Build Your Own 40M Band Pass Filter - Step-by-Step (#44)

[@W0KNI]

Have you built a band pass filter for your radio events? If so, what family of filter design did you use? I'm really curious to know! Cheers.

[@AndrewMurphy8383]

i have not built a band pass filter but have built something i seen online using dpdt switches and three resistor and it work to atturate

[@markusberg2770]

I’m happy with my two Chebyshev filters (7 pole) for 40M and 30M. Your construct appears to be of similar caliber to the DX product. Congratulations. 73

[@krisraps]

WOOW, Its So Cool To have Money ! You Can Buy And Build Stuff By Yourself,. Crazy !

[@rudyackerman5747]

Thanks for the video. I do a lot of POTA and these will be helpful when several operators work close to each others.

[@brianhoglan5913]

I agree with another comment down. The approach of showing the diagram updated live as you're building the circuit was super cool. Overall the production value in this video is staggering. Awesome work! I've been looking at the ARRL article you reference for a while coming up with a game plan to build the three pole version. Your presentation and method is so much more accessible, I'll be shamelessly copying your work here.

[@yakovrokhlin316]

Great video. I love it!!!!!!

[@W0KNI]

Glad you enjoyed it!

[@krisraps]

Your Videos Are lways Inspiring And VALUEBLE TO WATCH AND LEARN. :) I Wish I Could Do This Project, Make This Filter :( I Get Super Good Signals , But The Noise Is Just CRAZY ! I Cant Afford To Buy All These STuff And Even When I Tried To Substitute, Did NotW ork :(

[@krisraps]

BTW I have MANY , PLENTY Of Radio Components From USSR/Soviet Times, SUrplus, If You Want Anything, Let me Know :)

[@johnwest7993]

Thanks for the video. But actually, I was hoping to see the results of the filter build as shown on the NanoVNA. I've seen hot glue before. I'd like to know what the loss is with those Mix-6 cores and that gauge wire. What the bandwidth is. What the skirts look like. That's the nuts and bolts of a filter.

[@W0KNI]

Hey John. Did you watch at 14:40? I show the Nano results while adjusting the windings. It was used during WFD this year and held up to 100w without any trouble.

[@johnwest7993]

@@W0KNI, yes I did.

[@haraldlonn898]

Great video. I would build it like a U not a I as shown

[@melming8751]

What kind of pliers were you using to make the small loops at the ends of wires? That looked very interesting. Loved the video.

[@W0KNI]

Thanks for watching Mel. These are Bail making pliers amzn.to/40yGvSP

[@frequencywatchers]

What A Super Video, Im Wondering , I Have A Bunch Of Desoldered Toroids And Other Things Like Them pf Capacitors and diodes, how can i tell what toroid i have? what value on it? can i tell that by VNA or can`t? thank You

[@W0KNI]

Thanks for watching! Well sadly I ran into this problem too. If you have some color coding that can help, however I've not found a good source or method to discover the alloy mix. But you can always experiment!! Welcome to the hobby!

[@ozarktreasures8044]

Stephen, great video, very informative. I have been trying to wrap my mind around bandpass filters and your video really helped. I am not a Ham, but I do enjoy building Regen receivers and evesdropping on you guys. I have two questions: Will this filter work in a Regen, and if so, and since I won't be transmitting, could I get by with smaller toroid cores as long as the inductance is correct? Thanks.

[@W0KNI]

Ozark - thanks for the kind words! AFA the Regan RX, I don't see why not as long as the resistance requirements are met. AFA the size of the toroids, I would have a hard time getting the required number of windings for anything smaller. Sounds like a fun project! Cheers.

[@TheSmokinApe]

Fantastic video Stephen, really enjoyed this one 👍

[@W0KNI]

Glad to hear it Ape! I appreciate the feedback. This was certainly a learning project and now with all the spare parts I plan to build a 20m soon. That VNA always impresses me. Cheers!

[@krisraps]

6:03 - Meow!

[@frequencywatchers]

This Video Is So Valuabble, So Much Tricks And Tips That I Noted, Thank You Very Much. By The Way, Do You Want Any of My USSR Surplus Device Parts And Components? :) I Have Videos On It, Just Answer My Comment If You Want Them, Il Send You A Private Video Link And You Will Se What I have :) I Have Military Grade USSR Surplus Devices AND Parts For Radios !

[@MickeyMinutes]

Thanks for the detailed video. 73 N4ETM

[@W0KNI]

You are welcome! It was a fun project and I hope to build another before our next field day. Thanks for watching!

[@lovelycollection100]

What about insertion loss

[@W0KNI]

Was all that good honestly. I built this to understand things and it's still being used during group events and works well. However your best bet is from the Russian company Low Band Systems. There are a few US distributors you can grab them from. I own and have tested their 20M BF and it has an amazing drop off and low insertion loss.

[@lovelycollection100]

​@@W0KNI i Made in toko AND toroids but all hace Lot -db 7 AND 10 i see this banda pasa hace .2

[@arnoldcabahug6873]

Hi Stephen. i used a linear amplifier on to my radio, is there any issue attaching this Bandpass Filter before the linear amps? (Radio-Bandpass-Linear), appreciate your reply 73!

[@W0KNI]

Hey Arnold - thanks for watching! Boy, good question. Honestly I don't have any experience with that configuration. The BPF is for received signals, so the TX wouldn't need it. The parts I used in the video would NOT support much over 100w. Sorry I can't answer that for you.

[@justinelliott3529]

Those leads are extremely long. But it’s an amazing video!

[@HighFidelityFox]

Very nice video Steve. I’ve been wanting to get a band pass filter so I can do POTA with a friend, 20m/18m split. However, this looks too complicated for me to do so I think I will just have to buy a pre made one

[@W0KNI]

Thanks Zzyzx. I admit it was a lot of work and research to do but it was one of those learning things I wanted to do. And honestly for the price of about $125.00 you can get a really nice retail solution. Have fun and thanks for watching!

[@paulb9179]

Anyone know what that red compound is on the Low Pass Systems filter on all the ezposed wires? I am assuming it's some kind of liquid insulation so as to keep stray magnetic fields at bay.

[@W0KNI]

I'm pretty sure it's just liquid tape

[@JaySteiner]

I started looking for homebrew filter videos and stumbled across this one... Holy smokes! Great video. I really like how you show the solder points on the diagram in realtime as you are going along with your project. Its probably the first time I've seen someone do that and it was really quite helpful.

[@W0KNI]

I'm so happy you enjoyed the video and found it helpful Jay. I was like you, searching and searching but didn't find exactly what I was hoping for. So, since I had the resources to make a video I figured I would take the time and document the best I could. I've used this one a few times and it works as expected. There's always room for improvement, but hey that's what's fun about this hobby. Cheers!

[@rfdave3980]

Hi precision LC Meter ? Yeah right... don't think so. Enjoyed the video thou

[@W0KNI]

The model I show isn’t too expensive but if you’re only going to use it for a project like this then I would suggest just buying a commercial filter and forego diy project

[@jimpainter9935]

Why are you using two different size toroids?

[@W0KNI]

Hey Jim - thanks for watching. The different sizes allows you to have more or less windings to achieve the inductive levels you need.

[@DK5ONV]

Awsome work done. 73's de Your Friend Uncle Guenter

[@W0KNI]

Thanks for watching 👍 Guenter!

[@DK5ONV]

@@W0KNI you welcome

[@Terribleguitarist89]

Killer video quality and production

[@W0KNI]

Thanks! Glad you enjoyed it. And that thing actually performed well during field day this year. Cheers!