[Elecraft] It can be done! - Bench equipment

[Don Brown]

Hi All

Here are some thoughts I have on bench equipment. The minimum requirement=
 is a DVM, a power supply, a soldering iron/station and some hand tools. =
you may need more than one power supply. One medium to high current (say =
5 - 25 amps) to power 12 volt stuff like radios. A fused car battery or h=
am type power supply could handle this.  An adjustable supply with a curr=
ent limit for experimenting is also nice to have (say 0-25 volts at 1 or =
2 amps). If the DVM doesn't have current ranges get a .1 ohm and .01 ohm =
5 or 10 watt 1% resistor to use as a shunts for your meter. Even if your =
meter has a current range its is safer to use the shunt resistors. If you=
 make a mistake in current measuring you will blow the meter fuse or the =
internal meter shunt. With the resistor just put in series with the circu=
it and measure the voltage drop. The .1 reads 1 amp at 100 mV and the .01=
 reads 10 amp at 100 mV easy math.

One of the handiest and simplest additions I made to my bench many years =
ago is a 3/4" x 1/2" deep trough along the edge of the work bench. I moun=
ted a 2x4 flush with the front edge of the bench and used a router to cut=
 the trough. This trough catches any small parts before they can fall off=
 on the floor and you can sweep lead clippings from the bench into the tr=
ough and then into the trash can off the end of the bench.

A good lamp, chair and magnifier is also needed. I use a 7 power hastings=
 hand magnifier from Edmond Scientific but that's just my preference. You=
 may find something else works better.

There are a lot of scopes out there new and used. I think I would look at=
 some of the Tektronix or HP used analog scopes and would go for 100 MHz =
or better. There are some real bargains. Just be sure the CRT is good. Th=
e way to tell is to check for double peaking. Turn down the intensity the=
n watch as you increase the intensity. If the intensity increases then di=
ms as you turn up the control then the CRT is not up to snuff. It may sti=
ll have some life left, just be cautious, and the price should reflect th=
is. Also check the attenuators. Connect to the calibrator wiggle the V/Di=
v knob and make sure the trace is steady and the amplitude reduces proper=
ly as you change ranges then check the time base knob the same way. Then =
connect the input to a sine wave and adjust the V/Div for several divisio=
ns of amplitude centered. Adjust the trigger in normal mode so the start =
of the sine wave just crosses the center of the screen. Switch from plus =
to minus trigger and the start of the sine wave should cross the center l=
ine at the same point just in the reverse direction. Reduce the amplitude=
 down to .2 divisions you should still be able to trigger on the sine wav=
e.

At this point you have a well equipped bench and most other stuff is just=
 nice to have if you can afford and justify it. Generators are easy to bu=
ild or use your transmitter. There are frequency counter kits, Watt meter=
 kits and function generator kits at low cost.

You don't have to spend a lot of money to have fun although you can spend=
 a lot if you can and want. Same as with almost any hobby.

Don Brown
KD5NDB
----- Original Message -----
From: Tim and Nancy Logan
Sent: Wednesday, April 10, 2002 9:35 AM
To: Elecraft
Cc: tentec reflector; QRP-l; George, W5YR; Bill Golden
Subject: [Elecraft] It can be done!

Hi folks - I received a lot of replies from good folks when I went
shopping for an oscillscope on a small budget. I wanted to let all know
that I received my Tektronics 465M today via Ebay which I paid about
$130 for. An engineering friend helped me check it out and it works
perfectly. So I just wanted you budding experimenters on a low budget to
know that it can be done. A function generator is now on the way from a
VERY reliable ebay source - it ran about $175 and can take care of most
needs. Just thought I would share this with those who might be
interested. 73/Tim Logan NZ7C


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