BCI Filter Kits K9DP vs N4ELS
Preliminary:? Showing only the nanoVNA marker data, more details to come later.
K9DP????????????????????????????????????????????????????????????????????????????????????? N4ELS
 ? ? ? ? ? ? ? ? ? ? ? ? ? ?  ??????
Compare S21 Gain at Marker 1 and Marker 2:? ~.55 MHz to ~1.6MHz
K9DP -45.8dB to -2.36dB??????????????????????? ? ? ? ? ? ? ? ? ? ? ? ?? ???? N4ELS? -73.7dB to -40dB
Recall that -30dB is a factor of 1000 and -40dB 10,000
AKA K9DP BCI HP Filter kit????????????????????????????????????? AKA QRPme BCI HP Filter Kit
 ????????????????????  ?
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Re: Buildathon Sea Sprite+ builders - are you out there?
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Show quoted text
On 04/16/2023 7:25 PM Josh Kesecker <joshnfamily@...> wrote:
3 of us built it, with 2 getting on the air, and hearing each other 18 miles apart.
I've made a contact, joined the group, & hope to make the mods.
4 more waiting for schedules to line up to do a build too!
On Sat, Apr 15, 2023 at 6:58?PM Daniel KK4MRN via <SQLDan2000= [email protected]> wrote:
Hello all,
So, did any of you build the Sea Sprite+ transceiver, still working on it, or plan on building or buying it?
Did you recently join this QrpmeKits google group?
Please talk about It.? I want to hear from others.? ?Some of us who got our Sea Sprites can help you.
I still need to do the mods for the audio and BCI filter and add the switch to bypass the no tune coupler or point H for a 50ohm antenna.? Currently, it is hard wired to use the 50ohm antenna on point H which I used to measure power output via a 50ohm power meter and dummy load that can display QRPp and QRP power levels.
I am interested in learning how to use an RF Probe or tracing probe to see what is going on in the radio on receive or transmit.? ?See the output on my used oscilloscope or my TinySA spectrum analyzer or other tools to measure with.? Any recommendations?? Whatever i do, i want to write it in a notebook, draw some graphs or circuits on some graph paper and make notes.? I may take more photos and create a video of it operating and upload to YouTube but need those mods done first.? Still learning Morse code and hopefully I can Get on the air on May to make contacts using the little radio.
Any others still learning morse code?
73 Daniel KK4MRN
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Re: Buildathon Sea Sprite+ builders - are you out there?
3 of us built it, with 2 getting on the air, and hearing each other 18 miles apart. I've made a contact, joined the group, & hope to make the mods. 4 more waiting for schedules to line up to do a build too!
On Sat, Apr 15, 2023 at 6:58?PM Daniel KK4MRN via <SQLDan2000= [email protected]> wrote: Hello all,
So, did any of you build the Sea Sprite+ transceiver, still working on it, or plan on building or buying it?
Did you recently join this QrpmeKits google group?
Please talk about It.? I want to hear from others.? ?Some of us who got our Sea Sprites can help you.
I still need to do the mods for the audio and BCI filter and add the switch to bypass the no tune coupler or point H for a 50ohm antenna.? Currently, it is hard wired to use the 50ohm antenna on point H which I used to measure power output via a 50ohm power meter and dummy load that can display QRPp and QRP power levels.
I am interested in learning how to use an RF Probe or tracing probe to see what is going on in the radio on receive or transmit.? ?See the output on my used oscilloscope or my TinySA spectrum analyzer or other tools to measure with.? Any recommendations?? Whatever i do, i want to write it in a notebook, draw some graphs or circuits on some graph paper and make notes.? I may take more photos and create a video of it operating and upload to YouTube but need those mods done first.? Still learning Morse code and hopefully I can Get on the air on May to make contacts using the little radio.
Any others still learning morse code?
73 Daniel KK4MRN
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Re: Some BCI Filter Notes
Thanks Chuck, I have some 26 gauge I will try, no 24 in stock here it seems.
On Sun, Apr 16, 2023 at 7:26 AM, Chuck Carpenter <w5usj@...> wrote: Davey,
I used #24 for a T37 core for up to 25 turns (~1.8uH).? MRCC has that feature...8^)
Although I think it overstates the wire size.? For a T50, #22 works OK.
Even if you have only a few turns, #22 is a little stiff for the small core
and hard(er) to mash it tight to the core for best coupling.
In a pinch, calculate the core inside circumference. Measure the wire dia.
then figure the number of times it will fit.? TIC, of course...
I'll have to check the info from Diz, Like you, I think of seen that someplace.
Just don't recall where.
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Re: Photo of my Sea Sprite+ in my ham shack
W4RNL was not a G5RV enthusiast. He said, "just bring the balanced line all the way to the tuner and forget the coax matching section".? He made several disparaging comments about it in numerous articles.? Strangely, every G5RV op I have had contact with had very strong signals at QRP.? I never have built one but the concept was interesting.
We ought to spend more time on our antennas than on our rigs I suppose.? Less expensive and more productive.
Curt KB5JO
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Re: Photo of my Sea Sprite+ in my ham shack
Curt,
I was thinking that but that was a while ago. Mine got torn down when a guy mowing my yard got hung up in the rigging.
I called the 44ft extended dipole a 20 meter antenna as was the 52ft Varney, G5RV, version. Varney did his to get the 20 meter major lobe to line up with his long narrow plot. Don't recall the direction but it was along the axis of the dipole**. With the 44 ft it is the opposite with the major lobe perpendicular. An EZNEC model shows the difference with the 52 ft having fairly broad major lobes.
**I found the original article from 1958.? Amazing work and he didn't have the latest copy of EZNEC...8^)
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Re: Some BCI Filter Notes
Davey,
I used #24 for a T37 core for up to 25 turns (~1.8uH).? MRCC has that feature...8^)
Although I think it overstates the wire size.? For a T50, #22 works OK.
Even if you have only a few turns, #22 is a little stiff for the small core
and hard(er) to mash it tight to the core for best coupling.
In a pinch, calculate the core inside circumference. Measure the wire dia.
then figure the number of times it will fit.? TIC, of course...
I'll have to check the info from Diz, Like you, I think of seen that someplace.
Just don't recall where.
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Re: Photo of my Sea Sprite+ in my ham shack
On Sun, Apr 16, 2023 at 02:16 AM, Chuck Carpenter wrote:
88ft dipole fed though an MFJ-969 tuner
Was mine as well.? I always thought of it as a CF Zepp for 40M.? Fed with MJF Tuner using RS twinlead.? Worked on 10-40.? I am using a 176' CF Doublet now fed in the same way.? And a 40M FW Loop also fed with twin-lead.? I always thought W4RNL was a legend.? His "5 backyard antennas" article was my bible. Curt KB5JO
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Re: Photo of my Sea Sprite+ in my ham shack
John,
Thanks, that was a bit of "tongue-in-cheek" about not understanding point "H" and etc.
With the v6 I'd built before the VideoCon, the no-tune was never used. I know they work, up to a point **,
but they just don't make sense to me.? The tuneable transformer from AA5TB works a whole lot better.
Not much room to fit into the coupler space though.
For testing otherwise, I attached an SMA jack at the end of the LPF doing the evaluation at 50 Ohms.
The only antenna I have left now is the Butternut vertical and it's "tuned" for 80 to 6 meters more or less.
The nanoVNA showed me I didn't do quite as good a job as I thought using an MFJ-259. Or maybe it's
been out there for 25 years and it needs a good D&C...8^)
For many years the main antenna was a W4RNL, 88ft dipole fed though an MFJ-969 tuner, 160-6 meters.
160m with the feed point shorted and fed like a top-loaded long wire. Worked, sort-of. It broke and I don't
have the wherewithal to fix it.
** Some bench testing with a signal generator and O'scope provided data on what the no-tune would do
with various load impedances. Conclusion was: Not so Good.? Much better with the AA5TB tuneable coupler,
The bench test lash-up for sig gen; coax choke balun, 3el LPF, 10dB Atten to force 50 Ohms to coupler link.
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Re: Photo of my Sea Sprite+ in my ham shack
Hello Chuck,
I am glad you asked!
John already replied about point H.? So, I will not go over that.? ?But I am so glad he emailed others what he did with point H.? This helped me.? ?
Sadly, there is no documentation for the Sea Sprite+ unless you look at the videos, old documentation from the Sea Sprite, schematic and photo of its layout.
I did sort the parts on a piece of styrofoam before the buildathon.? But it took me through the rest of the night to finish it.? When winding the coils, I made sure the wires had the coating scapped off with a knife.? Then I used a multimeter to do continuity test to make sure it worked.? (To others reading this - this is stuff Chuck already knows how to do, but I go in detail for others reading this).? ?Then like Rex said, only put the coil in the pcb as a dry test.? Double check you did things correctly - winding, putting it the board.? Do another continuity test.? Others may not need to - but I had many projects fail so I want to make sure I do everything correctly.? ?Then I solder the wires.? And then I do a final continuity test.? Since the multimeter uses DC for the continuity test (I think), you should hear the buzzer on the multimeter since a coil will not block DC.? If you did not hear the buzzer, maybe you did not scrap enough coating off the ends of the wire.? Or your soldering job was not good.? ?The transformer was the hardest coil, but still doable.? There are no taps.? There is only one primary and one secondary.? ?So, not too hard.
Chuck, honestly, I'd rather read a build instructions document than watch a video.? But there was no document for the Sea Sprite+.? There was the documentation for the old Sea Sprite which looks good.? ?There is no doc on the NO TUNE coupler or how to bypass or any mods.? The only way to get that info is to have been part of the Buildathon (the presentation on Saturday and the follow up on Sunday).? I missed the follow up on Sunday.? Or watch the videos when they showed up on QSO Today a week later (only up for 30 days).? Or watch the videos from QRPme web page.? Or get the info from the private emails.? I wished the emails were part of the group.? ?
When I use my end fed random wire antenna with a 9:1 unun at the antenna, the impedance is still too high depending on band and frequency.? However, it is low enough for an auto tuner built in a radio to find a good match.? Or use an external antenna tuner.? Yet a QRP radio, I will need a z-match.? ?Some say I should use an end fed half wave or a OCF dipole, but they are too long for the bands I want to use in my yard.? While an end fed random wire and 9:1 unun with counterpoise I can get on 160m, 80, 40, 20, 17, 15, 12, 10, and 6meters.? Yep - 160 and 6 meters I have made contacts.? ?I only have one big tree which is at the fence of my neighbors.? And the other side has power line overhead.? So, no antennas can go near that side.
I am not about to change my end fed random wire antenna and 9:1 unun.? It took awhile to get it up in a tree of what I wanted via a Notch Big Shot.? The hard part was making sure it did not go into a neighbors yard.? ?The antenna is in back. My ham shack is in front.? So, the coax has to be routed around the house and through a Comet window feed thru.? Not the best situation but you do what you can.? ?Plus, where the coax connects to the 9:1, is wrapped with coax sealant.? So, it's not like I can disconnect it and hook it up to another antenna.? Not being snarky here.? Sorry.? ?So, I plan on operating the Sea Sprite+ from the back porch and use the included wire from the kit for an antenna thrown in the same tree which will use the NO TUNE coupler.? Or a shorter tree at the back porch.? Since we are talking QRPp power levels, it will be safe but the tree may not be high enough.? I live on a hill sloping down so this may affect my antennas.
I worked a 160m contest one night on my back porch and made 9 contacts.? Nothing like walking around in the twilight in the backyard laying counterpoise wire throughout the yard...? ?But a ham has to do what he has to do - to get on the air and make contacts...? ?However, the counterpoise cannot stay on the ground due to lawn needs to be mowed time to time.? So, I do need to bury the counterpoise, etc.? ?Also, my end fed random wire is 100 feet long, counterpoise is 100 feet long, and the coax is 100 feet (maybe 150) long.? ? The antenna is a thin inverted V in the tree.? ?A longer wire would not work.? Which is why I think an end fed half wave for 40meters might work: 66 feet which is what I thought the antenna we were going to build for the Sea Sprite+ was.?
As for the mod for the crystal.? I did it at the time I soldered the crystal to the pcb.? I used a discarded lead from a resistor that I snipped after soldering it to a board.? ?And the missing capacitor, I grabbed one from my junk box.? It was a cap I got from digikey or mouser which are the only places I buy my capacitors these days.
When I hooked the radio to various power meters via the antenna connector which uses the NO TUNE coupler, all the power meters and peak detector gave strange results.? When John suggested I use point H and hooked the radio up to my 50ohm power meters/dummy load or 50ohm peak detector/dummy load, the readings made sense.? The main reason I wanted to check the RF power output was to make sure the radio was really working...? When I transmit, I can hear it on my QRO radio and see it in the waterfall.? So, I know the oscillator is working...? ? But I needed to know if the power really was getting out there...? I probably could pound my call sign to see if the RBN (Reverse Beacon Network) picks it up.? But I am not in a place to make contacts yet - still learning morse code.? ?
Anyways, not sure you read this long boring email.
I wanted to say I am so glad that the radio works.? ?And it was really nice to be able to build it at the same time others built it.? ?One day, hopefully I get to the point to make contacts with others on 7110.?
73 Daniel KK4MRN
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Buildathon Sea Sprite+ builders - are you out there?
Hello all,
So, did any of you build the Sea Sprite+ transceiver, still working on it, or plan on building or buying it?
Did you recently join this QrpmeKits google group?
Please talk about It.? I want to hear from others.? ?Some of us who got our Sea Sprites can help you.
I still need to do the mods for the audio and BCI filter and add the switch to bypass the no tune coupler or point H for a 50ohm antenna.? Currently, it is hard wired to use the 50ohm antenna on point H which I used to measure power output via a 50ohm power meter and dummy load that can display QRPp and QRP power levels.
I am interested in learning how to use an RF Probe or tracing probe to see what is going on in the radio on receive or transmit.? ?See the output on my used oscilloscope or my TinySA spectrum analyzer or other tools to measure with.? Any recommendations?? Whatever i do, i want to write it in a notebook, draw some graphs or circuits on some graph paper and make notes.? I may take more photos and create a video of it operating and upload to YouTube but need those mods done first.? Still learning Morse code and hopefully I can Get on the air on May to make contacts using the little radio.
Any others still learning morse code?
73 Daniel KK4MRN
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Re: Some BCI Filter Notes
On 2023-04-15 8:23 a.m., David Knapp via groups.io wrote: There has got to be a chart somewhere telling me how many turns is the maximum per wire size on some of these various toroid sizes. Here is a recipe (not a chart). (1) Take the INNER RADIUS of the toroid. From that subtract the Diameter (not the radius) of the wire you intend to use. This will give you the RADIUS of the circle hitting the insides of all the turns. (2) Take that new radius and multiply by 2 Pi. This will give you the CIRCUMFERENCE of the circle hitting the insides of all the turns. (3) Divide that circumference by the DIAMETER (not the radius) of the wire you intend to use. This will likely be between two integers. Round down to an integer. That's the maximum number of turns that will fit. Actually if you draw a picture you will see that this is a (slightly) conservative estimate because you probably could have used the circumference of a circle passing through the centres of the insides of the turns, not the circumference I described above. Better safe than sorry, but with practical wire sizes it will make little difference. David VE7EZM and AF7BZ
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Re: Photo of my Sea Sprite+ in my ham shack
You CAN put a crystal set or a regen in a metal CAN (or box, haha). In fact, a regen probably should be in one, as should just about anything with an oscillator or that is very sensitive to outside influences (temperature/RF/etc, although metal isn't necessarily the only/right material for temp issues). Luckily, most of the radiation from a local oscillator is, well, local. However, a regen/super regen CAN radiate out into the ether via the antenna. That's why sometimes you'll see an RF amp in front end for isolation.??There's a similar issue with backwave that happens if you leave a transmitter oscillator running all the time instead of keying it, which isn't a problem with most simple transmitters (everything gets keyed).?For harmonics, though, a good output filter is important for transmitters and shielding can help with some maladies, again, I suspect, with mostly local issues at QRP and QRPp power levels. Receivers benefit from shielding, although there may be a point of diminishing returns. I think most, if not all, of the QRPME stuff is fine without additional shielding as it works well within expectations of fun, easy-to-make, straightforward, simple, usable kits that can be mastered by the average Ham. Heck, even my beloved Elecraft K1 has its shortcomings, and it's orders of magnitude more complicated than most things I build these days.?
As for crystal sets, I rarely use a bcb loop antenna. I like FT-114 toroids. They make a nice coil with relatively few turns of magnet wire with good enough "working" Q (I have never measured it) that I have been able to separate 10kHz stations. Toroids don't need shielding, but that also works the other way-- it won't be influenced by sitting in an Altoids tin or too close to a metal front panel, either. The pic I have attached is my toroid version of the famous Australian "Mystery Set" built in a hobby store Halloween decoration?. It works pretty well. I have a couple of different experimental toroid crystal sets built on plastic clipboards that work reasonably well (I've logged something like 9 states so far), some oatmeal boxes, some Morgan copies, I've used all kinds of detectors--foundry coke, razor blades, old tools, chunks of Ge, Si, (probably oxidized), galena, pyrite, a jillion other things, including LEDs (which we have strong enough signals to light up and I can drive a homemade horn loudspeaker made from a piezo element to audible volume) and some diode junctions old credit card chips, and various ICs like a 555. I think think someone DID actually make a receiver out of 555, but I'm just using a PN junction available at a couple of pins. Another FUN circuit is the loop antenna (I've made them on "acquired" milk crates and ~2-ft quilting loops. Those work great on a regular RX with inductive coupling, but if you put a diode/earphone? on it, you can easily hear loud locals.??
Might be fun to see if Rex wants to delve back into XTAL sets with QRPME.? I know he's done a lot of XTAL set work in the past.
-HRS
H. Russell Smith, N0QLT???
?????????????????????????????
On Saturday, April 15, 2023 at 01:52:49 PM CDT, John Putnum, AC9UV <johnfputnam@...> wrote:
Chuck,
I think that response was from me.? H* is a tap point shown in the Sea Sprite Schematic that is the tap point just after the LPF. I mentioned it because it is also marked on the PC board just after the LPF.? The Transformer in the SSEz build is to match the end fed wire, so if you hook a 50 ohm dummy load at the marked Antenna connector on the board you have a large mismatch and low SWR and the feedback into the circuit provides some funny results (attached photo).
As to using the supplied antenna or another antenna, I would put an antenna analyzer in series with the antenna and see what kind of SWR you get. If not very good, a tunner between the antenna and the analyzer and tune it up then you can take out the analyzer.? The Antenna and swr are important, when you have your rig, the swr is the gold to getting your signal out.
? ?---John AC9UV
On 04/15/2023 7:29 AM Chuck Carpenter <w5usj@...> wrote:
On Sun, Mar 26, 2023 at 02:22 PM, Daniel KK4MRN wrote:
Daniel, First, you got a good response to your request or folks to join the QRPmekits group.
I have comments about a couple of things in the message:
I learned how to tap off?point "H" and ground to use a 50ohm power meter and 50ohm dummy load to measure QRP power levels or use a different antenna.
I didn't attend the VideoAthon but I'm considering building the Sprite Kit. What is point H? Why not describe it as the junctions of (parts connected to point H).
And are there also other steps needed? What are the other options?
Or, I could just the end fed random wire antenna and 9:1 unun and counterpoise that I already am using, but I need to finish my home brew z-match.
What would the 1:9 RF transformer do that isn't already being done by the no-tune (1:8)** RF transformer? If you use a counterpoise with the 1:9 transformer, the antenna becomes an EFLW with much lower feed-point impedance. So maybe a 1:4 transformer would be better.
** A 1:8 turns ratio is 50:3200 Ohms impedance ratio.
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Re: Photo of my Sea Sprite+ in my ham shack
Chuck,
I think that response was from me.? H* is a tap point shown in the Sea Sprite Schematic that is the tap point just after the LPF. I mentioned it because it is also marked on the PC board just after the LPF.? The Transformer in the SSEz build is to match the end fed wire, so if you hook a 50 ohm dummy load at the marked Antenna connector on the board you have a large mismatch and low SWR and the feedback into the circuit provides some funny results (attached photo).
As to using the supplied antenna or another antenna, I would put an antenna analyzer in series with the antenna and see what kind of SWR you get. If not very good, a tunner between the antenna and the analyzer and tune it up then you can take out the analyzer.? The Antenna and swr are important, when you have your rig, the swr is the gold to getting your signal out.
? ?---John AC9UV
toggle quoted message
Show quoted text
On 04/15/2023 7:29 AM Chuck Carpenter <w5usj@...> wrote:
On Sun, Mar 26, 2023 at 02:22 PM, Daniel KK4MRN wrote:
Daniel, First, you got a good response to your request or folks to join the QRPmekits group.
I have comments about a couple of things in the message:
I learned how to tap off?point "H" and ground to use a 50ohm power meter and 50ohm dummy load to measure QRP power levels or use a different antenna.
I didn't attend the VideoAthon but I'm considering building the Sprite Kit. What is point H? Why not describe it as the junctions of (parts connected to point H).
And are there also other steps needed? What are the other options?
Or, I could just the end fed random wire antenna and 9:1 unun and counterpoise that I already am using, but I need to finish my home brew z-match.
What would the 1:9 RF transformer do that isn't already being done by the no-tune (1:8)** RF transformer? If you use a counterpoise with the 1:9 transformer, the antenna becomes an EFLW with much lower feed-point impedance. So maybe a 1:4 transformer would be better.
** A 1:8 turns ratio is 50:3200 Ohms impedance ratio.
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Re: Some BCI Filter Notes
Chuck,
There has got to be a chart somewhere telling me how many turns is the maximum per wire size on some of these various toroid sizes. The fact that you and Rex said to use 20 turns of number 24 ga wire on a? T37-2 toroid is probably telling me that #22 ga might not fit on it. Just saying, LOL.
Thank you for the very thourough into that I will keep in mind while doing these many toroid windings. My biggest issue so far is my big fat fingers, especially after spending weeks working on the RV to make it dry camping super friendly.
Cheers, Davey - KU9L
On Saturday, April 15, 2023 at 04:49:35 AM EDT, Chuck Carpenter <w5usj@...> wrote:
John,
The MRCC Link:? I did a search for Mini Ring Core Calculator.
WOW... Lots of hits.? Not sure which one to pick. There are two versions, 1.2 and 1.3.3 and they are from Germany.
Still using ver 1.2 as there was a language problem (for me) with 1.3.3 when it was first available so I've not upgraded.
I think it's been englishized now. Maybe someone on QRPtech is more up-to-date on a safe link?
Davey,
Use the largest size that will fit the number of turns on the core. The resistance of the wire goes up with the small gauges. That will reduce the "quality" of the circuit where used. Maybe not much but...
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Re: Photo of my Sea Sprite+ in my ham shack
On Sun, Mar 26, 2023 at 02:22 PM, Daniel KK4MRN wrote:
Daniel, First, you got a good response to your request or folks to join the QRPmekits group.
I have comments about a couple of things in the message:
I learned how to tap off?point "H" and ground to use a 50ohm power meter and 50ohm dummy load to measure QRP power levels or use a different antenna.
I didn't attend the VideoAthon but I'm considering building the Sprite Kit. What is point H? Why not describe it as the junctions of (parts connected to point H).
And are there also other steps needed? What are the other options?
Or, I could just the end fed random wire antenna and 9:1 unun and counterpoise that I already am using, but I need to finish my home brew z-match.
What would the 1:9 RF transformer do that isn't already being done by the no-tune (1:8)** RF transformer? If you use a counterpoise with the 1:9 transformer, the antenna becomes an EFLW with much lower feed-point impedance. So maybe a 1:4 transformer would be better.
** A 1:8 turns ratio is 50:3200 Ohms impedance ratio.
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Toroid Characteristic Values AL- uH-Turns
Wrote this many years ago as a memory help. If its more than you want to know, I'll stop being so loquacious... ........................................................................... In the process I found for iron powdered cores, T50-6 for example, that there are two values used for AL depending on the equations used for the calculations; 4 and 40**. Diz uses a value of 4 as does the Mini Ring Core Calculator and probably others. ARRL Handbook iron powder tables, sourced from Amidon data, use a value of 40. AL values of 4 work with this equation:? mH = (AL x N^2) / 1000,? AL = (1000 x mH) / N^2 AL values of 40 from Handbook tables work with this equation:? N = 100 (sqrt ( mH / AL)) Where: ??? AL = calculation constant for toroid material and mix ???????????????? mH = desired or calculated/measured inductance ????????????????N = numbered of turns desired or calculated However, with iron powdered toroids, the AL value calculated depends on the distribution of the turns. Example:? FT50-6
????????28 turns evenly distributed over about 330 degrees, 3.2 mH, AL = 4.08
????????17 turns evenly distributed over about 330 degrees, 1.265 mH, AL = 4.35
? Using 10 turns to evaluate AL simplifies the results; equation resolves to: AL = 10 x mH
????????10 turns closely spaced, .614 mH, AL = 6.14
????????10 turns evenly distributed over about 330 degrees, .441 mH, AL = 4.41
With the Handbook equation for number of turns:
For 3.2 mH on the T50-6, the turns would be:? N = 100 (sqrt(3.2 / 40));? sqrt(0.08) = 0.28 x 100 = 28 turns.
The Handbook equation for ferrite and number of turns:? N = 1000 (sqrt (uH / AL))
Use the tables for AL and the material for the core mix
** The handbook tables list the AL values for commonly used cores and mixes, both iron powder and ferrite.
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Re: Some BCI Filter Notes
John,
The MRCC Link:? I did a search for Mini Ring Core Calculator.
WOW... Lots of hits.? Not sure which one to pick. There are two versions, 1.2 and 1.3.3 and they are from Germany.
Still using ver 1.2 as there was a language problem (for me) with 1.3.3 when it was first available so I've not upgraded.
I think it's been englishized now. Maybe someone on QRPtech is more up-to-date on a safe link?
Davey,
Use the largest size that will fit the number of turns on the core. The resistance of the wire goes up with the small gauges. That will reduce the "quality" of the circuit where used. Maybe not much but...
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Re: Photo of my Sea Sprite+ in my ham shack
Hey John,
I see the photos now.? Very nice.? ?I think your power meter says 398 ?? As in 398 milliWatts?? Hard to tell.
And I see the harmonics showing in your TinySA spectrum analyzer.?
Going forward, I like to put my projects in strong cases.
Jameco aluminum enclosure for US$8.? However, not sure if this is the same size I show in my photo or not.? I originally got this case for my QCX that I have not finished.? So, plan on buying more of these enclosures.
Here, I put the Sea Sprite+ including its can in a case from Jameco.? However, I was only trying to see if it would fit.? I like my cases to be a little bigger than I need to give me room to work around.? I broke pots off the pcb of a MFJ Cub I built because I kept taking the board out of the case and putting it back in.? I kept trying to re-align the radio to get the best performance...? ?Or I wanted to show another ham its internals.? ?Anyways, and I had QRPme kits in the past where parts or modules got lost or pcb got damaged.? So, I like to put my stuff in metal enclosures now to protect them and so I will not lose parts like finals and crystals and band modules.? Plus, protect it from dust. I think the only radios you would not put in a metal enclosure are crystal radios and regens and AM radios where the bar antenna is in the box with no external antenna.
I will have to drill holes to put the off board connectors for power, antenna, phones, and key.? But to me, that is no big deal.? It is putting variable capacitors, LCD displays, pots, etc... into the case is when it gets hard.? But the sea sprite does not have those things - so no worries.? Yet, I probably - if i knew where to connect it - wire up a cheap frequency counter LCD display you can find on Amazon or ebay these days.? Then again, the radio is rock bound (crystal is 7110), so no point in a frequency counter?
I used a similar case from Jameco for my homebrew z-match for QRP radios.
Question, any recommendation for screwing the sea sprite+ pcb and can to the case?? Maybe drill a hole in the case?
73 Daniel KK4MRN
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Re: Some BCI Filter Notes
Chuck,
MRCC? do you have a link for that.? I like and use for torroid winding calculation. You can click on the torroid type and enter inductance or turns.?
---John AC9UV
? ?73
On 04/14/2023 5:05 AM Chuck Carpenter <w5usj@...> wrote:
Davey,
Looks like you have the toroids figured out.? T37-6 would be yellow.
A utility I like for inductors is Mini Ring Core Calculator. Find it on the web.
I assembled the N4ELS filter, aka the QRPme HPF filter kit;
a basic filter using common part values. Toroids are T37-2.
The nanoVNA was used to get sweeps of toroids at 1.8uh and 1.5uH.
Results were pretty much the same with 1.5 having better input impedance.
This is a broad cast band filter. It won't do anything to help SWI short wave interference.
A second higher frequency LPF would help with that problem. As is, between 500kHz and 1.6MHz,
the attenuation ranges from about-70dB to -40dB
Note that the combination looks a lot like a BPF...8^) That was attempted but...
If the SWI is from a single station, a series-tuned notch filter would help. MRCC has a feature
that helps determine L/C values using F of station.
To cover lower bands, the components get more complicated and use values that are
not standard.
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David Knapp
