Watkins Johnson DM-4B Demodulator & CEI / WJ CV-1750/U 235

Description: Nice Watkins Johnson Model DM-4B (S/N# 188) demodulator, 21.4 MHz input, accepts 4 plug-ins, 6 MHz bandwidth, BFO, squelch, tuning and signal strength meters, 3 audio outputs: 100mw into 600 ohm, built-in speaker, 3 video outputs: analysis, recorder & tracking. The 4 plug-in modules are 2 each Model IFD-500C with 30KHz / 100KHz / 250KHz switchable bandwidths, 1 each Model IFD-2000B (we believe, tag is faded) with 100KHz / 600KHz / 1MHz switchable bandwidths, and 1 each Model IFD-4000B (we believe, tag is faded) with 500KHz / 1MHz / 2MHz switchable bandwidths. This item is in good+ overall physical condition except for having 2 or 3 knobs that need replacing since they are cracked or damaged. There are 4 tools included that are located under the top cover. I plugged the unit in and the power indicator comes on and I get a hiss in the speaker. This unit is fully transistorized. Included with this item is a CEI (Watkins Johnson) CV-1750/U (S/N# 40) Converter, Frequency, Electronic. The nomenclature tag also references the following: Contract# DA19-119AMC-02153(X) This unit covers the frequency range of 235 – 1000MHz in 2 bands (235 – 500MH and 490 – 1000MHz) and converts this to 60MHz. The 60MHz was fed into a WJ / CEI Model 977 30 – 300MHz receiver tuned to 60MHz and then the 21.4MHz I.F. output was fed to the DM-4B demodulator for processing. Unfortunately we no longer have the 30 – 250MHz receiver (It is NOT included, we do NOT have). Therefore, in order to use this converter with the DM-4B, one would have to fabricate a 60MHz to 21.4 converter or procure a receiver as mentioned. The CV-1750/U was constructed in the late 1950’s, early 1960’s with hybrid technology. It has a few transistors but most if not all of the RF active devices are subminiature vacuum tubes. I believe the VHF tuner uses Nuvistors, and the UHF tuner uses Nuvistors or small ceramic vacuum tubes. I did NOT open the tuning units to verify but transistors were not advanced enough to do these functions when this unit was designed. The CV-1750/U is in fair – good overall physical and cosmetic condition. There are some scratches & marks on the front panel and a few fasteners are missing from the cover. In addition, it is in need of a new power cord. I plugged it in and it lights up as it should. I did not further testing of this item. Since these units may need Calibration and/or repairs and due to their age, I am selling these items for PARTS or REPAIRS per eBay protocol and as USED, Strictly AS-IS. The pictures form part of the description, and my descriptions are a “Best Effort” so please bid accordingly. These items represent the state of the art, excellent engineering and utilized the highest quality American made components that were available at the time they were designed. They are well packaged in a 24” X 22” X 15” box that weights 55 LBS. I ship within 3 days of receipt of funds. Item will ship upon receipt of guaranteed funds. PayPal Will ONLY be accepted from users with a CONFIRMED ADDRESS * AND * the Item MUST ship to that SAME ADDRESS.

Price: 439.94 USD

Location: Laguna Hills, California

End Time: 2024-09-18T15:30:01.000Z

Shipping Cost: N/A USD