[Amps] Checking relay timing with a scope

[Paul Christensen]

> "I'm trying to figure out how to use it to verify the relative timing of 
> the relays
> in my modified SB-220. Can someone explain at least in general terms
> how to go about this?"

Pete:

Here's a method I use to ensure proper amp relay sequencing:

First, I utilize a dual trace scope (Tektronix SC 504).  Channel 1 is 
DC-coupled and is used to monitor the amp key line closure, and Channel 2 is 
AC coupled and samples the amplified RF from a Bird sampling device.

External triggering is used to keep from having to "chase" the RF waveform 
on the scope's display.  To trigger the scope, I use a microHam CW Keyer 
with a modified output on the second keying port.  Instead of an 
open-collector, I output + 5VDC through a 1K-ohm resistor.  Most scopes are 
looking for a positive-going pulse for the trigger function.  The resistor 
protects the keyer from an accidental short of the +5VDC supply.

With the amp engaged, you can send a string of dits into a dummy load and 
compare the time delay between the amp key line and the RF envelope. 
Moreover, the scope will clearly show how well the keyed waveform is shaped 
and more importantly, whether or not a timing error results in the "hot 
switching" of the amp.

Paul, W9AC




----- Original Message ----- 
From: "Pete Smith" <n4zr at contesting.com>
To: <amps at contesting.com>
Sent: Saturday, June 20, 2009 3:52 PM
Subject: [Amps] Checking relay timing with a scope


> I've only been doing this ham radio thing for 55 years, but until
> this year I never owned or even used an oscilloscope.  I now have an
> old 15-MHz dual trace machine that works fine, and I'm trying to
> figure out how to use it to verify the relative timing of the relays
> in my modified SB-220. Can someone explain at least in general terms
> how to go about this?
>
> 73, Pete N4ZR
> New Articles Daily - the Contesting Compendium at 
> http://wiki.contesting.com
> The World Contest Station Database, updated daily at 
> www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>