The CE200V is an amateur transmitter manufactured by the Central Electronics
(CE) division of Zenith in 1960. It is somewhat rare. Only about 500 were made
before Zenith pulled the plug on the project.
Click on any picture to enlarge it
The first step was to restore a 50+ year old schematic. Fortunately we had an original to
start with, though it was falling apart and had a few penciled notations. Scanning the
original 22" x 32" sheet, then putting a several hours in with Photoshop gave us a nice
clean digital copy.
Click on the image to the left to download a copy of the final restored schematic. The .pdf will print full size on a D (22" x 34") or D+ (24" x 36" aka architect D) sheet of paper.
Though this large schematic is for the most part accurate, it is not that easy to use, especially when troubleshooting a problem or trying to understand how a particular circuit functions. In order to help us with the restoration, we dissected the full schematic, creating nineteen smaller schematics that were circuit specific. Combined, these nineteen separate schematics make up the entire circuitry of the 200V. We also created a new block diagram of the transmitter in order to serve as a table of contents to the nineteen schematics.
Click on the "Dissected Schematic Set" link to the left to download a 30 page .pdf file of these schematics, mixing scheme block diagrams for each band, a description of the function of each bandswitch wafer and the errors that we've uncovered on the original CE schematic.
The original 200V meter scale was made of a plastic that turned amber over time due to age and the heat from the meter's back light. Virtually every original meter face is almost unreadable because of this and reproduction scales are not available. Therefore, we created our own replacement.
The original meter scale was silk screened onto a piece of 1/32" ivory plastic. We scanned the original, cleaned it up and then printed it on presentation matte photo paper. The printed scale was then glued to a piece of 1/32" clear Lexan plastic. The result is a meter scale that closely duplicates the original as it was before the amber aging took place.
To the left is a the original and our replacement meter scale. Also available, by clicking the links to the left, is the full scale .pdf file for our meter scale, both with the ivory and with a clear background.
The defining feature of the CE 100V and 200V transmitters is their no tune capability. This is accomplished through broadband circuitry. To align these transmitters, a sweep generator is a must. The CE alignment instructions specify a specific demodulation probe circuit to accomplish the sweep alignment. For the alignment the driver and 2nd mixer modules, this probe circuit is connected across a 50 ohm termination resistor connected to the transmitter's RF output (antenna) connector. We concocted our own demodulator for these modules by building CE's circuit and the terminating resister into an old R.L. Drake CB low pass filter that we hand on hand at the shop. The results and the circuit are shown at the left. Though we used 2 watt 100K resistors since we had an excess of these on hand, ¼ watt resistors would have worked fine.
The restoration of this transmitter included an overall cleaning and touchup of the paint, replacement of every paper and electrolytic capacitor and a few out of spec resistors, replacement of eight tubes and a sweep alignment.
To the left is the restored and completely operational transmitter, paired with a National HRO-60 receiver. The box on the top of the transmitter is an outboard audio filter for the HRO-60, a National Select-O-Ject. Both the HRO-60 and the Select-O-Ject restorations are covered elsewhere on this web site. Click here to jump to the HRO-60 restoration and here to jump to the Select-O-Ject restoration
Click on the image to the left to download a copy of the final restored schematic. The .pdf will print full size on a D (22" x 34") or D+ (24" x 36" aka architect D) sheet of paper.
Though this large schematic is for the most part accurate, it is not that easy to use, especially when troubleshooting a problem or trying to understand how a particular circuit functions. In order to help us with the restoration, we dissected the full schematic, creating nineteen smaller schematics that were circuit specific. Combined, these nineteen separate schematics make up the entire circuitry of the 200V. We also created a new block diagram of the transmitter in order to serve as a table of contents to the nineteen schematics.
Click on the "Dissected Schematic Set" link to the left to download a 30 page .pdf file of these schematics, mixing scheme block diagrams for each band, a description of the function of each bandswitch wafer and the errors that we've uncovered on the original CE schematic.
The original 200V meter scale was made of a plastic that turned amber over time due to age and the heat from the meter's back light. Virtually every original meter face is almost unreadable because of this and reproduction scales are not available. Therefore, we created our own replacement.
The original meter scale was silk screened onto a piece of 1/32" ivory plastic. We scanned the original, cleaned it up and then printed it on presentation matte photo paper. The printed scale was then glued to a piece of 1/32" clear Lexan plastic. The result is a meter scale that closely duplicates the original as it was before the amber aging took place.
To the left is a the original and our replacement meter scale. Also available, by clicking the links to the left, is the full scale .pdf file for our meter scale, both with the ivory and with a clear background.
The defining feature of the CE 100V and 200V transmitters is their no tune capability. This is accomplished through broadband circuitry. To align these transmitters, a sweep generator is a must. The CE alignment instructions specify a specific demodulation probe circuit to accomplish the sweep alignment. For the alignment the driver and 2nd mixer modules, this probe circuit is connected across a 50 ohm termination resistor connected to the transmitter's RF output (antenna) connector. We concocted our own demodulator for these modules by building CE's circuit and the terminating resister into an old R.L. Drake CB low pass filter that we hand on hand at the shop. The results and the circuit are shown at the left. Though we used 2 watt 100K resistors since we had an excess of these on hand, ¼ watt resistors would have worked fine.
The restoration of this transmitter included an overall cleaning and touchup of the paint, replacement of every paper and electrolytic capacitor and a few out of spec resistors, replacement of eight tubes and a sweep alignment.
To the left is the restored and completely operational transmitter, paired with a National HRO-60 receiver. The box on the top of the transmitter is an outboard audio filter for the HRO-60, a National Select-O-Ject. Both the HRO-60 and the Select-O-Ject restorations are covered elsewhere on this web site. Click here to jump to the HRO-60 restoration and here to jump to the Select-O-Ject restoration
Restored 200V schematic
Dissected Schematic Set
Driver and 2nd mixer sweep
alignment demodulator