"Ignoramus7994" wrote in message
...
| I just won 2 lots consisting of total of 10 Harris 7223 RF amplifiers,
| at a liquidation auction. I would like to test them a bit.
|
| They are rated 250 watt output.
|
| I have a signal generator, a 25W power meter, and an oscilloscope.
|
| They are in their shipping boxes, looking pretty good and rated in
| military condition A4, which is like new.
|
| What could I test to make sure that they are in a perfect condition
| indeed?


A crude test is to connect a 250 W light bulb across the output and run them
up to power. Better would be an electric heater element, and better still a
real dummy load of the correct impedance.

For the first two, be aware that you don't have the right impedance so you
can't put 250 W into the load. Also, the load will not be constant across
the frequency range. You'll need to do some calculation to figure out a
reasonable power level.

You might want to ask for further ideas on a ham radio or Heathkit mailing
list.

N

"Ignoramus24505" wrote in message
...

| Thanks for your suggestion. What I am leaning towards is this. To find
| some place that can rent me a bigger power meter and a spectrum
| analyzer and a clean signal generator (unfortunately, as I said
| earlier, my signal generator works, but produces broken sine waves).
|
| That way I could assure that 1) the amplifier produces sufficient
| power, 2) that it does not distort the signal.
|
| The question is, how to find such a lab.

Look for someone who services two way radio or marine electronics (often has
an antenna on the roof). They may be able to suggest someone.

NM

"Ignoramus24505" wrote in message
...
On Sun, 14 Nov 2004 18:16:50 GMT, NSM wrote:

"Ignoramus24505" wrote in message
...

| Thanks for your suggestion. What I am leaning towards is this. To find
| some place that can rent me a bigger power meter and a spectrum
| analyzer and a clean signal generator (unfortunately, as I said
| earlier, my signal generator works, but produces broken sine waves).
|
| That way I could assure that 1) the amplifier produces sufficient
| power, 2) that it does not distort the signal.
|
| The question is, how to find such a lab.

Look for someone who services two way radio or marine electronics (often
has
an antenna on the roof). They may be able to suggest someone.

I found some electronics rental place nearby, will talk to them on
Monday.


I doubt that you really need a spectrum analyzer. If they make rated output
with rated drive, they are most likely to meet harmonic rejection
specifications. Power supply, dummy load, wattmeter, and a signal source
should do it. Also, it would be nice to be able to monitor the supply
current.

"Ignoramus24505" wrote in message
...

| I will try to win a military lot with dummy loads that's coming up, I
| really need one for my home lab and will sell the rest of them. I
| could them pick up the amplifiers and the dummy loads in one trip. Is
| a wattmeter separate from a dummy load? IOW, a wattmeter does not have
| its own load, it plugs in between the signal source and dummy load, is
| that right?

A wattmeter may or may not have a dummy load built in for convenience.

| That Harris, as I just learned, has its own display that displays
| watts. So, if I have a dummy load, I would not even need a power
| meter, if I am to trust Harris's display. It would be nice, although
| by no means required, to compare Harris's own idea of its output with
| an expernal power meter. I have not seen a 500W power meter anywhere
| yet though.

Where would you dump the heat? Heath made the Cantenna, a dummy load filled
with oil that could be used for testing.

Look for (Palstar DL2K Dummy Load) or (Heathkit Cantenna) for more. See
http://www.geocities.com/the_loaded_.../project2.html as an
example.

NM

I will try to win a military lot with dummy loads that's coming up, I
really need one for my home lab and will sell the rest of them. I
could them pick up the amplifiers and the dummy loads in one trip. Is
a wattmeter separate from a dummy load? IOW, a wattmeter does not have
its own load, it plugs in between the signal source and dummy load, is
that right?

Yes, there are dummy loads with built-in wattmeters but probably not
appropriate for your project. As to RF wattmeters,
http://www.radiodan.com/Henry/misc/bird.htm

That Harris, as I just learned, has its own display that displays
watts. So, if I have a dummy load, I would not even need a power
meter, if I am to trust Harris's display. It would be nice, although
by no means required, to compare Harris's own idea of its output with
an expernal power meter. I have not seen a 500W power meter anywhere
yet though.

Again: http://www.radiodan.com/Henry/misc/bird.htm


Also, it would be nice to be able to monitor the supply
current.

A great idea, in fact, I own a kill-a-watt inline electric meter, it
meters watts, volts, hertz etc.

Sounds like a fun project! Good luck!