POTA at Fort Dobbs: Testing a BCI filter and depleting a battery!

Friday, March 17, 2023 was a dreary, rainy day.

It was the sort of day made for reading a good book by the fireplace or…in my case…activating a park!

I don’t let rain stop me from playing radio in the field. I carry a rain fly in my car pretty much all of the time so if push comes to shove, I can create a dry space to play radio.

That said, a number of parks I frequent have large covered picnic shelters, so why not use what’s already there?

That particular Friday, I had one particular park and one particular goal in mind.

G106 + BCI Filter

As I mentioned in a post this weekend, I purchased and built a K9DP BCI Filter Kit.

If you’d like to see photos of the build, check out this post.

I built this BCI filter specifically to pair with the Xiegu G106 transceiver. Why? Because the G106 is prone to overload if you’re anywhere near an AM broadcaster.

The last time I visited Fort Dobbs State Historic Site (K-6839), a local AM broadcaster bled through the audio of the G106. I was able to complete the activation without any issues at all–in fact, it was a very successful activation (read the report here).

Still, I did feel that the receiver was a bit less sensitive due to the broadcaster overwhelming the front end of the radio.

That Friday, I wanted to pair my Xiegu G106 with the new in-line BCI filter to see if that might mitigate the interference I experienced before.

Fort Dobbs State Historic Site (K-6839)

After arriving at Fort Dobbs, and before taking my gear out of the car, I made my way to the park office (in the log cabin at the end of the sidewalk above) and asked for permission to use their picnic shelter.

Fortunately, no one had the shelter reserved so the park staff gave me an all clear to play radio as long as I wished. Woo hoo!

I went back to the car, grabbed my radio gear, and walked to the picnic shelter.

Instead of deploying an end-fed half-wave, I decided to use my Chelegance MC-750 vertical.

The MC-750 would give me the flexibility to move to any band between 40 and 10 meters without needing an ATU.

(Note that I include the full antenna deployment in my activation video below.)

I decided to start on 20 meters since that band had broadcast bleed-through during the last activation. I set the MC-750 whip to 20 meters (see above) and connected the antenna to the G106.

The G106 has no SWR or Power Output meter, so I had no way of confirming the SWR, but the MC-750 has been so reliably on the mark, I had no worries.

I turned on the G106 and heard no AM broadcast bleed-through.

It’s possible, I suppose, that the station was off the air this time or (more likely) that the MC-750, set to 20 meters, wasn’t receiving the AM broadcast signal as well as the larger 40 meter end-fed half-wave I deployed last time. I didn’t think about it at the time, but it would have been interesting to see if adding the 40M coil to the MC-750 would have made a difference.

All the same, I added the in-line BCI filter in the mix because the G106 receiver could be affected negatively even if broadcast signal isn’t audible.

Time to hop on the air!


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On The Air

I hopped on the air and started calling CQ POTA on the 20 meter band.

Within 10 minutes, I worked my first ten contacts thus securing a valid POTA activation.

I continued answering calls and added 26 more hunters to the logs.


My battery died!

Right as I was signing off with Mark (W7GCY). Thankfully, I was able to complete my contact with him, he just didn’t hear the last letter of my suffix as I signed off.

I can’t think of the last time this has happened to me: I’m pretty meticulous about re-charging my batteries.

I grabbed my simple N1JEO battery tester from my field pack and hooked it up to the Bioenno battery only to realize (of course!), the BMS completely shut down the battery. (Note that in the next field report and video, I’ll show how the N1JEO battery tester works.)

In the end, I logged a total of 36 stations in 41 minutes! I was a happy camper.


Here’s what this 5 watt activation looked like when plotted out on a QSO Map. You can tell that the 20 meter band was very productive, and just a bit short that day.

Activation Video

Here’s my real-time, real-life video of the entire activation.  As with all of my videos, I don’t edit out any parts of the on-air activation time. In addition, I have monetization turned off on YouTube, although that doesn’t stop them from inserting ads before and after my videos.

Note that Patreon supporters can watch and even download this video 100% ad-free through Vimeo on my Patreon page:

Click here to view on YouTube.


The in-line K9DP BCI filter

If I can hold onto the loaner G106 a bit longer before shipping it back to Radioddity, I’ll take it back to Fort Dobbs and deploy a 40 meter end-fed half-wave again. I’d like to hear the difference with the BCI filter in-line.

Back at the QTH, the BCI filter has effectively mitigated AM broadcast bleed through on the G106.

Post-activation, I realized that I had indeed used this same 3Ah battery with the G106 during a different activation–in other words, this was the second activation on one charge. Most of my other general coverage QRP rigs can do multiple activations on one charge of a 3Ah battery, but the G106 does use 2-3 times more current than, say, my KX2, KX3, or TX-500.

I contemplated grabbing my MTR-3B kit and 9V 3Ah battery from the car–I believe I mention this in the video–but in the end, I decided against it. I would have only been able to play radio a few more minutes before needing to pack up anyway.

Note that the G106 can operate down to 9VDC, so I’m guessing the fully-charged 9V 3Ah battery pack in my MTR-3B kit would have given me quite a bit more air time. It’s a good thing that the G106 has a fairly wide voltage range (9-15VDC).

Alternatively, I could have hooked up the MTR-3B to my 9V battery and played radio for a few hours longer. It uses something like 20mA in receive, 500 mA in transmit! It’s insanely stingy current-wise.

Thank you

As always, thank you for joining me on this activation!

I hope you enjoyed the field report and my activation video as much as I enjoyed creating them. I love this stuff!

Of course, I’d also like to send a special thanks to those of you who have been supporting the site and channel through Patreon and the Coffee Fund. While certainly not a requirement as my content will always be free, I really appreciate the support.

As I mentioned before, the Patreon platform connected to Vimeo make it possible for me to share videos that are not only 100% ad-free, but also downloadable for offline viewing. The Vimeo account also serves as a third backup for my video files.

Thanks for spending part of your day with me! Here’s wishing you an amazing week ahead! Go out there and play some radio if you can!

Cheers & 72,

Thomas (K4SWL)

11 thoughts on “POTA at Fort Dobbs: Testing a BCI filter and depleting a battery!”

  1. Beautiful site. After spending the night in Statesville I activated Ft Dobbs on March 14th with my xiegu x6100 . Yes it is a great site but don’t forget to go on the tour of the fort. Led by an enthusiastic historian it was one of the highlights on our trip to Hilton Head

  2. Tom- great report, and thanks for the reference to K9DP’s BCI filter.

    I’ve had issues with BCI here- a 5KW daytime station a little over a mile away. After fighting it for a while, I decided to TRY listening to it on the big doublet.

    The ‘receiver’ consisted of a diode and a 1K:8-ohm transformer. Ear-filling volume! My wife’s jaw dropped when she put on the headphones and I explained that there was no battery involved. 72- K1SWL

  3. FYI, just had my G106 delivered that day from Radioddity. I plugged it in, hooked up an antenna, and pulled up the POTA website. You were the maiden QSO for my G106!

    72, Clint

  4. EFHW (and other off-center fed) antennas tend to be more prone to BC interference and RFI effects by their nature, so it would be interesting to see if the filter is as effective with the EFHW next activation. My biggest problem with the G106 is (at least with my sample) its tendency for “ghost” images of stations to show up on secondary frequencies causing interference.

    73, Kevin K3OX

  5. Tom,

    Have you checked insertion loss on both receive and transmit? I have no issues with BCI, but it would make a nice accessory to take along when traveling.


  6. Great testing and report. I really wanted to like my G106. I had a handful of cw contacts with it but the low audio, lack of features, and tendency/ability to hear a lot of nearby stuff was just too off putting so I did return it and picked up a G90 for portable and low power/QRP stuff. The G90 is a really great portable rig. It’s not perfect, nothing really is, but it’s a great rig.
    I will add that the form factor of the G106 is very cool and was what made me pick one up. Regarding the G106 and battery demands, I found out by accident that it will actually run on just one 9v battery for a short period of time.

    I had entered in my ham call and then boxed it up to return it. And then as I was getting ready to return the box I decided I didn’t want my call in the rig memory. I had a 9v battery on a plug that fit the G106 on my desk and plugged it in. The rig turned on fine and I deleted my call. How long it would run I don’t know, probably not long, but…. for a short time in a pinch it’s an option.

  7. Nice report Tom. My experiece with the G106 showed it more suseptible to BCI on my end fed than my vertical. Polarization? But sure looks like you had fun.

    Pete WK8S

  8. I don’t know if it’s a polarization issue or something else, but this mirrors my experience with activating K-7954. The broadcast towers for WKRD are basically across the street from the park.

    My vertical, a Wolf River Coils TIA Mini with the standard three 10 meter radials, needs zero filtering. But the EFHW using a TennTennas 49:1 (highly recommended by the way) and speaker wires is a veritable RF magnet for the MW band. WKRD even bleeds through the contest grade front end on my Yaesu FT-710 on 40 meters with that antenna.

    1. I have a similar situation with local BC tower nearby. My end fed will suffer from it whereas my vertical does not. I have choke beads on the coax to no avail. A BCI filter at transceiver helps.

      Pete WK8S

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