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linearity control interacts with the center frequency control and adjusts the linearity of the sweep of the local oscillator. The if amplifier and power supply are of the standard variety so time and space will not be consumed in outlining their function. The CRT controls are similar to those used on the Modulation Analyzer.


The receiver was modified by adding a 10 mmfd condenser or less to the plate of the stage you desire to use. Connect one end of the condenser to the plate and the other end to the center conductor of a short piece of KG-58/u coax. The shield of the coax should be left floating or above ground at the condenser end. Install a phono plug 011 the receiver arid attach the other end of the* coax to the phono plug and ground the shield at the plug end. The alignment of the receiver is generally not affected if the coupling condenser is small This completes the receiver modification.

The power transformer should be positioned as far from the CRT as possible to reduce the affects of electromagnetic interference. In some eases it may be necessary to rotate the transformer to further reduce the interference.

The layout of parts is rather critical due to the limited space available, so care should be taken before holes are drilled. Use plenty of terminal strips under the chassis to facilitate wiring. The controls on the panel were located similarly to the controls on the Modulation Analyzer and will allow full control of the display. A temperature compensated condenser should be used for the mixer-oscillator circuit. This will reduce drift during warm-up and operation. However, there are controls on the front panel that will also compensate for drift. The case should be well perforated for adequate ventilation.

It may be desired to build the Modulation Analyzer and Panoramic Spectrum Analyzer into one unit. This would make a very attractive and much talked about accessory.


After the unit has been completed and wiring double checked, give it the smoke test by applying power. The filaments and pilot light should illuminate. Allow several minutes for warm-up before alignment. Remove the rf amplifier and reactance modulator tubes and eon nect a signal generator to the grid of the mixer-oscillator. Set the generator frequency to the if frequency of the p ana dap tor. Connect a VTVM or scope across the detector load resistor and tune the if transformers for maximum output. Adjust the panel controls until the base line appears approximately 1/3 of the way up from the bottom of the CRT. Place the sweep, center frequency and linearity controls to approximately the mid-position. Replace the rf amplifier and resistance modulator tubes and connect the signal generator to the panadaptor input. Set the generator frequency to the input frequency of the panadaptor.

Now align the oscillator frequency until a pip shows on the center of the base line on the CRT. If the signal generator frequency is varied back and forth, the pip will also move back and forth across Ue CRT. The rf transformers can be stagger tuned to produce as linear an output when observed on the CRT as possible, while varying the generator frequency.

The oscillator frequency may be determined with a GDO or by the use of a receiver. Place a short antenna, from the receiver, near the coil and tune receiver and/or oscillator until the signal is heard. The oscillator can now be tuned to the desired frequency. The second or third harmonic may be used, if necessary, for receiver reception.


After the unit has been aligned, connect the coax Jumper cable from the panadaptor to the receiver. With receiver turned on and then tuning across the bands, you will get an idea of the type ot presentation to expect on the

Radio Experimenter

CRT. You may desire to touch up the align- | ment as a final adjustment

The height of the pip will double when the modulation is 1.00Carrier shift is indicated by a sidewise movement of the pip under modulation. Splatter is evident when smaller pips appear and disappear on either side of tlie received signal when modulated. Zero beating is simply accomplished by moving the pip from your \TO to coincide with the received signal. Out-of-band operation can be eliminated when using a crystal calibrator and the pariadaptor. You can immediately see if your signal is In or 'Out" of the band by its position with respect to the crystal calibrator signal. After calling CQ you can see the signals replying (within limits) without touching vour receiver. The face of tlie CRT can be

•r calibrated by using an overlay or thin strips of tape as markers.

The signal may be monitored by using a pair of headphones and by adjusting the center frequency or receiver the desired signal can be heard.

It is also a considerable aid for SSI3 and C\V operation. It is the writer's opinion that it could be used in copying code visually for those that are deaf.

When chasing DX? the signals are some times quite weak. As you are tuning across the band you will see the signal before you hear it thereby tuning more carefully when you approach his frequency. If the DX signal should take a dip at the time you tuned to his frequency, chances are you would have missed a rare one without tlie pan adaptor.

The writer has worked 125 countries on phone in approximately two years and quite a few of these are attributed to the use of the panadaptor. It is a very versatile piece of equipment and will also enhance the beauty of the shack.

The writer wishes to thank Mr. Dick Azim, K0JEJ, for the fine job of photographing the equipment . , + W0BMW

Il V// pay SI each i or ideas good enough to print.

, . . coaxial cable made lower loss by silver plating the surface of the inner conductor since most of the skin effect loss is on this surface. 1'inning increases skin effect losses, silver reduces it. . ^ - W2WLR

New Heavy Duty RFI Suppression Kit For Mobile Radio

OPERATORS can now enjoy clearer, less tiring mobile communications at longer ranges.

Sprugue's Type SK-1 SUPPRESS! KIT provides effective R-F Interference suppression—at moderate cost—up through 400 mc. Designed for easy installation on engines with 6-volt or I2-volt generators, the Suppressikit makes possible high frequency interference control by means of Sprague's new, extended range, Thru-pass-capacitors.

The components in the SK-1 arc neatly marked and packaged, complete with easy-to-follow installation instructions.

The generator capacitor is a heavy-duty unit rated at 60 amperes, and will operate at temperatures to 125°C (257°F). ¡ here's no chance of generator failures from capacitor "short outs/? as with general purpose capacitors. The Thru-pass capacitors for use on voltage regulators are also rated at a fuli 60 amperes.

Containing only 5 easy-to-install capacitors, the Deluxe Suppressikit is a well-engineered kit. The net price is a little higher than that of many thrown-together kits, but it saves you so much time and aggravation it's well worth the slight extra cost.

For additional information on the Type SK-1 Suppressikit see your Sprague Electronic Parts Distributor.

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