Jim, It should work so long as the sweep circuitry has an X:Y position. I use a Tek 465, and it has that option. Now sampling the RF and audio with these scopes needs a little discussion.
For RF, I like to make a voltage divider to say take my highest power at WD5JKO at 50 ohms (input to tuner) and divide that voltage to about 10 volts peak (could be 1, or 5). Make the lower divider resistor 50 ohms. Some usage of ohms law, and power formulas are required, but nothing tough here. Then use coax to your scope, BNC-BNC. If the coax is very long, and you worry about line SWR, then terminate the scope input with a 50 ohm BNC Female to BNC male feed through termination adapter. As an alternative, if your SWR will remain low, and the power is below 500 watts, then simply use a coax "T" and a scope 10X probe. Stick a banana plug into the "T" with a little piece of wire (1/2 inch) affixed to it so the scope probe can clip on. Use the scope ground clip to the coax cable shield (a small worm drive hose clamp fits nicely on the PL-259 knirled end, and the aligator clip clips to the hanging clamp tang). Another option for some with a Johnson Matchbox as they have a pick-up already included that you can tie your scope into. For the audio, I like to divide that down to about the same 10 volts peak level (could be 1, or 5). For low level modulation all you need is to tap into the audio chain as close to the modulated element as possible, remove any DC, and scale level such that the scope input attenuator can easily handle it. For plate modulation where the plate voltage might be pretty darn high, you need to remove the DC with a suitable capacitor, and divide the audio level way down to the proper level. This might take a bunch of series resistors (limit voltage across each resistor to maybe 500 volts peak), and consider power dissipation per resistor to no more than 50% of the rating. With a high ratio divider you will see phase shift (R-C) increase with increasing audio frequency, and this will corrupt the presented trapezoid. To get around this minimize the capacitive load on the divider, or compensate the divider like is done on a 10X scope probe. Hope this helps, Jim -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Jim Miller WB5OXQ Sent: Saturday, March 18, 2006 11:29 AM To: Discussion of AM Radio Subject: [AMRadio] Use of an oscilloscope to monitor am audio I have a Tektronix model 453a scope and I would like to know how it can be used to monitor transmitted signals. Do I need extra hardware or an interface of some type to obtain the trapezoid pattern? I know some scopes designed for amateur radio have this feature built in so I wonder if my scope can be used for this? WB5OXQ. ______________________________________________________________ AMRadio mailing list Home: http://mailman.qth.net/mailman/listinfo/amradio Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net AMfone Website: http://www.amfone.net AM List Admin: Brian Sherrod/w5ami, Paul Courson/wa3vjb -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.385 / Virus Database: 268.2.5/284 - Release Date: 3/17/2006
