WATKINS- JOHNSON 9080-A TUNER, 235 MHz - 1 GHz Part of RS-125 RECEIVER

Description: BACKGROUND: What is a Tuner ? Most receivers today work on the heterodyne principle: if you take two signals, say 1 MHz and 20.4 MHz, and you mix them together, you produce their sum and their difference. Here you get their sum: 2I.4 MHz, and their difference: 19.4 MHz In 1918 EDWIN ARMSTRONG, an American engineer, used this effect to produce a simple radio receiver that could tune into many different radio stations, transmitting on many different frequencies. At the time, you had to build a lot of individually tuned circuits , amplifiers, and filters to swap in and out as you tuned through that wide frequency range. Armstrong first realized that it would be easier to build ONE oscillator, now called the LOCAL OSCILLATOR ( “L.O.” ) then match it frequency to each of the radio stations, then MIX* it’s output with each of the radio stations to produce an INTERMEDIATE FREQUENCY ( I.F. ) which would ALWAYS stay the SAME no matter which station you chose. to listen to. NOW. the rest of the receiver could be built to RESPOND NICELY to just ONE, single frequency,( the I.F. ) FOR EXAMPLE: 1) If we have a radio with an Intermediate frequency ( I.F. ) of 21.4 MHz; and 2) we want to listen to a local AM radio station that broadcasts at 1.05 MHz; 3) we would set the frequency of our LOCAL OSCILLATOR ( “L.O.” ) to 20.35 MHz; 4) Then we would MIX it with the station’s signal at 1.05 MHz; and we would get: 5) Their SUM: ( 20.35 MHz + 1.05 MHz ) = 21.4 MHz [ç our I.F. ] and also: 6) Their DIFFERENCE : ( 20.35 MHz - 1.05 MHz ) = 19.30 MHz we can ignore this frequency, 7) because we only have to look at the I.F. 21.4 MHz from this point on.Now, if the user wants to listen to another station, say at at 800 kHz ( 0.8 MHz ) he would set the LO to 20.6 MHz, and get 0.8 + 20.6 = 21.4 MHz Today, most receivers work this way However, for a unique US Government project in the 1960s/1970s, WJ built the RS-125 system . There were only a limited number produced. This system consisted of one regular receiver the VLF-356, covering 1 kHz to 1 MHz , and these individual tuners: HT-10 [ 1-10MHz ], the VT-11 [10 -30 MHz ], the VT-30, [ 30-260 MHz], and the Ut-1000 [ 250 MHZ - 1 GHz .] With the tuners now handy, and separate from the rest of this receiver system, we now have a MODULAR system. This has certain advantages.VERSATILITY: Now, the tuners can be connected, one at a time, to the remainder of the receiving system, a unit that W-J calls the “ Demodulator". It only has to work at ONE FREQUENCY: the I.F. Besides being bigger, heavier, and more cumbersome and expensive than all the receivers built the ”NEW” way, This receiver, more than 50 years later, still has practical advantages. With the tuners’ outputs being separate and easily accessible, the users can customize this receiver, optimizing it's performance for the signals that they are seeking or trying to analyze.The user can buy 2 or 3 ( or more ) of these modular tuners, connect some of them to different antennas, point some in slightly different directions, and tune some to slightly different frequencies. The user can then combine the IF outputs: adding some and subtracting others ( noisy ones).This tuner covers the 235 MHz to 1 GHz frequency range. Other tuners take you as high at 12 GHz. and allow you to change bandwidths as you tune, unlike a modern automated receiver or network analyzer. It is easy and straightforward to use.RESISTANT TO ENVIRONMENTAL ELECTROMAGNETIC EFFECTS: Since it contains no integrated circuits, it is resistant to high altitude electromagnetic pulse (HEMP/ EMP ) attacks as well as high energy radio frequency sources (HERF guns) and types of electromagnetic interference ( EMI ), including intentional electromagnetic interference ( IEMI ), For over thirty years, this unit has been used strictly by qualified professionals, and stored in a testing laboratory under controlled temperature, humidity, and Barometric pressure ( see figure 1 ) It has not been subjected to shock or vibration, and it has never been used for on-site [ field ] testing. EASY TO FIX: The modular design of the RS-125 system makes it easy to fix. You can fix many problems yourself simply by keeping spares of the most important modules and replacing them when ( AND IF ) they ever go down. It is clear that the manufacturer. WATKINS-JOHNSON, deliberately designed this unit to be easy for the user to fix. As shown in photo 3, removing the top cover reveals a set of alignment tools thoughtfully provided for this purpose. Modern designs might be smaller, lighter, and easier to automate, but they are easily damaged and then must be sent across the country to be analyzed by the manufacturer. We have several tuners and 125 systems for sale. This unit works and is vintage electronics. We cannot accept returns. If you purchase more than one of our items we will combine orders and adjust the shipping. We welcome all questions. PLEASE NOTE: This equipment series was designed for use by the government of the United States, that is why the model numbers are different from the usual WJ equipment line.

Price: 400 USD

Location: Herndon, Virginia

End Time: 2024-12-21T15:59:30.000Z

Shipping Cost: 25 USD