[SOC] 'Scope question

[Paul Playford]

It's good to hear from you Madison.

I consider being a member of SOC an upgrade from my previous rating <grin>.

http://www.oscilloscope-tutorials.com/

Is a good place to start learning about oscilloscopes.  After that just use 
it to keep learning.

My first scope was a military surplus thingy with an a.c. to 5 MHz bandwidth 
and was useless.  But it did keep my workbench from sliding around on the 
floor.  My second scope was a Heath HO-14 (I think that was the model) that 
had a triggered input and was d.c. to 5 MHz.  Useable for rudimentary bench 
work but the biggest problem I had with it was the chassis floated above 
ground and I was always getting shocks from it.

Then I changed jobs and started working with a Tektronix 453A.  I just 
cannot say enough good about that scope.  Fast warm up, the base line did 
not drift, it held calibration, it was rated to 50 MHz +/- 1 dB (Tektronix 
has since changed to +/- 3 dB to agree with other manufacturers), and had a 
nice sharp, easily seen, trace.

The 453A was used by several technicians and I found it very difficult to 
get a trace after other's had used it.  When I finally did get a trace on it 
I took a photograph of the front panel settings and printed it to 8x10 and 
from then on it was easy.

And when we added a second scope to the shop it was a Tektronix 465.  d.c. 
to 100 MHz bandwidth, larger display, but the trace was not as sharp as the 
453A.

When I was at RCA Broadcast I found that the probes are very important.  I 
was adjusting the response of a d.c. to 10 MHz preamplifier with a 465 scope 
and Pamona probes.  Damn thing just would not equalize.  I finally ditched 
the Pamona's and found a set of Tektronix probes and the equalization 
snapped right in.

I see very good Tektronix solid state oscilloscopes at hamfests that can be 
had for $50-$100.  And if you are lucky they come with Tektronix probes.  A 
real bargain.

I once had a customer that pestered my to buy an H-P scope.  The only way I 
could get him off my back was when I asked him "You have a circuit and I 
have a circuit that connects to yours.  The circuit is in trouble and your 
H-P says the problem is on my end, but my Tek says the problem is on your 
end.  Which way do we go"?

For top loading a vertical I think the rule of thumb is the heighth plus the 
length of the top hat wires should equal about 85% of a quarter wavelength. 
Just add some wire to each end of your T and you will be in business.  An 
antenna analyzer is a great help but for 160m you gotta start with wires too 
short and add wire because the analyzers don't go below 1.8 MHz.  Also, if 
you lower the ends of your top hat you will raise the resonant frequency of 
the antenna.  My 160m antenna has 4 elevated radials and 4 top hat wires. 
It starts out as a Hygain Hytower with a 30' stinger and then 4 (ea) 50' or 
so of top hat wires.  I anchor the top hat wire with 1/8" dacron rope to the 
end points of the radial wires for cw and if I should go up to ssb I will 
bring the top hat anchors in about 50 feet.

de Paul, W8AEF

ZF2JL/ZF2TA  FO8DX/FO8PLA  8Q7AA  XZ0A  VU7RG
soon to be TX5C

----- Original Message ----- 
From: "Madison Jones" <w5mj at hal-pc.org>

I am shocked that you are a member of SOC!  I would have expected, with your
talents, that you would be an FOC [or higher, if there is such a thing].

But I have a question for you:  I have an elderly Techtronix 'scope.  It has
been so long since I have used one [mebbe 50 years] that I don't know much
more than how to turn it on.  I do have the book, but it assumes that the
uses knows more than that about its operation.  Where can I find a tutorial
on its basic operation and an overview of what it can do for me?

Other than that, all is well.  Now that the contest season is here [and half
over already] I need to get my antennas in shape.  I put up the rudiments of
your 160 Agatti wire, up 40' or so and out 75' or so on both sides.  I have
resonance on the two elevated radials, but I found the T is only resonant at
2300 more or less, so I must be quite short.  What is a suggested length of
the legs off the vertical wire?  I am limited to 40' vertical.

Regards,

Madison W5MJ
SOC 626 [I think]