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QRP-20 

 21  

FINAL CONSIDERATIONS:  

 

Our earlier discussion of how a watt of RF output can indeed offer satisfying 
communications has several presuppositions:    

 

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. However, you 
also will be interested to know that test QSO's, including DX, were made with 
this Ramsey transmitter using both a mobile whip antenna and simple dipole on 
the balcony of a condo building.  

 

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 watt 
of RF can easily become lost in an incorrectly adjusted antenna matching 
device. The whole idea of this transmitter is to keep things simple and 
economical, so we cannot overemphasize the priority of a clean, efficient 
connection of the transmitter output to a resonant antenna.   
 

TROUBLESHOOTING GUIDE: 

  

 

To put it as kindly as possible, the operations of Ramsey QRP transmitters have 
been field-checked to such an extent that we can assure you that the only 
cause of malfunction will be defective or incorrectly installed components.  

 

If the transmitter does not work, the first step is to recheck ALL assembly steps 
and the quality of all solder connections. In addition, check those too obvious 
things we like to take for granted: cables and connectors, polarity of the DC 
supply.   

 

If the oscillator stage just does not work at all after thorough checking, it  is 
helpful to check your crystal(s) in a test oscillator or other transmitter.   
 
Common trouble spots include:      

 

‰

Incorrect orientation of transistors 

‰

Incorrect installation of diodes 

‰

Incorrect selection of inductors      

‰

Incorrect selection of frequency-dependent capacitors   

 
 

Summary of Contents for QRP20

Page 1: ...cy Front panel switching of TWO channels and includes a crystal for 14 06 MHz the International QRP frequency Excellent and clean keying waveform Built in antenna T R switch Operates on 12 15 volts DC...

Page 2: ...EY 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...

Page 3: ...ram 10 Parts Layout Diagram 11 QRP20 Assembly Instructions 12 Crystal Oscillator Testing 16 Initial Tests 17 Verifying RF Power 18 Maximizing RF Power Output 19 Options for Finishing Project 20 Enclos...

Page 4: ...er amplifier or switching from 25 to 5 watts on your new Radio Shack 10 meter rig or turning back the carrier level control on most modern transceivers For equipment description and contest competitio...

Page 5: ...utput power received from a transmitter 2 Power needs to be increased four times or 400 to result in a true 1 S unit or 6db RST gain 3 Reducing output power down to 25 of previous power should result...

Page 6: ...same path S9 20db 1000 watts S9 10db 100 watts S9 10 watts S8 2 5 watts S7 625 watts S6 156 watt S5 039 watt S4 0087 watt Under reasonably good band conditions particularly at 10 or 14 MHz and on up...

Page 7: ...is almost one million times more powerful than the transmitter used in that historic test WHO SHOULD USE A QRP TRANSMITTER There is a philosophy that Novices should not get started with a very low pow...

Page 8: ...positive bias to the base of Q2 through R8 and 12VDC through choke L4 to the anode of D1 which permits RF to pass through D1 to the filter network while applying negative bias to D2 which blocks RF fr...

Page 9: ...violet brown R10 1 470 ohms yellow violet brown R6 2 1K ohms brown black red R12 13 4 10K ohms brown black orange R4 5 14 15 1 47K ohms yellow violet orange R8 2 1 megohm brown black green R2 3 1 10K...

Page 10: ...QRP 20 10...

Page 11: ...QRP 20 11 QRP20 PARTS LAYOUT DIAGRAM...

Page 12: ...ed some familiarity with general electronics practices and language Therefore you can expect the following procedures to move along with less of the hand holding which we offer for our receivers and o...

Page 13: ...er during transmission and permits the antenna to be connected to the receiver jack during key up conditions To further complete this section of the circuit we now install the first of three 100 uh RF...

Page 14: ...ing frequency S1 permits your choice of any two installed crystals the one that comes with your kit and another which you may add on your own If you plan to add a socket for your own crystal it should...

Page 15: ...re hookups as soon as they are completed This is most especially true with low power transmitters To try out this transmitter you will need the following and we ll offer suggestions about each of them...

Page 16: ...of emitting an RF signal and HARMONICS when and if connected to an antenna It is correct practice to keep your test brief and to identify them with your callsign FURTHER ASSEMBLY The following three...

Page 17: ...ck your connections or have a friend go over them Give extra attention to the work associated with Q2 and Q3 It s always easier to catch an error now before final testing Easier on the cicuit parts an...

Page 18: ...this solid state transmitter does not require tuning or adjustments a periodic power output check up should suffice If you do not own or have access to a low level RF power meter use a trick that is d...

Page 19: ...um reasonable power output without component damage is to run the DC voltage in the 14 to 15 volt range observing a maximum limit of 18VDC IMPORTANT NOTE If you are experimenting with this transmitter...

Page 20: ...iver or transmitter we are happy to give you a couple of additional suggestions and our reasons for them If your first goal is economy and rugged portability you will find that the circuit board can b...

Page 21: ...device The whole idea of this transmitter is to keep things simple and economical so we cannot overemphasize the priority of a clean efficient connection of the transmitter output to a resonant anten...

Page 22: ...QRP 20 22...

Page 23: ...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...

Page 24: ...anual for RAMSEY MODEL NO QRP20 20 METER CW TRANSMITTER KIT 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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