Precision E-200-C Signal Generator Restoration

The styling of the Precision Apparatus Company E-200-C signal generator has always appealed to me.

IMG 5786.jpg

For an economical service-grade instrument, it’s also well designed and crafted.

Hand Calibrated Reference Frequencies

Precision supplied a hand-calibrated reference frequency chart with each instrument as part of their “Servicing by Signal Substitution” instruction booklet. Fortunately my example came with the original booklet. 

Servicing by Signal Substitution cover

The net doesn’t seem to have any complete scanned copies of Precision's“Servicing by Signal Substitution” booklet. I’ve scanned mine and put it up in my Liberated Manuals and Books archive: G. N. Goldberger and V. I. Robinson, “Servicing by Signal Substitution”.

Envelope

The booklet came in this envelope, along with …

Guarantee
Guarantee 2

… this guarantee card.


I recently restored my Precision E-200-C. Here’s the story.

IMG 5748.jpg

I’ve already cut out the paper capacitors in the AC line filter.

IMG 5750.jpg

I replaced them with Y-rated safety caps.

IMG 5749.jpg

I replaced the paper caps in the audio sections with modern polyester film capacitors.

IMG 5751.jpg

The band switch arrangement is pretty unique. Precision advertised it as their “Unit-Oscillator” construction. 

IMG 5752.jpg

As a result, there a couple of paper capacitors that are a little difficult to replace.

IMG 5753.jpg

It’s important to preserve the lead dress to keep the generator in calibration.

IMG 5754.jpg

Here I’ve replaced capacitor “C” on the schematic with a new one. (It doesn’t have a number on the schematic, it’s just “C”.)

IMG 5755.jpg

Here I’ve unsoldered one lead of C7.

IMG 5756.jpg

The other end isn’t too bad to get to.

IMG 5757.jpg


IMG 5758.jpg


IMG 5759.jpg

The heater and B+ cloth-covered wiring is all nicely laced.

IMG 5762.jpg

New capacitors for the audio oscillator section, C10 and C11.

IMG 5787.jpg

Rather than remove the electrolytic can to re-cap it, I left it in place but cut off the top with a hobby razor saw.

IMG 5788.jpg

I then drilled some holes in the base for the leads of the new capacitors ...

IMG 5796.jpg

… and soldered them to the old terminals from below. That way I don’t have to disturb the old wiring. Later, I cleaned out the goop from the top of the can and epoxied it back on.

IMG 5763.jpg

The dial is peened to the shaft. You aren’t going to slip this dial to adjust the calibration!

IMG 5765.jpg

Presumably Precision did this so no one would accidentally destroy the hand-calibration made at the factory.

IMG 7449.jpg

The insulation on the original coax cable was cracking, so I replaced it with Belden 8259 coax (it’s a type of RG-58/A). I recycled the original alligator clips and their fabric-covered wire.

IMG 7457.jpg

I made up a cable from a Switchcraft 2501F connector to a BNC. I use it to connect my frequency counter to the high-level RF output of the E-200-C. 

IMG 5786.jpg

All done!


© Steve Byan 2011-2016