[HBQRP] Elmer 101 Part 2

Mon Nov 21 12:58:19 EST 2005

And before I forget.................concerning the rf probe. If you go to
N5FC's website and look at how the probe is wrapped in the copper foil, I
have on hand 36 yards of this stuff. Yeah 36 YARDS !!!!  I had my wife pick
it up at Hobby Lobby and she said that was the smallest quantity they had.
$5.99 was the cost. It's 1/4 inch wide and is called "stained glass foil".
It has an adhesive on one side covered with a paper backing which you just
peel off and stick to whatever. If you need some, let me know how much and I
can mail it you. If you're  in no hurry, I'll bring some to the next meeting
Jan 14th and you can get what you need then.

Hmmmmm, might be worth a try in making circuit board traces but don't know
how well the adhesive would hold after applying solder. Just an afterthought
here !

Steve/WBØQQT

----- Original Message -----
From: "Darrel Swenson" <dswenson at wearne.net>
To: "HBQRP List" <hbqrp at mailman.qth.net>
Sent: Sunday, November 20, 2005 11:58 PM
Subject: [HBQRP] Elmer 101 Part 2

> Hi Guys...
>
> After a quick survey, I'm not sure where everyone is...  I know of 4
people
> who are building along, 2 who are not, and ???  If you are building along
> let me know (and let me know where you are so we don't get too far ahead
of
> anyone.)
>
> Now for the VFO.  Remember the Elmer 101 material was written for the
SW40+,
> so a few of the parts are different for the SW30+ and SW20+...  The
> component name (C4, etc) should stay the same for all the bands, but the
> value may (or may not) change with the different bands.  I've listed the
> changes below:
>
> part     value
>          SW40+    SW30+     SW20+
> c2       47 pF
> c3       10 pF
> c4     2700 pF   3300 pF   1200 pF
> c5     2700 pF   3300 pF   1200 pF
> c6     3300 pF
> c8       82 pF    120 pF     27 pF
> c9       10 pF
> c10     270 pF
> c103    .01 mF
> c105    .01 mF
> D1      MV1662
> D2      1N4148
> L1     wind this
> Q2      2N4401
> R15     47K ohms
> R16     22K ohms
> R17    2.2K ohms (follow installation instructions on diagram instead of
> silkscreen)
> R18      1M ohms
>
> Follow the directions on page 3 and page 12 of the manual for winding L1
> (and the other toroids.)
> For the SW40+ it's 25 turns on the larger yellow .50 inch diameter core.
> ~18 inches of wire.
> For the SW30+ it's 29 turns on the larger yellow .50 inch diameter core.
> ~20 inches of wire.
> For the SW20+ it's 23 turns on one of the yellow .37 inch diameter cores.
> ~14 inches of wire.
>
> I've had a couple of questions about wire size and length.  IF I
understand
> toroid theory right, I think you can use the same number of TURNS of about
> any wire size from about 20 to 30 gauge and get the SAME inductance on the
> same core.
>
> The question is many turns of a wire gauge will fit on a size toroid, and
> how long of a chunk to start with for a wire size and toroid size.  The
> SW30+ directions say 18" of 24 gauge wire.  (I think this may be a typo
left
> over from the SW40+ original manual.)  The 18" of the wire supplied with
my
> kit will only get 27 or 28 turns.  (At least one other SW30+ builder had
the
> same problem.)  Diz's toroid calculator says about 20" for 29 turns on a
.50
> diameter core.  I used 20" and it worked out fine.
>
> A good source for toroid information is:
> http://partsandkits.com/
> http://partsandkits.com/xtoroids.html
> http://partsandkits.com/ttoroids.html
>
> A fun experiment would be to wind 29 turns of 22 gauge, 24 gauge, 26
gauge,
> 28 gauge, and 30 gauge on 5 different toroids and then measure the
> inductance... (or resonant frequency of the same VFO circuit.)  I think
they
> will be within a few hertz of each other.  The spacing between turns will
> probably alter the outcome more than the wire size.
>
> To perform part of the tests on page 6 you will need an RF probe.  Here is
> some information on them.  (If you don't want to take time to build one
now,
> that's OK.  RF Probes are a good troubleshooting tool.)
> http://www.norcalqrp.org/phprint.php
> http://www.io.com/~n5fc/rfprobe2.htm
> http://www.io.com/~n5fc/rfprobe1.htm
>
> OK... all the components are in... apply power and check for smoke!
>
> When following the test, the wire end of R15, or R16 is the best place to
> measure the base of Q2.  If you installed R17 according to the notes
instead
> of the silkscreen, it is the best place to measure the emitter of Q2.
>
> Here is what I got on the tests:
>
> My SW40+ VFO was running 2.89 MHz.
> I measured 2.5V Peak-Peak on the base of Q2 with my Oscilloscope.  My RF
> Probe measured 1.7V.
> I measured 2.7V DC on the emitter of Q2 with the VFO running.
> I measured 2.3V DC on the emitter of Q2 with the VFO running.
> I measured 1.7V DC on the emitter of Q2 with L1 shorted.
> I measured 2.3V DC on the emitter of Q2 with L1 shorted.  0.6V as
predicted.
>
> My SW30+ VFO was running 2.45 MHz.
> I measured 3.2V Peak-Peak on the base of Q2 with my Oscilloscope.  My RF
> Probe measured 2.0V.
> I measured 3.0V DC on the emitter of Q2 with the VFO running.
> I measured 2.3V DC on the emitter of Q2 with the VFO running.
> I measured 1.7V DC on the emitter of Q2 with L1 shorted.
> I measured 2.3V DC on the emitter of Q2 with L1 shorted.  0.6V as
predicted.
>
> My SW20+ VFO was running 5.03 MHz.
> I measured 1.5V Peak-Peak on the base of Q2 with my Oscilloscope.  My RF
> Probe measured 2.1V.
> I measured 3.0V DC on the emitter of Q2 with the VFO running.
> I measured 2.3V DC on the emitter of Q2 with the VFO running.
> I measured 1.7V DC on the emitter of Q2 with L1 shorted.
> I measured 2.3V DC on the emitter of Q2 with L1 shorted.  0.6V as
predicted.
>
> Take time to read the VFO description and questions on pages 7 to 14.
Glen
> and Mike did an excellent job with this, probably more information than
you
> will ever need :)  I recommend reading this several times in small
segments.
> There is a lot of theory and if your brain works anything like mine, it
will
> overload fairly fast.  (I'm on my 6th or 7th reading, and I still don't
get
> all of it!!!)
>
> If anyone has questions or is having problems... please post to the list
and
> we will try to find an answer.
>
> Melt Solder...  Darrel... K0AWB
>
>
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