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Old April 21st 04, 09:03 PM
Mike Knudsen
 
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Default Questions on Pierson KE-93 rx

The recent auction of a Pierson KE-93 receiver prompted me to get out mine,
which does include the AC PS and speaker unit. ISTR it worked fine 5 years
ago, but now it plays like a bandit on the BC and 1.6 - 3.5 MC bands, but is
dead on all the dual-conversion bands. Also, the S-meter barely works, even
with the powerful reception on the good bands.

The dual conversion is really strange. The 2nd converter is up on the RF deck
as a 4th tube. It has a 2465-KC xtal, but absolutely no tuned circuit between
the 1st and 2nd mixers. Is there any point in doing double conversion without
something in between to cut out the image 910 KC above or below the signal?

Just would like some comments and hints on this odd rx. Not found on BAMA.
All offers of schematics or manul gratefully received.

I'll sweeten the pot with my own observations. First, it's a very compact and
well built radio, more or less a 6-inch cube with 12 tubes crammed in (plus a
heater current regulator a la R-390A). The IF and audio stages are all on a
sub-chassis that can be removed after pulling two plugs (more R390A
inspiration).

The RF deck uses a TV turrent tuner (think mini SP-600) with tuned RF, mixer,
and LO. The turret is bandswitched directly from the panel knob, and is
chain-linked to a drum dial showing only the current band in use. Tuning is
via plain string drive to a 3-gang capacitor and slide-rule needle, and is very
smooth.

RF tube lineup is meat and potatoes: 6BA6, 6BE6, but a 6BA6 LO instead of 6C4.
Another 6BE6 for the 2nd converter.

The function switch includes an SSB position, with a genuine product detector,
though you have to turn down the RF gain for decent SSB audio. A vernier
fine-tuning knob helps with SSB, and BFO pitch is adjustable, using a pot, not
a capacitor. As with most mobile rx, the audio is powerful and the metal knobs
are rugged.

The S-meter is in the speaker/PS unit, and has its own pentode tube to drive
the S-meter from the AGC line, as a "phantom IF" tube. It seems the AGC
voltage coming over the cable from the rx is not good, full of AC, even though
the radio's AGC action is excellent.

This is a dynamite BC and tropical band DXer. Very selective, about as tight
as you can get without sacrificing intelligibility. No selectivity settings,
but what you have is good. Sensitivity is plenty good on these bands,

Odd that there's a current regulator tube (under the chassis, removed and
jumpered out in my set) but no voltage regulator on either chassis. Probably
the mobile supply had one -- anyone ever see that unit?

TIA for any commentary -- Mike K. AA1UK

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