[Test-Equipment] Tektronix 492B Question

Wed, 26 Jun 2002 02:32:11 -0700

The '90 Tek catalog has a nice chart that compares the 492BP and the 494AP,
their highest-end model at the time.  The 492BP and 494AP are almost
identical except that the 494AP's frequency stability spec is 10X better
(ages at 1E-7/year versus 1E-6/year for the 492BP); and the 494AP has 10 Hz
minimum RBW compared to 100 Hz for the 492BP.

Everything else is the same, including the front panel controls,
signal-processing and marker features, built-in counter, and so forth.  That
means the 492BP is a vastly better machine than a 492AP or a plain-vanilla
492.

The 492A lacked the later models' ovenized reference standard, counter, and
macro programmability.  The YIG preselector was optional in the 492 and 492A
(option 1), standard in the 492BP and all 494s.

The plain-vanilla 492 is almost the same thing RF-wise, but it has much
less-capable firmware.  It needs options 2 and 3 in order to support basic
digital storage and frequency stabilization, and its center-frequency
readout is only an approximation to the nearest 1 MHz.  The later 49x models
had none of those drawbacks.

Pretty much all of the units shipped after the bare-bones 492 were set up
for GPIB programmability.  You could still buy a non-P model 492A in '87,
but by '90 GPIB was standard across the entire product line.

Some contemporary prices for your amusement:

492 (1984): $21,500
492P (1984): $28,600
Additional cost of options 1, 2, and 3: $9300

492A (1987): $29,040
492AP (1987): $35,340 (+$4K for option 1)

494P (1987): $46,995

494AP (1990): $43,255
492BP(1990): $30,895

Hard to believe the 10 Hz filter and improved crystal oven in the 494AP was
worth an extra $12K, but there you have it.  There really are no other
differences, as far as I can tell from the catalog.

Current eBay prices for all of the above range from 10c to 20c on the
dollar, depending on condition and accessories.

Anyone with a 49x or 275x analyzer with GPIB should check out
http://www.qsl.net/ke5fx for some nifty, free support software (under "An
HP7470A Plotter Emulator for Win32").

-- john KE5FX (current 494P user with a 494AP on the way)

----- Original Message -----
From: "Mark Donaldson" <[email protected]>
To: <[email protected]>
Sent: Tuesday, June 25, 2002 7:48 AM
Subject: [Test-Equipment] Tektronix 492B Question

> I have a Tektronix 492BP spectrum analyzer and was
> wondering what distinuishes this model from the 492
> and/or the 492A? What options were available for the
> 492B? What features were standard on the 492B that
> were options for the 492, if any?
>
> Thanks
>
> Mark WA1QHQ