Ramsey Electronics STC1 Instruction Manual download pdf (Page 19)

FM25B • 19

 89. Install VR1, the 78L05 +5 volt regulator. This part looks like a transis-

tor and like a transistor, it must be place correctly to work. Follow the parts

layout diagram and PC board silkscreen for orientation. Solder all three

pins.

 90. Install C1, the last 10 µF electrolytic capacitor. Check polarity before

soldering.

 91. Install C4, the other 100 µF electrolytic capacitor. Do I have to remind

you about polarity again?

 92. Install R4, 470 ohms (yellow-violet-brown).

 93. Install R1, 10 ohms (brown-black-black).

 94. Install Q1, the last 2N3904 transistor. Again, be sure it is placed cor-

rectly before soldering.

That’s it! But before you grab the power supply and fire up the FM25B, take a

moment to check over your work. Check to be sure that all the parts are in-

stalled and the polarity sensitive ones are placed properly. Look for solder

joints that could be questionable and need a quick touch-up. Also look for po-

tential solder bridges; the parts layout diagram can help with that. You may

want to hurry and get the kit powered up but anything you find now will save

you a lot more trouble later. Unless you like the smell of smoke and the sound

of things exploding! It’s worth the few extra minutes. Looking over the PC

board is the first step our Ramsey technicians complete when testing units

here at the shop.

ASSEMBLY INSTRUCTIONS FOR CUSTOM CASE

 1. Note that the case halves fit together only one way. Be sure you’re in-

stalling the board so that the case halves will fit together and the antenna

hole will be in the right spot. Insert the board into the case with the knobs

and LED extending through the holes in the front panel.

 2. Raise the rear portion of the PC board and extend the jacks through the

rear plastic plate. Insert the plate into the grooves on the base tray.

 3. Secure the PC board to the bottom base tray with 4 short Phillips head

screws.

CHOOSING AN OPERATING FREQUENCY

(A) It really is NOT sufficient to just "check" the FM band for an empty fre-

quency, using the FM portable radio closest at hand. It is your responsibility to

carefully research what FM stations can be listened to with a good system

within the transmitting range of your FM25B. This is especially important in the

low end of the FM broadcast band (88-92 MHz), where there are numerous

medium power National Public Radio stations. You may not be aware of these

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Ramsey Electronics STC1 Instruction Manual Page 19