As I’ve previously mentioned, the Xiegu X6100–at least at time of posting (January 17, 2022)–has overloading issues. If you listened to the activation video I posted yesterday, you can hear a local AM broadcaster punching through the 40 meter band, especially noticeable before/after operating SSB.
Several subscribers asked if I tried using the attenuator and RF gain to mitigate the level of overloading. Attenuators and RF gain can be an effective means of mitigating noise levels, but they essentially affect everything on the band–all signals somewhat equally.
A better approach is to use a BCI Filter.
BCI Filters
BCI filters reduce or notch out AM broadcast band signals so that they don’t overload your receiver.
BCI Filters are placed between the radio and the antenna. They can have a dramatically positive effect if you live near a broadcast station and/or if you have a radio that’s prone to overloading.
I see them as a more “surgical” approach to solving broadcast band interference.
BCI filters are simple, inexpensive, and effective. Here are two options shared by QRPer readers:
BCI Filter: Homebrew Option
Many thanks to Rich (KQ9L) who notes that his Altoids Tin homebrew BCI filter works amazing well with the X6100. Rich writes:
Thomas, I’ve attached a picture of the QRP BCI filter I built prob close to 20yrs ago. It is a must at my QTH where the “Score” a megawatt am station is within 10 miles of me.
The X6100 in my setting is not usable without the filter.
The attached videos show with and without the filter monitoring a CW QSO. You can see the time on the radio to confirm they were filmed approximately at the same time.
X6100 without the BCI filter:
https://vimeo.com/666741947
X6100 with the BCI Filter:
https://vimeo.com/666742181
Rich couldn’t find the exact plans for this particular BCI filter since it had been so long since he constructed it, but he pointed to this article for reference.
Thank you so much, Rich for sharing this.
Note that BCI filters are also available as kits. You can find them for as low as $5 and they’re quite simple to build; they will require winding a few toroids. Simply do a search for “BCI Filter Kit” and you’ll find several results.
Make sure you’re purchasing a filter kit that can handle a transmitted signal. This is typically indicated in the description.
If you’ve recently built a BCI filter (homebrew or kit) please share details and links in the comments!
BCI Filter: Off-The-Shelf Option
Our thanks to Dennis (K2DCD) who writes:
[Check out this] BCB Transceiver Filter for $42. Scroll down to the bottom of this page. ICE products are built like tanks and should fix that problem with the Xiegu.
https://www.iceradioproducts.com/filtersrf.html
[Note: Since publication, it appears ICE is no longer in business.]
I know shortwave listeners who swear by their ICE filters and I agree that they are excellent quality.
Of course, make sure you’re purchasing either the Model 400X which attenuates everything below 3.5 MHz, or the Model 402X which attenuates everything below 1.8 MHz. Both are $42.00 US. The other models are less expensive, but designed for receiving only.
Many thanks again to Rich and Dennis for sharing their tips! Please comment with details if you use a BCI filter at home and/or in the field.
Ice filter for bci issues use the ones that have x on end of model number, these are for xcvr’s 300 watts. Non x on end are rcvr only. 73 john
I found this site in my searches for the good BCI Filter. Seems that Ice Radio Products website is not working at this time.
In my searches I found that iceradioproducts.com site is not working, however, same filters can be ordered from https://surgestop.com/filter-products/index.html site.
Also, https://vk3il.net/projects/broadcast-band-filter/ can be built into altoids, or similar box. Haven’t done it myself yet, but probably will
Thomas:
After using the website to try to buy a $38 filter for 20m and failing I reached out directly to the company. These filters have been replaced my new models – that list for about $140.
Oh wow. That’s a huge price jump.
Hi Thomas, thanks for posting this. Yes the filter is essential at my home QTH, you can see the massive interference from the AM station which overloads the receiver. If you noticed the ATT is activated and even with attenuation the receiver is overwhelmed. The filter I built is only for QRP levels and I’ve worked the x6100 through this fillter to 10w SSB, but only 5w CW. I tried an inexpensive band pass filter one from Amazon and this little filter works much better. When I get home from work, I’ll take some close ups of the filter and see if I can find the capacitor values.
I dont have overload issue from a near by radio stations, but do have bandpass filters for 10, 15, 20, 40 & 80m I use at Field Day. They can handle 100W so good for both xmt and rcv.
I had one box with 6 bandpass filters inside with switch on front and relays inside to select the filter needed.
These filters can be very useful for many Ham activities, but have not had issue at a POTA or other similar event.
73, ron, n9ee/r
” It is a must at my QTH where the “Score” a megawatt am station is within 10 miles of me.”
I think WSCR is 50 kW, or 0.05 MW. Currently FCC does not allow AM stations in the USA to run more than 50 kW. (Once upon a time WLW, near my home town of Cincinnati, ran 500 kW.) But even “only” 50 kW is a blowtorch.
There are a few AM stations in other parts of the world running between 0.1 MW and 1 MW, but I don’t think there are any more powerful than 1 MW.
Of course for CW, 5 W is usually plenty ;-).
David VE7EZM and AF7BZ
Yes, 50kW is limit since the 1940’s or so, maybe earlier. Most of the near-or-at-MW class are in Region 1 (EMEA), more rarely in R3 (SEA & Oceana), but there are a small number here in R2 (Americas), and I believe Radio Marti on 1180 in Marathon, Florida is like 100kW+ but as it’s a propaganda rather than commercial station, I don’ t know for sure.
I mentioned this in my comment on the X6100 vs IC-705, but here in Phoenix, Arizona there are numerous stations 10-50kW, some remaining at 5kW+ at night. These destroyed my attempts to listen with my FT2DR and TH-D74a HTs with an amplified antenna, and it would seem the X6100 would be the same, making it useless unless quite a distance out of the city.
What about simply backing off the RF gain?
It can be surprisingly effective.
G7VFY
That would have the effect of decreasing ALL signals, not just the interfering BCB station(s). Hence filtering out BCB and leaving the remainder of the spectrum at normal reception levels. As Thomas says, this “surgical” method is best to excise the bad while not touching the good.
You said
“Attenuators and RF gain can be an effective means of mitigating noise levels, but they essentially affect everything on the band–all signals somewhat equally.”
My reply:
If the spurious response is due to non-linear overloading of the front by the strong broadcast station, then any thing that reduces the broadcast signal, jncluding increasing the attenuator or turning off the preamp, will help dramatically. That’s why the manufacturers make them switchable. In this case, the broadcast station is coming through because the receiver’s mixer topology has an inherent response to odd harmonics of the input signals. For instance, if a strong station is at 1010 khz, the 7th harmonic falls on 7070 khz and will be heard. I measured this particular response and sensitivity to it is about 50 dB lower than an on-frequency signal. So a highpass filter is the proper fix in this case.
At this time I have not experienced an overload with the X6100 buttons I can tell the receiver is very hot. I live in Pittsburgh about 15 air miles South of KDKA’s 50,000 watt blow torch as they used to say. So far I don’t see anything like you are experiencing. I suspect that if I were closer to the city things would be different. I’ve read where a few people have suggested the obvious of backing down the RF gain. I suspect these are people that don’t own an X6100. You can run the RF gain all the way down to 10 which is the lowest that it will go on the X6100 and still not clear up the waterfall like you can do with an IC-7300. Despite this I am still very happy with the radio. It still needs some work via firmware but I have faith that it will get there. Maybe not the overload issue but the other issues.
I looked around for a BCI filter. This site looks like it may have a contender. https://shop.kit-projects.com/index.php?route=product/product&path=59&product_id=118
And, this looks like a “ready to use” filter:
https://www.ebay.com/itm/294949503400?var=0&mkevt=1&mkcid=1&mkrid=711-53200-19255-0&campid=5338590836&toolid=10044&customid=8e73f7c8493b1bdf04e3945daafe7985
ICE Radio Products appears to have closed their website. You may want to remove the link.
Done! Thank you!
There were no video’s. Could you share the specifics on the coil and values of capacitors.
7f3
Mike W2HLD
[email protected]