Re: Lifetime resistor supply
It's the cheap no-name brands that seem to have the rust problem, I suspect better quality ones might be OK.
?
My aversion to this stuff stems from back when I used to manufacture stuff that had to use top quality first tier components as part of the contract.
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With the quantities of resistors I have here, my kids grandkids will probably have a lifetime supply (I still have some 5000 quantity reels left over from that time) ?
--
Terry VK5TM
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output levels desired
1.? 50uV? (-73dBm)
???? 1uV? (-107dBm)
Voltage divider to get to the 50uV before starting attenuation.
Sorry for the earlier confusion.? Typos galore.
Obviously requiring a severe amount of isolation away from the
original generator, whatever it is.
Look at what Jim, K8IQY, did for his.
<>
And that was for just a simple crystal oscillator.
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Thank You Chuck !? ?I'll be watching.? I want to build the DC RX Manhattan style. I just ordered a few NE602 and NE612 from AliExpress.? I hope they are genuine. Jim WB4ILP?
On Sun, Mar 23, 2025, 4:27 PM chuck adams via <chuck.adams.phd= [email protected]> wrote: Thread just started and already have one correct.? Schematic and BOM to be
found or reconstructed later today.? Just finished a Manhattan board for
the other project in progress.? Stay tuned.
On 3/23/25 10:56, Jim WB4ILP via wrote:
> Hi Chuck,
> I haven't been following this thread.? Where do I find the schematic
> and BOM for the DC RX?
> Thanks !
> Jim WB4ILP
>
> On Sun, Mar 23, 2025, 10:52 AM chuck adams via
> <> <chuck.adams.phd=[email protected]> wrote:
>
>? ? ?Forgot. Here is board layout for the DC receiver.? Gerbers at 11.
>
>
>
>
>
>
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When I buy resistors, I usually buy 100 of a value at a time.? I buy 1/8, 1/4, 1, 2, 3 ,and 5 watt values.? (Buying in big quantities reduces prices.)? Because of the quantity, small pouches are out of the question for me.? So I put each value of each wattage in separate sandwich sized freezer bags.? Freezer bags are heavier duty than sandwich bags.? I then put each wattage bagged resistors in same sized boxes? (8x12x5)? (All 1 watt resistors go in the 1 watt box.)? I always put in a paper label in each bag showing it's resistance.? This works out very well for me.? When working on restoring boat anchor rigs I always use a larger replacement wattage then original to keep physical sizes approximately the same.
Lee, w0vt
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I'll add the cap.? Don't remember at the time it being an issue.
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On 3/23/25 08:55, Mike Dinolfo via groups.io wrote: Chuck:
This looks like a nice, clean PC board layout, and thanks for sharing
your work with us on this group!
Just a comment- looking at the layout, are you intentionally letting pin
1 of the NE602 "float"?? Maybe it would be preferable to bypass it to
ground (for RF, not DC); perhaps with something like a 0.1 ufd cap?
Mike N4MWP
On 3/23/25 10:52, chuck adams via groups.io wrote:
Forgot. Here is board layout for the DC receiver.? Gerbers at 11.
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Thread just started and already have one correct.? Schematic and BOM to be
found or reconstructed later today.? Just finished a Manhattan board for
the other project in progress.? Stay tuned.
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On 3/23/25 10:56, Jim WB4ILP via groups.io wrote: Hi Chuck,
I haven't been following this thread.? Where do I find the schematic and BOM for the DC RX?
Thanks !
Jim WB4ILP
On Sun, Mar 23, 2025, 10:52 AM chuck adams via groups.io <> <chuck.adams.phd@...> wrote:
Forgot. Here is board layout for the DC receiver.? Gerbers at 11.
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Hi Chuck, I haven't been following this thread.? Where do I find the schematic and BOM for the DC RX? Thanks ! Jim WB4ILP?
On Sun, Mar 23, 2025, 10:52 AM chuck adams via <chuck.adams.phd= [email protected]> wrote: Forgot.? Here is board layout for the DC receiver.? Gerbers at 11.
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On Sun, Mar 23, 2025 at 04:20 PM, chuck adams wrote:
? Just attenuate to 0.5uV and let the receiver remove all the harmonics.
?
The title says S9 (50uV) generator. What are the 0.5uV for?
?
--
73, Robert
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Before 40 people jump in to correct me on absolute levels from this square wave output, I was being somewhat tongue in cheek in my reply. Even if the absolute fundamental output of this generator is even 0 dBm, there is a lot of attenuation needed to get the signal down to -113 dBm. (It's easier to think in dB units than volts.)
73,
Steve AA7U
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On 3/23/2025 8:38 AM, Steve Ratzlaff wrote: 4.2 volts across 50 ohms is +25 dBm. 0.5 uV across 50 ohms is -113 dBm. That's an awful lot of attenuation you're going to need (25 + 113)--I doubt your extensive shielding needed between input and output will be sufficient.
Steve AA7U
On 3/23/2025 8:20 AM, chuck adams via groups.io wrote:
I did the math.? Fundamental amplitude for a square wave is 4*A/pi, where A is the square
wave amplitude.? For A=3.3V, then fundamental is 4*3.3/pi ~= 4.2V.? Just attenuate to
0.5uV and let the receiver remove all the harmonics.? I think this will work and we
won't have to switch between filters in the generator.? Someone do the experiment
and report back.
I'm 532/937 on ProjectEuler.net, so I think my math is right.
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I do! ?Still available? ?If so, I¡¯ll take it.
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On Mar 23, 2025, at 8:32?AM, bill K7WXW via groups.io <K7WXW@...> wrote:
I have an extra copy of EMRFD, brand new with the CD still in the unopened back pocket, because someone gifted me an old copy roughly a week after I found this one. I paid $60 plus shipping for it, which is apparently a bargain (I think the original ARRL price was $45 plus shipping). Anyone need a copy?
?
Cheers,
Bill K7WXW
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Chuck:
This looks like a nice, clean PC board layout, and thanks for sharing
your work with us on this group!
Just a comment- looking at the layout, are you intentionally letting pin
1 of the NE602 "float"?? Maybe it would be preferable to bypass it to
ground (for RF, not DC); perhaps with something like a 0.1 ufd cap?
Mike N4MWP
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On 3/23/25 10:52, chuck adams via groups.io wrote: Forgot. Here is board layout for the DC receiver.? Gerbers at 11.
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I believe you can reduce the output level somewhat in the software to help with the attenuation.?
73 Don ve3ids?
On Sun., Mar. 23, 2025, 11:38 a.m. Steve Ratzlaff via , <ratzlaffsteve= [email protected]> wrote: 4.2 volts across 50 ohms is +25 dBm. 0.5 uV across 50 ohms is -113 dBm.
That's an awful lot of attenuation you're going to need (25 + 113)--I
doubt your extensive shielding needed between input and output will be
sufficient.
Steve AA7U
On 3/23/2025 8:20 AM, chuck adams via wrote:
> I did the math.? Fundamental amplitude for a square wave is 4*A/pi,
> where A is the square
> wave amplitude.? For A=3.3V, then fundamental is 4*3.3/pi ~= 4.2V.?
> Just attenuate to
> 0.5uV and let the receiver remove all the harmonics.? I think this
> will work and we
> won't have to switch between filters in the generator.? Someone do the
> experiment
> and report back.
>
> I'm 532/937 on ProjectEuler.net, so I think my math is right.
>
>
>
>
>
|
4.2 volts across 50 ohms is +25 dBm. 0.5 uV across 50 ohms is -113 dBm. That's an awful lot of attenuation you're going to need (25 + 113)--I doubt your extensive shielding needed between input and output will be sufficient.
Steve AA7U
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Show quoted text
On 3/23/2025 8:20 AM, chuck adams via groups.io wrote: I did the math.? Fundamental amplitude for a square wave is 4*A/pi, where A is the square
wave amplitude.? For A=3.3V, then fundamental is 4*3.3/pi ~= 4.2V.? Just attenuate to
0.5uV and let the receiver remove all the harmonics.? I think this will work and we
won't have to switch between filters in the generator.? Someone do the experiment
and report back.
I'm 532/937 on ProjectEuler.net, so I think my math is right.
|
I have an extra copy of EMRFD, brand new with the CD still in the unopened back pocket, because someone gifted me an old copy roughly a week after I found this one. I paid $60 plus shipping for it, which is apparently a bargain (I think the original ARRL price was $45 plus shipping). Anyone need a copy?
?
Cheers,
Bill K7WXW
|
I did the math.? Fundamental amplitude for a square wave is 4*A/pi, where A is the square
wave amplitude.? For A=3.3V, then fundamental is 4*3.3/pi ~= 4.2V.? Just attenuate to
0.5uV and let the receiver remove all the harmonics.? I think this will work and we
won't have to switch between filters in the generator.? Someone do the experiment
and report back.
I'm 532/937 on ProjectEuler.net, so I think my math is right.
|
Forgot.? Here is board layout for the DC receiver.? Gerbers at 11.
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1.? I decided I would go ahead and keep the 3120 pcs resistor kit.? We get about 10cm of
??? rain per year and usually in one or two storms during summer monsoon season.
??? I'd quote a line from 'Oklahoma Crude' with Faye Dunaway and George C Scott,
??? but that would not be appropriate.? :-)? Measurements in circuit show the
??? critters stand up to heat and don't separate leads from internals upon
??? soldering.
2.? I went searching high and wide.? Can't find the QRP crystals for an S9 Signal
??? Generator like the old NorCal QRP Club had.
So here is an idea that I'll share with you.? I bought several of the following
from Mike at KitsAndParts.com.? It's his uni-VFO about the size of a US Quarter.
My start at hot plate soldering.? Got the paste and ready to go, but not this
week.
<>
<>
Critter generates 3.3V square wave, but using appropriate bandpass filter
(or not), get signal chain to output 0.5uV at QRP freq or any other.
Use an switchable attenuator in/out for getting 0.1uV to measure MDS
of a receiver.? Or an external attenuator like attached.? I got one last
week for this project.
Put S9 generator in PCB enclosure.? See K8IQY.com and his 20m signal
generator in beautiful enclosure.
I place here for you consideration.? I'll put the Gerber files for the
old DC receiver in the files section in .zip format later today. Remind
me if I slip up again.
I have the serial cable already and know how to use putty as I use it to
communicate with my MC6809 SBC used for regenerating an incremental
compiler for BASIC that I and three students wrote in late 1970s.
Wrote 3300+ lines in assembly.
Maybe some one has already been there and done that.? Project idea is
open source.? If you find a way to make money for this, have at it.
I don't think there is a handful of guys and girls that's need it.? IMHO.
FYI
chuck, aa7fo, lab rat gone mad
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?No problem, Michael,
Be sure to read K6WHP reply about two posts back in this thread; it is very comprehensive and will lead you to info that will help you decide which/where to buy yours. The nanovnausers IO group is indispensable.
I personally have a Nanovna-H4 and love it. Dislord firmware.
¡ªTim NC0Q
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Re: Lifetime resistor supply
I always wondered why my resistor end pieces were copper coated steel when I found I could pick up the pieces with a magnet¡¡. Must save a ton of money over the years of production. ?Copper coated steel is used in the antenna wire I buy from The Antenna Man and many wire antenna manufacturing companies use it too. ?I have never seen any corrosion even when portions of the wire were exposed to Michigan weather. Maybe a better copper coating??? ?So I doubt any of the POTA/SOTA projects would get enough water and air exposure to ¡°rust¡± to otherwise deteriorate. ?
This is a fun observation but wonder how much effect it really has on our radio builds. ? Keep writing. I am learning. ?But will still use up my resistor kits that magnets can pick up (if the Good Lord gives me another 20 years¡.. I am 80 now) until they are gone. Then may be using only SMD parts without leads. ?They are fun too. ?I don¡¯t shake yet but can¡¯t see or hear well so my wife confines me to the basement shack (until her iPhone or iPad has a problem. Then I am a hero).?
Just thought of the few things written above and with the world mess as it is everyone needs a laugh this morning. ?Hope it worked. ?Silky antenna wire is the berries in my book.
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On Mar 23, 2025, at 1:02?AM, Terry VK5TM <vk5tm@...> wrote:
? My experience with coated steel is that they rust and the problem with that is it can cause the leads to rust through/break over time - it gets worse if you build something for portable use and use that out in damp/wet weather, regardless of whether you are under cover.
?
As for brands, that I can't say off the top of my head as I normally buy a minimum 1000 per value from a wholesaler that supplies to industry , the packaging doesn't have any manufacturer branding on the last lot I bought.
?
For smaller quantities you'll be looking at the likes of Digikey, Mouser etc but their resistor kits aren't particularly cheap.
?
?
?
On Sun, Mar 23, 2025 at 01:59 PM, chuck adams wrote:
Yes, they are the coated steel leads.? Didn't know that would be or was a problem.
I checked and Amazon does have free return policy on them.
Is there a particular brand that you found that guarantees the plated copper
leads?
?
--
Terry VK5TM
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Tim, Thanks for sharing that info. Personally, I didn't know that the NanoVNA was capable of making such measurements (at least not accurately). Maybe it's time for me to buy one of those clever little gadgets. Careful measurements with "oscillators, frequency counters" will give accurate results, but those methods are tedious. If the NanoVNA can provide accurate results easily, and is inexpensive, then it sounds like all the other methods have been made obsolete.?
Now I'm off to do some shopping :)? Thanks again. 73 Mike M.? KU4QO
On Fri, Mar 21, 2025 at 4:07?PM Tim Tyler II via <timtylerii= [email protected]> wrote: 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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Kaufman, Matt - N3AR
Mike Dinolfo
Don VE3IDS
bill K7WXW
David Wilcox K8WPE