Homebrew Bandpass Filters for Ham Radio

[@HOAHamRadio]

Where do I log my CE credits, and when do I get my certificate of completion? You demonstrate for us all, we have a lifetime of learning / accomplishment / enjoyment ahead of us. Thanks Ape!

[@TheSmokinApe]

Hey Bob, thanks for checking out the video bro! Wen you making one?

[@HOAHamRadio]

@@TheSmokinApe Ah, um, well, hmmmm; I think I need to learn how to use my Tiny SA first. I'm getting closer; may hook the Tidradio H8 up to it and give it a go.

[@KK6USYHamRadioAdventures]

Nice build Ape, we need to look deeper into these!

[@TheSmokinApe]

Thanks Chuck and yes we do 👍

[@Ezzell_]

Great video...no fluff....under 10 mins....nice.

[@TheSmokinApe]

Thanks Ken 👍

[@Bill-HRT]

Thanks Ape! I love this kind of project. You just plain talked the confusion out of the articles I see. 73 de Bill

[@TheSmokinApe]

Thanks Bill, I appreciate you checking it out 👍

[@robertmeyer4744]

great build ! very handy to have. no need to run an amp threw it. the output section in a amp has a filter. you want this on radio side to help with receive. strong signals out of band can over load the RX . also can really help with out of band noise. 73's

[@TheSmokinApe]

Right, it's more important on RX. Thanks for watching Robert 👍

[@KS0JD]

Nice build Ape! The trick to any RF work is short leads and good ground plane. The higher the freq the closer the components are together. I think you will see a change in the performance if you use a copper clad pcb. You could probably have PCB way build you one pcb that would work for all the filters. For best results would be to do a active model of the board with a filter. Don't know if PCB way has modeling software for this. Tools like Mathlab or Spice come to mind but it has been a few years since I did any of that. They have probably all changed. Good luck! 73

[@TheSmokinApe]

Thanks man. I do think the GP on this one was a little janky leading to the goofiness on the lower side. I'm thinking about getting a board from PCBway for future videos.

[@youtubeaccount931]

Nice caps! Always on the lookout for those

[@TheSmokinApe]

They are a bugger to find

[@jameski5oeb668]

Thanks for putting this out there!

[@TheSmokinApe]

Thanks for watching James 👍

[@MikeN2MAK]

Some of this is a little above me or intimidating, but I could make use of some bandpass filters. Thanks for another good one. This could be helpful for me down the road.

[@TheSmokinApe]

Thanks for checking it out Mike 👍

[@technishn]

It looks a bit strange on the LF side? Does an Elsie filter simulation show that?

[@TheSmokinApe]

I didn’t model it, I was thinking the cores were bleeding over or it was my janky ground plane 👍

[@technishn]

@@TheSmokinApe I modeled it using Elsie, and it it didnt show any LF aberration, so probably the meandering ground. I buy 5 x 7 cm double sided copperclad PCB.

[@TheSmokinApe]

I used the copper PCB on the first version, I was just "prototyping" the components in this video for experience. I expect that I will do more BPF videos in the future... thanks as always for the comments 👍

[@DonzLockz]

I would only need to build one if the radio didn't already have one onboard, right?

[@TheSmokinApe]

People will use them in addition to the built in BPFs if they are operating in an RF rich environment where they get interference. The prime example would be Field Day when there are other hams operating close by 👍

[@DonzLockz]

@@TheSmokinApe oh damn, I didn't know it could be that bad. Great info Master Ape!👍😁

[@TheSmokinApe]

Thanks for watching Don

[@temporarilyoffline]

Always improving!

[@TheSmokinApe]

I gotta figure out a pcb design to make this easier

[@tomstrum6259]

Maybe you help me with BP filter builds....I've used regular Diy 16 ga Air core Inductors + Mica caps in Partitioned-Off Enclosures for all my Hf Filters with No issues....The relatively Large gauge enameled Wire is so Easy to cut & Squish or Push turns together to Precisely Tune filter sweep Characteristics......Why use the messy & Questionable Toroidal core inductors when Air core work Fine ??

[@TheSmokinApe]

It's my understanding the air cores are more subject to leaking and require shielded separation. While I'm sure its still in issue on toroid wrapped cores it's less of an issue.

[@kevinkc3onohelijeepworld]

Nice filter ape 🫡

[@TheSmokinApe]

Thanks Kevin!

[@thuff3207]

Nice job of building a filter. I would suggest watching your phase if you use this on digital transmission.

[@TheSmokinApe]

Thanks for the heads up Thuff 👍

[@JT-py9lv]

Thanks Ape... I'm on the hunt for Type 6 toe-roids now. I've found some T200's... Humm ??? With some 14awg magnet wire.

[@TheSmokinApe]

I think I got these off Amazon 👍

[@FEPLabsRadio]

Damn fine job, son!

[@TheSmokinApe]

Thanks FEP 🍻

[@mstover2809]

In Figure 4 (The chart for the 5 pole filter) the input and output values are the same, whereas the L3 inductor is 1/2 L1 and C3 is 2x C1. DLd the .pdf to see it for myself and checked the 5-pole filter in Fig 4.

[@TheSmokinApe]

Thanks man 👍

[@Thump2030]

Good video Ape

[@TheSmokinApe]

Thanks Thump 👍

[@JayN4GO]

Well done

[@TheSmokinApe]

Thanks Jay 👍

[@Swamp-Fox]

Is the power handling capability determined by the core size, magnet wire diameter, and voltage rating on the silver mica caps? How about a Chebyshev vs Butterworth comparison for a future video. Great stuff!

[@TheSmokinApe]

To answer the question, I'm going to say "yes". I do believe all of those things play a factor. I do expect to be playing around with these filters more in the future so maybe I can add the other design. Thanks SF 👍

[@don_n5skt]

When you say 100W capacity, is that 100W FT8?Also, where in the chart can we find 12m and 30m ;)

[@jamess1787]

Last comment got nuked. Online calcs are our friends. Nice thing about the community: lots of brilliant minds who put all the hard work in for the rest of us to benefit from. 🤜🤛

[@TheSmokinApe]

It might do it for FT8 but I'm sure the designer was using ssb. I don't have a chart for 30/12 yet... lol

[@jameshall5835]

I plan on doing this filter in a slightly different way. I’m going to try Manhattan style construction using small islands (min capacitance) and have an uninterrupted ground plane. It will be mounted with metal standoffs to make the box continuous with the GP - eliminates the need for a separate ground strap from the connectors. As POTA becomes more popular, multi-op is inevitable. So trying to stay ahead of this ! I recently repaired a couple BPF’s after a major RTTY contest. These are Chebyshev type however. Always sumthin’ ! 73 Jamie WB4YDL❤

[@TheSmokinApe]

He James, I actually have a new filter in the works. The video should be out soon. Sounds like to have a cool project planned, best of luck with it 👍

[@jameshall5835]

It came out well - be glad to share it. The videos are long because it’s blow by blow walkthrough. I have Parts 1 & 2 in my Dropbox. The spec an shows it dead on first try !

[@Frank_K4FMH]

Good followup! Note, again, how Gordon mounted the toroids at explicit right angles to one another! You might re-jigger yours and re-sweep. The lower skirt might improve. 73 de K4FMH

[@digitalradiohacker]

I've had minor cross-talk between transformers mounted on a PCB before. Turning one of them 90deg from the other totally eliminated the problem.

[@Frank_K4FMH]

Roger! Note too the original QST article figure: they are shown at right angles to one another. The author didn’t explicitly mention this, as I recall.

[@TheSmokinApe]

I’ll mess with it a bit, thanks for the heads up

[@Frank_K4FMH]

@@TheSmokinApeIF this adjustment does improve the skirts, it would make a great and informative video for other builders to illustrate how the physical isolation by making the toroids at right angles helps. $0.02

[@TheSmokinApe]

👍

[@tomstrum6259]

For Any effective RF filter, Using a too Small Enclosure with components (Especially Inductors) jammed up Close despite core Orientation is asking for Needless coil to coil inductive Cross-Talk & undesirable signal Leakage Coulping....It's just HF but Using a Large enough Enclosure with Isolating Each filter "Pole LC pair" components into RF Shielded partitions can get results Closer to the Model specs...

[@TheSmokinApe]

Hey Tom, the design I followed called for the use of this enclosure but I don't disagree.

[@DutchmanRadio]

This is epic!

[@TheSmokinApe]

Thanks RO 👍

[@donepearce]

Please use return loss instead of VSWR. It contains the same information, but presents it in a far more useful way.

[@ZeroHarry]

My opinion, your original one looks more better to me, maybe just a little more heat on the joints to get better flow.

[@TheSmokinApe]

Thanks Zero 👍

[@germanjohn5626]

3db loss means you lose 1/2 of your power, good luck running any power through it. It will burn up in a flash with 100w and 50w of it turn into heat. Touch a 50w solder iron and see how hot it is.

[@LeeMcc_KI5YPR]

Pretty sure its not 500kV? That would arc a few feet. Is there a video? 🤣 Regarding the unbalanced filter plot, I suspect one of the inductors has a parasitic property due to difference in windings.

[@TheSmokinApe]

Yeah, the 500kv surprised me. I do think you are right about the cores or it might be my janky ground plane 👍