On Thu, 10 Feb 2005 4:18 am, Stephen W. Kercel wrote:
I wonder if a brand new MFJ dry dummy load would be that close.
The MFJ dummy load would probably be 51 Ohms after you take it apart and
scrape off the paint that insulates the SO239 from the case. Replacing
the brads with screws also
Steve,
The setup pictured is IMHO overkill, but it covers all bases for any kind of
transmitter. No doubt the ARRL Lab has a semi-permanent setup for this
test, but all that equipment may not be required depending on what you wish
to conclude from your test
The Keying Test Generator is nothing
Don:
Thanks very much. Yes, the ARRL setup is serious overkill. However, I have
a Tek 465, and I thought it would be kind of nifty to try to set it up to
look at my keyed waveform.
As for the matter of running a 50 Ohm source into a high Z scope input, Tek
has a slick solution. They use
Steve,
Regarding the Heath CantennaI have been scratching around with power out
readings recently and after a search of the archives for the word cantenna
yeilded some intersting results.
What I thought over all these years (since 1964) a 50 ohm load was actually
a
68 ohm load after many
a difference, but it is good to double check
anyway.
73,
Don W3FPR
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Stephen W. Kercel
Sent: Wednesday, February 09, 2005 3:31 PM
To: elecraft@mailman.qth.net
Subject: RE: [Elecraft] Keying Waveform Measurement
In a message dated 09/02/05 20:33:27 GMT Standard Time,
[EMAIL PROTECTED] writes:
As for the matter of running a 50 Ohm source into a high Z scope input, Tek
has a slick solution. They use these 50-Ohm 2-Watt terminators that you
apply right at the BNC connector at the scope input
I
Roger:
The topic is extremely timely. I expect there are a lot of Cantennas still
floating around out in Hamdom. One is tempted to naively treat it like a
precision 50 Ohm RF load.
I measured the DC resistance of mine with a DMM and the reading was 46.1
Ohm. I dimly recall doing some noise
Hi Steve,
Check the spec on your scope probe. (try Google). If it can handle the
voltage at high frequencies, that is the easiest way to go. 100 watts into
50 ohms has a peak 100 volts (the peak-to-peak is 200V but the probe only
sees +/-100 volts max).
If you need to make an attenuator, it
Mark:
Yes, you're right; the 465 does have a 20 V/div max using 10:1 probes.
The lesson from you is essentially that when all else fails, read the
instructions. According to my probe manual, the probes are actually good to
500 V up to 10 MHz, then they derate to about 175 V at 30 MHz. They
Bob and Bob:
Thanks to both. The advice is very useful.
73,
Steve
AA4AK
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: Wednesday, February 09, 2005 2:05 PM
To: elecraft@mailman.qth.net
Subject: RE: [Elecraft] Keying Waveform Measurement
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