Re: Lifetime resistor supply
Ask and you shall receive.? Amazon (let's make Jeff richer site) and search for
"1/4W carbon film resistor kit" and you get a large selection that I have done
gone through.? I just picked this.
FYI
gold precision band for 5%
chuck, aa7fo
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On 3/22/25 09:14, k6whp via groups.io wrote: Thank you. These sound ideal as -- I am sure you know -- the blue colored ones are the devil to distinguish green, red, blue, etc.
If you care to share a link, I'm sure others would appreciate same.
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
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Re: Manhattan Construction Classes
I'm about to post my second video in an hour.? In it there is a
cheap Chinese component tester.? Find them on amazon and all your
favorite critter suppliers online.? Attached photo.? I have one
with the plastic case to prevent a disaster on a workbench with
a copious supply of clipped component leads.? :-)
Went over to the other desk, took the critter and I have a pill
bottle with a long strip of diodes and took four of them and
measured them.? Surprise.? The voltage drop was 253mV.? Looked
with jewelers loupe and the band is green.? They are Ge diodes.
I thought they were 1N4148s.? Need to label the bottle.
The voltage drop measurements show 3 decimal places and I can
see a +-1 mV change.? Not sure that is enough, but it may be.
I'll do a finer measurement in a video, but in the meantime
maybe someone else can do a finer report for the audience.
It'd starting point for testing.? I'd use a solderless
protoboard and a battery, a current limiting resistor
and power up diodes and measure the voltage drop at a low
current level, since that is where they are going to be
used in a ring diode mixer.
chuck, aa7fo
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On 3/22/25 08:23, Alan N8WQ via groups.io wrote: Hi Chuck,
Can I make a recommendation for your Manhattan Construction Classes?
Can you make a video about matching diodes?
Thanks!
Alan, N8WQ
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Re: Lifetime resistor supply
Thank you. These sound ideal as -- I am sure you know -- the blue colored ones are the devil to distinguish green, red, blue, etc.
?
If you care to share a link, I'm sure others would appreciate same.
?
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
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Re: Lifetime resistor supply
William,
Four strips, so they are marked for precision range.
Body is tan, typical for carbon film resistors.
FYI
chuck, aa7fo
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On 3/22/25 08:11, k6whp via groups.io wrote: Are they four stripe or five stripe coded and are the resistor bodies blue or tan?
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
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Manhattan Construction Classes
Hi Chuck,
Can I make a recommendation for your Manhattan Construction Classes?
Can you make a video about matching diodes?
Thanks!
Alan, N8WQ
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Re: Lifetime resistor supply
Are they four stripe or five stripe coded and are the resistor bodies blue or tan??
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
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Crystal Experiment for Beginners and Experts Alike
I'm in the middle of a big project, but I ran across a need for the following
and I'm on a side excursion in the lab for a few hours and I thought some in
the group might be interested in trying this.? That is, if you are bored.
In EMRFD by Wes Hayward, W7ZOI, Chapter 1, Page 1.11, Figure 1.15 is a
schematic for a simple Colpitts crystal oscillator.? And if you don't have
a copy of EMRFD, shame on you.? :-)? BTW.? The book came with a CD with his
RF Design book, that I scanned in and Wes used for the second printing.
OK, I got lost.? Looks like book is no longer in print that I can tell.
Copy on amazon for $92!!!? I don't think anyone will buy it at that price.? IMHO.
<>
We all could get rich!
Project:? Build the critter.? Use a socket for the crystal, but also use a socket
for the transistor.? Model the circuit using LTSpice and/or ngspice and use
K8IQY.com for the crystal parameters, if you don't already have some you measured.
Experiment with output levels for different frequencies and different transistors.
I'm building one as we speak to add to the set of tools to test crystals and also
to test transistors from China.? Some one mentioned, and I apologize for not looking
up the name and call, measuring the noise figure.? Care to give the group a lesson?
It would be appreciated.? I'm going to go through my pile of different sets to
eliminate any future problems.
Sharing,
chuck, aa7fo
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Jim, you may want to check out this website: ?
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Best,
AK6GX
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On Fri, Mar 21, 2025 at 08:18 PM, Daniel KK4MRN wrote:
Do you have to install some firmware on your nanovna for it to work?? And that you have to make sure it is certain nanovna?? not all will work.?
?
Firmware is something called Dislord?
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I have NanoVNA-H but not the H4.??? Will the NanoVNA-H work which has a 2.8" screen?
This is what it is.? Note, I got it much cheaper in the past - but inflation these days...
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Probably best it have its own topic for using NanoVNA for matching crystals.
?
Daniel,
?
A preamble: this group is loaded with wizards and these guys (and gals) know a lot about stuff. That I recommend other sources by no means discredits the folks here. It's just that it might be a little off topic. THIS IS NOT AN ADMONITION! Just pointing out other resources.?
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(1) You do NOT have to install firmware on your NanoVNA to make it work. Depending on when you purchased yours, it will have firmware ("FW") it was initially "burned" with.
(2) The FW will be vary old and, while that is not at all bad, there are some new features that would make upgrading desirable.
(3) By the same token, you might want to upgrade your NanoVNA as well. The H with the smaller screen leaves a lot to be desired.
(4) Similarly, the later/latest FW upgrades will function on an H4 or other VNAs with a 4" screen.
(5) The H4 models' price have declined violently; they sell on Amazon for much less than when I purchased mine circa 2020.
(6) Then: over $100 Now: around $80 on Amazon. About $5-10 less on eBay if you want to wait a month for Chinese shipping.
(7) There are many YouTube videos with NanoVNA "intros". They are cursory and most don't handle the topic comprehensively.
(8) Recommend the following series as being more comprehensive. It starts with this one:
?
?????
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(9) ..and includes with this one which is a comprehensive tour of the menu and, perforce, the machine:
?
? ? ?
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(10) Recommend viewing all at your leisure. These videos will fill a lot of the holes the other "intros" will leave you with.
(11) Similarly, there is a group -- nanovnausers -- that is loaded with folks and info on these little beasts.?
(12) Asking and searching threads reveal incredibly useful tidbits. Also cruise their "Messages" and their "Wiki sections as well.
(13) The Wiki contains overviews of models, FW, etc. Here is the H4 "Wiki"
?
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..note the directions on how to upgrade FW.
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I was pressed back into using (and therefore re-learning) how to use my H4 recently. Without the resources above, I never would have realized what a powerful little gadget these are.
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Good luck.
?
--
William, k6whp
--------------------
"Cheer up, things could get worse. So I cheered up and things got worse."
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Tim,
Do you have to install some firmware on your nanovna for it to work?? And that you have to make sure it is certain nanovna?? not all will work.?
?
Firmware is something called Dislord?
?
I have NanoVNA-H but not the H4.??? Will the NanoVNA-H work which has a 2.8" screen?
This is what it is.? Note, I got it much cheaper in the past - but inflation these days...
?
Probably best it have its own topic for using NanoVNA for matching crystals.
?
Anyways, I went searching, I found this link:
?
Look at the text:
Due to the discontinuation of NXP SA612A, we started to produce compatible chip ZeeTK NE602A, but due to the different chip manufacturing process, there is a slight difference between the two in the use of harmonics, new compatible ZeeTK NE602A NanoVNA-H rev3.7 and NanoVNA-H4 rev4.4 version hardware schematic.
?
Daniel KK4MRN
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In this photo, I have not taken the time to calibrate/zero-out my test setup, so the displayed data is far from accurate. I¡¯m only trying to show how I test crystals. The other pic is my test jig. I use a normal 1/8W 50 ohm resistor for a calibration standard load, a jumper for the short, and room air for the open. Seems to work FB. I believe I paid around $75 dollars for my NanoVNA-H4.
¡ªTim NC0Q
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Received today from amazon from an order made yesterday:? 3120 pcs 1/4W 5% Carbon Film
Resistor assortment kit.? Price:? $17.99.? Trusty HP-35 calculator says $0.0058 per critter.
Measured random sample with the Velleman DVM1100 meter and they all fall within 3% so far.
I checked the meter against NIST standards and it is within 0.6%.
Of course, I don't recommend any one to order that large a stock. Not unless you are
producing a kit that uses them all.
Oh, each strip is labeled so you don't have to read color codes or get out the
DVM.
Got the thin leads and we are going to be stuck with them forever.? Price of copper
is too high with the demand for EV motors so high.
FYI
chuck
P.S.? New youtube channel @aa7fo? for start of the ADC project. Hoping for two a day.
Report coming tonight on the audio amplifier section build and test.? Like and subscribe.
Begging like a vloggers.
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ADC 40 to 20 conversion progress
I have a partial ADC 20 conversion receiver section built but I'm not sure the 9 MHz IF filter is working properly--I don't have any 9 MHz crystals that have much Q, for one concern. I decided to built the ADC 40 receiver section so I could compare voltages and waveforms. I finished it today and it's working properly and sensitivity matches the original (stated in the article as 0.5 uV/-113 dBm). I matched up some 4 MHz crystals for the IF filter--the one I characterized had Q 140k. The VFO is set to around 7030 kHz (fix-tuned). The VFO buffer Q7 is interesting--it "sort of" squares up the sinewave from the VFO--that wasn't mentioned in the article. At 13.0 V supply (shown on the schematic as 13 V), no-signal receive current is 60.5 mA. (I don't have Q6,9,10 installed since I'm just interested in the receiver for now.) I didn't have a 12 uH choke (L3) so wound a T37-2 with 55 turns of #32. The 30 pF trim cap C14 wasn't enough to peak resonance so I added a fixed cap. I used a T50-7 (white) toroid for the VFO inductor L4. I'm using J310 jfets for both sets; 2N4401 bipolars from Mouser.
73,
Steve AA7U
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Watching this conversation with interest. I am surprised nobody has mentioned using a nanoVNA to characterize crystals. I did this with a bag of 10MHz crystals, sorting to spreadsheet, and was able to build a dang good IF filter. I still have a bag of 12MHz crystals to go through. My nanoVNA has a ¡°crystal test¡° function, and spits out all the fun numbers like series resonant frequency, parallel resonant frequency, Rs, Cs, etc¡
I am no engineer, and am poorly educated compared to most on this list, so I assume there must be a compelling reason to use oscillators, frequency counters, and trigonometry etc., if only for the fun of it.
I personally doubt that the nanoVNA generates data that would even come close something provided by laboratory grade instrumentation, but it seems to be close enough for amateur work.
Apologies for any confusing typos, homonyms, rogue commas, that I may have missed¡ I dictated this email to my phone in a loud automotive shop environment during a break.
¡ªTim NC0Q
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Thanks Steve.
I had another thought on this subject last night and I cobbled together a quick test. Stable frequency generators and high resolution counters might not be on everyone's bench. For fun, I wired up one of my Si5351 VFOs (a KitsAndParts Uni-VFO) and configured it to cover the range of frequencies of the 8MHz crystals I was testing. In "debug mode", the Uni-VFO outputs the relative frequency on a computer terminal. After the VFO, I put a resistive attenuator (simple 5k trim pot and 51 ohm resistor), then a simple low-pass filter at 10MHz. I turned it down to -20dbm output. I used that to feed Jim's (K8IQY) crystal test fixture that has two transformers to put the crystal in a lower impedance environment. The VFO has a 1Hz resolution, and is very stable after a few minutes of warm up.?
I measured a couple of the original test crystals again using this setup. The numbers were all within a few percent.?
So, it seems that you could use any of the many Si5351 VFOs out there, assuming they can be set for a 1Hz resolution, as a frequency source for this test fixture. It eliminates the need for an expensive RF generator and frequency counter. The only thing that is a little exotic in my setup is the RF voltmeter. I think you could easily put together a two-diode RF probe and just watch the DC voltage on a meter to find the peak and -3db points. Even better, wouldn't it be cool to automate the process?
73 Mike M.? KU4QO
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Re: 2N2/40 Transceiver Project
You're going to really enjoy the 2N2/40 Alan. I built mine from the kit, and used it as my only rig for the first few months after building it. My entire station was the 2N2/40, a little straight key, a set of earbuds, and a loaded vertical out on the balcony of my apartment. The rig was on 24/7. Whenever I wanted to operate, I sat down, slipped the earbuds in, and twisted the tuning knob. I had some great conversations, and got a really good feel for how the band changed during the day and night.
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I'll be watching this space and following your blog for updates.
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Dave
AA7EE
PS - thanks for leaving a few of those audio transformers for me at Mouser :-)
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Steve,
I want to get a similar tool. Is there markings on the die that show the size and are they in mm or AWG? I ntice some dies have AWG markings and some in millimeter.
73 Mike N2MS
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On 03/20/2025 4:40 PM EDT hwstar <steve@...> wrote:
I use these JST XH connectors in my projects. You need the proper crimping tool to do it right. The choice of crimping tool and the correct position for your wire gauge is vital.
A lot of the Chinese crimping tools do a poor job of crimping these connectors, I had to buy another tool after the first one with blue colored handle grips made very unreliable crimps. The second tool I purchased YEFYM model SN-2549S (red and blue with a silver colored crimp die) has been doing a great job.
I attached a picture of the second tool.
Steve
WA6ZFT
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Re: Multi-function test jig idea for homebrew radios.
This might be outside the scope of what you're looking for, but I found this video interesting, with good explanations of how the circuit works. This might be a fun "quick" project for a tool to get a good look at transistor DC characteristics. Plus, it is fairly?simple. Your test jig looks great! 73 Mike M.? KU4QO
Here are the updated schematics and board layout pictures for the multifunction tester.
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1. The diode tester has been completely revamped. It now has its own adjustable current source, and a way to set the diode current by using a switch to short the test current to ground.
2. The comment to add a differential diode test feature has been incorporated.
3. Added 3pF trimmer caps to adjust coupling in the Q/SRF tester
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Pictures of the layout and the schematic attached.
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Highly recommend the ¡°engineer¡± crimping tools like
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they are not cheap, and you will want to buy all 3.
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?You also need to individually crimp the wire and insulation prongs, but they are the first set of crimpers that I had success with.?
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73
Mark
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I have to fiddle with mine a bit too.?
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These tools won't be a perfect match to the contact and will not be as good as the tool you buy from the connector manufacturer. (For several hundred dollars typically) The rear crimps on the contact sometimes needs to be pressed a little towards each other to fit in the die, and I have to bias the contact slightly towards the front. However, I can insert the contact from the back of the crimp die (At least in my crimp tool).
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Steve
WA6ZFT
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k6whp
Alan N8WQ
hwstar