User manual RAMSEY RFS1

[. . . ] Before you know it you will be satisfied and have a working project! RFS1 --3 ASSEMBLY OF THE RFS1 1. Installing R2: First, determine the power output of your RF transceiver. Then choose the appropriate value of R2 from the table below (all three resistors have been supplied in this kit). TABLE FOR R2 Power to RFS1 less than 10W 10 to 30W 30 to 100W Value of R2 100 1K 10K 5. [. . . ] Its purpose is to channel DC from the transmission line into the circuit, but block the RF from coming into the power. The larger the value of the coil, the more reactance it has at a particular frequency. So if you are working with HF, the coil provided will not be large enough in value. What we are looking for is a coil with a reactance value larger than 1K ohms. To solve for this part value the formula is a relatively simple plug and chug. Put the value for your coil in "L" and frequency in "F". Remember to take the numerical values of your extensions into account such as Mega = 1 million and micro = . 000001. The formula is as follows: X = 2 * 3. 14 * L * F For example, to find the reactance of the supplied coil in the two meter band, plug in the numbers as follows: 2 * 3. 14 * . 0000022 * 146520000 = 2025 ohms RFS1 --8 So we find the coil has a reactance of about 2K ohms in the two meter band. Rearranging the formula so we can find the value of a coil that has a reactance of 1K ohms at any frequency: L = 1000 / (2 * 3. 14 * F) where F is the frequency you will be operating on. Use this value of coil for both at the power source and as L1 in the RFS1. Note the diagram for jumper setting and parts placement for feeding the power up the transmission line. The coil near the radio end of the coax should be mounted as close as possible to the connections on the coax to prevent unwanted radiation. Block diagram : 12 - 15VDC Choke Value >= L1 . 01uF Center conductor Coax shield JMP1 R RFS-1 Radio RFS1 --9 Hook up of coil near radio : F r o m r a d io . 0 1 u F T o R F S -1 H e a t s h r in k o r in s u la te d w ir e C o il To pow er s u p p ly g r o u n d To pow er s u p p ly + V OPERATING NOTES: 1. If the relay chatters, it is a sign of high SWR, which you will wish to resolve anyway by antenna system or amplifier output adjustments. If the relay action is "sloppy", there is insufficient RF to drive the RFS1 circuit. The following graph depicts the approximate maximum power you should use to operate the RFS1 to prevent overheating or other problems. RFS1 --10 100 W 50W HF 2 m e te r b a n d 440M H z INSTALLATION NOTES If you haven't noticed, the RFS1 has been designed in a way so that it fits well inside of 1 1/2 inch PVC pipe. You can fit it into an existing enclosure, or use a piece of 1 1/2 inch PVC plus two endcaps and some sealant to make a weather tight enclosure. Make sure all grounding connections are as short as possible and all coax shields are grounded as well. Notice the four small holes around where each coax piece is to be mounted. The center conductor of the coax is soldered into the labeled hole, and the four small holes are where you may use pieces of scrap component lead to "strap down" the coax to the board. If you are planning on mounting the RFS1 within a PVC pipe make sure and thread the coax pieces RFS1 --11 PC PC B o a rd Bo ANT ANT Y Y Z Z through the holes in the endcaps before soldering them to the board, especially if the wires are very long!Once you have strapped down the coax to the board with the jumper wire, solder the jumper wire to the braid of the coax on top for a nice, mechanically solid solder joint. Don't overheat when you're soldering; you don't want the braid to melt through to the center conductor and short out a cable. [. . . ] Don't be afraid of telling us that you 'blew-it', we're all human and in most cases, replacement parts are very reasonably priced. MISSING PARTS: Before assuming a part value is incorrect, check the parts listing carefully to see if it is a critical value such as a specific coil or IC, or whether a RANGE of values is suitable (such as "100 to 500 uF"). Often times, common sense will solve a mysterious missing part problem. If you're missing five 10K ohm resistors and received five extra 1K resistors, you can pretty much be assured that the '1K ohm' resistors are actually the 'missing' 10 K parts. [. . . ]