radio: https://amzn.to/3sOHKxA
Hermit Shell Hard case: https://amzn.to/3SxCEzS

Note: The links above are affiliate links which means I may receive a small commission should you buy anything through those links. If you do purchase through those links, it helps support my site and I greatly appreciate it!

Gallery

Video Review

I also put together a video review of the radio if you want to check that out.