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I don't know if anyone else has run into this.? I do quite a bit of smd soldering or try to.? I have bought many many cross tweezers from several sources that claim they are stainless steel.? The problem is that they are either not stainless steel or are a very low grade as they are magnetic.? Tonight I was trying to set a couple 1206 rf chokes and my stainless steel magnets kept grabbing the part and not wanting to let go!? How does one know if the tweezers are actually non magnetic?

Thank you.

Jim Pruitt
WA7DUY

If you don't mine, send away.

ciao dude,

chuck

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Tayda Electronics also carries capacitors in that yellow blob shape; I've bought a bunch of them off and on. My DE-5000 LCR meter has a Dissipation Factor function that works in capacitance mode that I've found to be useful for judging these small values of caps used in RF circuits (and displays along with the capacitance value--you don't need to do anything to get the Dissipation readout). High quality good caps with very low dissipation will have a D of 0.000 even at the default 1 kHz test frequency (where I normally test caps but use 100 kHz for all RF inductors). Most of these Chinese caps will show a higher dissipation, sometimes up to 0.006 I've seen, with many in the .002--.003 range. If you need to use a good cap such as in a frequency sensitive circuit, I'd stay away from the caps that don't read 0.000 Dissipation factor.

73,

Steve AA7U

For the all transistor transceiver group.

You will need to match crystals.? Here is one option of many.

Go to W7ZOI.net and go to the technical stuff button top right.
At the bottom of the new page is a section labeled filter design
and crystal things.? Top of the list is "9 MHz Filters with
Inexpensive Crystals".? There is a Colpitts Oscillator in Fig 3.
First photo below is my build using Manhattan Construction.? I'm
a bit rusty and some things I forgot.? 1.? I hate Rustoleum with
a passion.? It is a very very good paint.? That is the problem.
Used clear matte on the base board.? It just won't melt with the
soldering iron.? I'm going to drive miles to find a can of Krylon
for any other boards in the future.? 2.? Use an IC socket cut to
three pins for interchanging parts.? The 2.54 headers work, but
sometimes flaky.? 3.? Use the 2.54mm vector board to get pins
to 2.54mm spacing, like some preformed legs from manufacturers,
for ease of changing in and out.

I changed the 47 ohm resistor to 10K to drop the voltage on the
collectors of the transistors to around 8V.? Second photo shows
4MHz crystal output with the circuit.? That is the frequency
the counter showed for a whole hour.? Not a Hz shift at all.
Reasons.? Room temp never changed.? We used crystals on HP projects
for thermometers back in the day.? With the lower voltages there
is less heating of the crystal, thus no drift.

Note the sockets for the transistors.? Tried 2N2222s from the 840
pack (third figure) and the 2N3904.? The 2N2222 does not work.
The 2N3904 does.? I tried a stray 2N4401 in a small plastic
container of random parts and it works.? This for the 4.000MHz
crystal.? No joy for 9.0000MHz crystals.? This due to the 470pF
caps being too large.? See specs for other crystal checkers.

Here are the h_fe figures for the three transistors.? This done with
the Chinese Critter Checker.
2N2222? h_fe = 288
2N3904? h_fe = 359
2N4401? h_fe = 439
You can see why I prefer the 2N4401, even though a number of sites
show them as interchanging parts.? There are plus and miuses in life.

This checker to be used later (with mods).? If you don't have a freq counter,
possibly an SDR.? General coverage receiver with SSB/CW capability.
Use fixed dial setting and match tones of the crystals.? Closer than
a random selection.

I recommend, for all new Manhattan builders, to try this out.? It will get
you started.? IMHO.


FYI and thank you for your time,

chuck

OH.? For the 840 pack of transistors.? You can throw the chart out.? It is
an Easter egg hunt for the right parts.? Some one has a sense of humor at
the assembly line.

Jim,

I have to go back into the bat cave to find what I need.? It's not on my current
drives and I have an old computer in a cabinet to dig out.? Then I have to
go through the DVD collection to find the old stuff.

This will take time and may take a day or two.

There may be a better alternative.?? Those interested, form a search party.
Go to archive.org and the wayback machine and search for k7qo.net and
k7qo.com.? Some the snapshots do not grab all the material.

We did the DC project on qrp-tech.io and the posting there may help.
Surely, someone on this group has the documents and you may fell
free to put them in the files section for those interested.

Another option.? Search the internet for DC receivers and there are a number
of candidates for the project and I recommend modifying to allow the use
of the new digital VFOs.? QRPGuys,? KitsAndParts and QRP-Labs to start a
list of DDS VFOs available for a multitude of projects.? Let lose the hounds.

FYI


BTW.? Jim is in charge.....? :-)

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.

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

I'll add the cap.? Don't remember at the time it being an issue.