two of those RF and IF test
internally
known as the “click-box”
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| Click to enlarge (c) Sindre TORP |
Click to enlarge (c) Tim GRIECO |
 | The top-section is a RF-oscillator with 11 fixed frequencies, covering ham bands from 160 to 6m. |
| The mid-section is a IF-oscillator with 9 fixed IF-frequencies used in Drake equipment. |
| The bottom-section is a plate current monitor and fuse-box for connection between the AC-4 power supply and transmitter or transceiver. |
RF/IF Generator/Power Supply Monitor Test Fixture,
internally known as the “click-box”
Bill FROST
Comments
The piece, of test equipment pictured, was produced by the R. L. Drake Company for use in house, by the test department and the service department. These were never produced for resale.
For a small manufacturing plant, the popular 606 RF and IF generators were expensive, especially when you needed 2 to 3 of each for a single production line. The test fixture group designed and produced a single test fixture, that contained crystal controlled RF and IF generator modules. The RF and IF modules could be inserted with the frequencies used to align and test a specific product. In addition, the output level could be controlled by switching in and out attenuator pads of 5 db, 10 db and 20 db, until the exact output level was obtained.
This enabled the tester to select a specific frequency, such as 9.0 MHz to align the IF stage in a TR-4 or 5645 kHz to align an R-4 series receiver IF stage. In a freshly built unit right off the production line, none of the transformers had ever been tuned, therefore initial alignment would require zero attenuation until the transformers were close to being tuned. The attenuator pads allowed the tester to reduce the initial output level, while tuning, until the exact output level was reached, as specified by the alignment procedure. Speaking of “alignment procedure” it has often been thought that the test department used an elaborate alignment procedure, as noted in the T-4X instruction manual. NOT so, everyone used a procedure very similar to that contained in the standard instruction manual.
The RF section of the “click-box” usually had the center frequency of each amateur HF band from 160 meters to the top end of the ten meter band. This made it very easy and very quick to check the sensitivity of a receiver on each band, as compared to using a 606 generator. The tester started at 160 meters on an R-4 series receiver, noted the sensitivity, switched to 80 meters, switched the “click” box to 3.8 MHz, noted the sensitivity, and proceeded to the 40 meter band, through 10 meters.
Since the RF generator was putting out the center frequency on each band, there was no need to tune the VFO to a new frequency. The tester could change from the 160 meter band at 1.8 MHZ to the 80 meter band at 3.8 MHz by flipping two switches or by making two “clicks”. Thus the name “click-box” arose.
The bottom section of the “click-box” housed a large, easily readable, plate current meter. This provided an accurate method of calibrating the plate current meter in a TR-4 series transceiver. A toggle switch to the left of the meter enabled the plate current meter to be used to calibrate the plate current meter of a TC-2 or TC-6. Single unit plate current units were made available to the T-4X series transmitter production line.
In addition to the plate current meter, three front panel fuses allowed the tester to disable the +650 volt section of the AC-4 power supply, and/or disable the +250 volt section, and/or disable the bias section of the AC-4 power supply. The fuses also offered protection to the unit being tested in the event of a short circuit in either the +650 volt section, +250 volt section, or in the bias section.
A green panel light flashed “on” when the T-4X or TR-4, being tested, was keyed, indicating the antenna change over relay was working, more specifically, it noted the linear contact was making contact. A single push button switch allowed the tester to momentarily short the ALC circuit and test for “flat-topping”, distortion, etc. of the two-tone test signal.
The “click-boxes” proved to be invaluable and time saving until the tester forgot to switch over to the dummy load and loaded a TR-4 into it. A small external fuse box was soon added to each “click-box”. It held a 1/16 amp. fuse to protect the attenuator pad section and save the test fixture group repair time.
Bill
Frost
Service Manager
R. L. Drake Company
