[R-390] OT: I bought a 'scope

[Dan Merz]

Barry,  my 465dmm manual shows a factor of 2.5 for the uncalibrated range.
This would extend the 50 ms to 125 ms.  I think you're trying to account for
another factor of 5 beyond that.  In looking at the photo ( which is pretty
blurry) I don't know think it's set on 50 ms,  looks more like 100 or 200
ms.  On my scope 50 ms is above the separator between ms and s ranges,  with
50 ms at 9 o'clock and 100 ms and 200 more like 8 o'clock, which is where I
think the time/div is set on the auction picture.   Dan. 

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Barry
Sent: Tuesday, November 10, 2009 6:20 AM
To: r-390 at mailman.qth.net
Subject: [R-390] OT: I bought a 'scope

Listers,

I bought a Tektronix 465M (a.k.a. AN/USM-425(V)1) from eBay (see item
#350273674446). When I saw the trace, I figured the image was shot with a
shutter speed about 1/250 second and with the sweep time set to 50ms, that
would have been about the length of trace shown (approximately 8/100 of the
horizontal scale).

I copied the picture locally and examined its properties.  It turns out the
image was shot at 50ms
(1/20s) so I looked back at the photos and noticed the delay time "UNCAL"
lamp is illuminated.  
Given a 50ms shutter speed and the trace covering approximately 8/100 of the
horizontal scale, then (if I did the calculation correctly), the sweep speed
would be about 625ms.

I'm not all that familiar with this scope, but I assume the sweep can be
slowed to that speed - at least in the 50ms setting.  Is this a correct
assumption?  I ask because I hope the scope is not too broken (if broken at
all).

Obligatory R390 reference?  Well, maybe I'll use it to look at something on
an R390[A] one day...

Thanks,
Barry - N4BUQ

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