Ramsey Electronics DAP25 Kit Assembly And Instruction Manual Download Page 10 | Manualshive

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DAP25

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DAP25 PREAMPLIFIER SCHEMATIC DIAGRAM

DAP25 PREAMPLIFIER PARTS PLACEMENT DIAGRAM

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Summary of Contents for DAP25

Page 1: ...e airwaves for signals with this unique kit Omni directional performance no need to point in any direction Learn about antenna theory and what makes the discone an ideal broadband antenna Covers all frequencies between 450 MHz and 2500 MHz and you ll learn why E Z cable connection industry standard F type connector Out performs models costing tens to hundreds of dollars more Super small in size fo...

Page 2: ...apacitance Meter RAMSEY AMATEUR RADIO KITS DDF1 Doppler Direction Finder HR Series HF All Mode Receivers QRP Series HF CW Transmitters CW7 CW Keyer CPO3 Code Practice Oscillator QRP Power Amplifiers RAMSEY MINI KITS Many other kits are available for hobby school Scouts and just plain FUN New kits are always under development Write or call for our free Ramsey catalog DAP25 KIT INSTRUCTION MANUAL Ra...

Page 3: ... 4 Circuit description 8 Parts list 9 Schematic and Parts diagram 10 Assembly instructions 11 Using your DAP25 17 Troubleshooting guide 17 Warranty 19 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR RAMSEY ELECTRONICS INC 590 Fishers Station Drive Victor New York 14564 Phone 585 924 4560 Fax 585 924 4555 www ramseykits com ...

Page 4: ...se early antennas were quite large we ll talk a little more about this later due to the lower frequencies being transmitted Again more recent improvements have allowed us to use higher frequencies with significantly smaller antennas With less and less demand for consumer antennas the market price of these commodities has increased As many of us have discovered even the lowest cost antennas run in ...

Page 5: ...s regular we say that the wave has a frequency of repetition This frequency in fact is the reciprocal of the time it takes for the wave to complete one full cycle mathematically speaking f 1 T By the same token the time and frequency are related by the expression T 1 f The distance in free space that the wave takes to repeat itself is said to be the wavelength and can be calculated using the same ...

Page 6: ...ider the old days of radio The common use of low frequencies meant much longer wavelengths and significantly larger antennas for reception Today s modern electronic devices tend to operate at much higher frequencies and thereby require smaller antennas to operate properly Determining the Resonant Frequency of the Antenna Let s explore another factor in antenna as well as radio design the resonant ...

Page 7: ...he frequency or the length of wire to match a given frequency Antenna Gain Another performance specification common with antennas is their gain usually given in dBi units To understand this concept let s explore the i in the dBi unit as an isotropic source Imagine a point in space as a source of a radiating signal The signal would then expand spherically from the point source If we then move a giv...

Page 8: ...Typical usable VSWR ratios are in the 3 0 1 0 range for commercial available communications equipment while the robust discone design actually outperforms these at many frequencies with a typical ratio of 1 5 1 0 or better A 1 0 1 0 ratio indicates the best match possible resulting in no wasted signal reflection DISCONE DESCRIPTION Getting back to the kit at hand let us apply some of the theory we...

Page 9: ...w noise amplifier could be damaged by injecting RF power into the antenna We recommend the non preamplified version of this kit the DA25 for transmitting applications The good news is if you have not begun assembly yet you may return your kit for full credit towards the non amplified version within 10 business days from original purchase PARTS SUPPLIED WITH YOUR DAP25 KIT 1 3 Qt funnel cone 1 7 in...

Page 10: ...DAP25 10 DAP25 PREAMPLIFIER SCHEMATIC DIAGRAM DAP25 PREAMPLIFIER PARTS PLACEMENT DIAGRAM ...

Page 11: ...he part can be installed by holding it with tweez ers in contact with the tinned trace and re heating the solder see the associ ated diagrams This may go a little against the grain at first but it is by far the easiest method Notice also that when reheating the solder that the iron tip does not come in contact with the tab on the body of the chip component Over heating of this solder tab can cause...

Page 12: ... not as much of a heat sink due to large wires on the components OOPS I bridged that connection This can be a common complaint in surface mount assembly We recommend that you use a solder braid or wick to re move any excess solder usually this can be done without removing the com ponent RAMSEY Learn As You Build KIT ASSEMBLY There are solder connections on the DAP25 printed circuit board Therefore...

Page 13: ...e we ll start with the SMT resistors we packed extras should you need them Remember that the majority of the components will be mounted on the component side of the circuit board and soldered on the top side of the circuit board the side that contains the printed circuit traces Have a look at the component layout diagram to help with your assembly Use the boxes to check off your progress Check all...

Page 14: ...ointed tool carefully un braid about 3 4 of the outer conductor and fan out the loose strands of wire Once this is accomplished trim back about 1 2 of the center insulation Be careful not to cut through the center conductor You will want to trim about 3 4 off of the exposed braid to aid with further installation Carefully tin the cen ter conductor of the cable by adding a small amount of solder to...

Page 15: ... wire supplied with your kit This wire will con nect the circuit board assembly to the disk section of the antenna It is part of the circuit path that connects the disk element to the center conductor of the coaxial cable through the pre amplifier stage Insert through the bottom side of the circuit board through the P2 hole Ap ply a small amount of solder to the top side of the circuit board as sh...

Page 16: ...at to flow the ground con nection completely This may take a little while de pending on the wattage of your soldering pencil 13 Install the disk section of the antenna by passing the three 6 32 screw ends of the stand offs through the disk section of the an tenna while passing the center conductor wire through the center hole of the disk Secure the disk section of your antenna into place with the ...

Page 17: ... radio receiver for a weak station one that is barely breaking the threshold of your receivers sensitivity with your old antenna Note your signal strength indication of the station and proceed to disconnect your existing antenna and replace it with your DAP25 Power up your DAP25 by connecting the other end of the F type feed cable to the power inserted end labeled TO AMPLIFIER Plug in the wall tra...

Page 18: ...t the extensive theory of operation include in this manual and try to apply to your specific problem Have another set of eyes look through your work Here at the shop we have often run into a stone wall of a problem only to have a fellow technician see our obvious error It is sometimes very difficult to see your own mistake taking a break can often solve this common problem Please understand that i...

Page 19: ...ch be assured that the 1K ohm resistors are actually the missing 10 K parts Hum m m I guess the red band really does look orange Ramsey Electronics project kits are packed with pride in the USA If you believe we packed an incorrect part or omitted a part clearly indicated in your assembly manual as supplied with the basic kit by Ramsey please write or call us with information on the part you need ...

Page 20: ...rs Ramsey RTS05 Small Diagonal Cutters Ramsey RTS04 Technician Tool Set Ramsey TK405 ADDITIONAL SUGGESTED ITEMS Optivisor Magnifier Headband Ramsey OPMAG Holder for PC Board Parts Ramsey RTS13 Desoldering Braid Ramsey RTS08 DAP25 DISCONE ANTENNA KIT Quick Reference Page Guide Introduction 4 Circuit description 8 Parts list 9 Schematic and Parts diagram 10 Assembly instructions 11 Using your DAP25 ...

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