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QAMP20 • 16  

If you hear an AC hum on the transmitted signal, usual causes are RF getting 
back into the power supply or a bad VSWR on the antenna. 
 
These short checks in no way detail any and all problems that can rear their 
ugly head, but should get you on the way to solving most errors. We'd like to be 
able to foresee a problem a builder may encounter, but the sheer number of 
parts and the permutations and combinations of installing them makes any list 
of precise, exact solutions impossible. If you run into a roadblock, gather all your 
thoughts and information and give a call to the factory for some help. If you elect 
to enlist the help of a local expert, great...but be sure the expert is qualified (no 
need for having someone lead you down the wrong path)! Remember: You may 
always return the kit for factory service, and there's no charge if the problem is 
our fault. See the warranty on the last page of this manual. 
 

USING THE QRP POWER AMPLIFIER 

 
Hooking up and using the amplifier is easy: Just connect your existing 
transmitter to the QAMP input and the antenna to the QAMP output. A resonant 
antenna is an absolute requirement for QRP operation, and an amplifier is not a 
"band-aid" for a poor antenna system! 
 
For maximum performance, a QRP station must include the following: 

1

A resonant antenna (dipole or quarter-wave vertical); 

2

Good quality coaxial feedline and connectors; 

3

An effective earth ground.   

 
We cannot expect good results from low levels of RF output if the power gets 
wasted in lousy coax, corroded connections, or poor antennas. 
 
If you elect to use an antenna tuner, it is extremely important that you  
understand exactly how to use tuners and what they can and cannot do. A few 
watts of RF can easily become lost in an incorrectly adjusted antenna matching 
device. The whole idea of a QRP station is to keep things simple and 
economical, so we cannot overemphasize the priority of a clean, efficient 
connection of the amplifier output to a resonant antenna.     
 

ENCLOSURE RECOMMENDATIONS 
 

Your finished amplifier can be installed in a variety of enclosures of your own 
design and choosing. You might be planning to combine several Ramsey circuit 
kit boards in a single enclosure. Use of the inexpensive and attractive Ramsey  
case and hardware set will give your unit that nice finished look and increase its 
resale value. These sturdy black instrument cases are supplied with neatly 
lettered front and rear panels, switch knobs, rubber feet and mounting screws. 
  

Содержание QAMP20

Страница 1: ...elay automatically switches between receive and transmit Runs on 12 volts DC at 2 to 4 amps ideal for field day or battery operation Multistage low pass filter for a clean signal Operates all modes CW...

Страница 2: ...r 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 a...

Страница 3: ...ctions 7 Initial tests 12 Verifying RF output power 13 Troubleshooting tips 15 Using the QAMP20 16 Parts layout diagram 17 Schematic diagram 18 Ramsey kit warranty 19 KIT ASSEMBLY AND INSTRUCTION MANU...

Страница 4: ...P amplifier is very simple with most of the magic being done by just a few parts the pair of MOSFET transistors and the ferrite wideband transformers Transformer T2 matches the 50 ohm amplifier input...

Страница 5: ...70 ohm resistors red violet brown R8 9 1 51 ohm resistor green brown black R10 1 2 2 K ohm resistor red red red R11 1 5 K potentiometer marked 502M R4 SEMICONDUCTOR DEVICES 1 Zener diode 6 2 volt gray...

Страница 6: ...the problems we find here at the factory are due to faulty assembly no matter how experienced the builder may be it s especially tough to tell a 30 year experienced ham that he goofed Before you run...

Страница 7: ...RCA phono jacks Solder all 4 pins on each securely as these connectors will be subjected to some stress when coax cables are connected to them 3 Install J3 PC mount DC power jack 4 Install relay K1 N...

Страница 8: ...or proper operation Generally capacitors have their lead marked with a black stripe while PC boards have the hole indicated 22 Install D1 6 2 volt Zener diode gray body with a black band This diode pr...

Страница 9: ...nother 180 f disc capacitor marked 180 or 181 38 Install wire jumper JMP1 Use a scrap piece of component lead wire 39 Locate the MOSFET power transistors and prepare the leads for insertion into the P...

Страница 10: ...t or a magic marker We don t want to confuse it with the other two toroid coils wound just before 43 Winding T2 Locate the smaller of the two 2 hole ferrite cores Cut off one 11 inch length of enamele...

Страница 11: ...le or too much then you have not wound the core correctly Tin each end with solder as before Tin all the way up to the core body 46 Cut off another length of wire 9 inches long Wind 1 turn through the...

Страница 12: ...for testing you ll need the following 1 Multimeter capable of measuring voltage and current 2 12 volt DC power source of at least 3 amp capacity 3 Suitable dummy load and resonant antenna 4 QRP trans...

Страница 13: ...r transmitter with good amateur practice YOUR POWER SUPPLY AND RF OUTPUT POWER For optimum performance one or two volts of extra DC supply power can make quite a difference in any RF power amplifier F...

Страница 14: ...m 2 to 25 volts RMS depending on various factors Typically 1 watt power levels are achieved in the 5 to 7 volts RMS range 5 watts at 12 to 15 volts and 10 watts at 20 to 25 volts A good test bulb for...

Страница 15: ...e for this occurring Any prolonged parasitic emissions may also overheat and destroy other components in the amplifier TROUBLESHOOTING HINTS The QRP power amplifier is very straight forward and simple...

Страница 16: ...r QRP operation and an amplifier is not a band aid for a poor antenna system For maximum performance a QRP station must include the following 1 A resonant antenna dipole or quarter wave vertical 2 Goo...

Страница 17: ...keyer etc The controls are easily mounted at one end of such a box It may be necessary to cut away the molded posts which secure the tape itself These storage boxes come in several styles so pick one...

Страница 18: ...QAMP20 18...

Страница 19: ...h 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...

Страница 20: ...Quality Electronics Kit was designed and packed in the USA REQUIRED TOOLS Soldering Iron Ramsey WLC100 Thin Rosin Core Solder Ramsey RTS12 Needle Nose Pliers Ramsey MPP4 or RTS05 Small Diagonal Cutte...

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