40 MTR 20 WATT QRP LINEAR AMPLIFIER KIT Ramsey Electronics Model No. QAMP40 Need a little extra boost for your QRP rig? Believe it or not, 20 watts is only about an ‘S’ unit below a 100 watt rig! This nifty little amp will add some “punch” to any QRP transmitter.
PARTIAL LIST OF AVAILABLE KITS RAMSEY TRANSMITTER KITS • FM10, FM25B FM Stereo Transmitters • FM100 Super Pro FM Transmitter • MR6 Model Rocket Tracking Transmitter • AM1, AM25 AM Transmitters RAMSEY RECEIVER KITS • FR1 FM Broadcast Receiver • AR1 Aircraft Band Receiver • SR2 Shortwave Receiver • HFRC 10 MHz WWV Receiver • SC1 Shortwave Converter RAMSEY HOBBY KITS • SG7 Personal Speed Radar • SS70A Speech Scrambler •TG1 DTMF Tone Grabber • BS1 “Bullshooter” Digital Voice Storage Unit • AVS10 Automatic Seque
Ramsey Publication No. MQAMP40 Price $5.00 KIT ASSEMBLY AND INSTRUCTION MANUAL 40 METER QRP CW POWER AMPLIFIER KIT TABLE OF CONTENTS Introduction to the QAMP40........... 4 How it works................................... 4 Parts list ......................................... 5 Tips and notes ............................... 6 QAMP40 assembly instructions ..... 6 Initial testing ..... ........................... 12 Verifying RF output power ........... 13 Troubleshooting tips.....................
INTRODUCTION The Ramsey QAMP series of QRP power amplifiers are compact 10 to 20 watt RF amplifiers for QRP CW transmitters. These amplifiers are made to be driven by transmitters in the ½ to 2 watt range. Built-in to the power amplifier is a sensitive T-R relay which will switch the unit in and out of the antenna line.
PARTS LIST FOR THE QAMP40 QRP POWER AMPLIFIER CAPACITORS: 1 100 to 220 µf electrolytic capacitor [C1] 1 10 µf electrolytic capacitor [C2] 4 .1 µf disc capacitor (marked .1 or 104) [C3,8,10,13] 2 560 ρf disc capacitor (marked 560 or 561) [C4,7] 2 330 ρf disc capacitor (marked 330 or 331) [C5,6] 2 .001 µf disc capacitor (marked .001 or 102 or 1000) [C11,12] 1 .01 µf disc capacitor (marked .01 or 103 or 10 nf) [C9] RESISTORS: 3 1 K ohm resistor (brown-black-red) [R1,5, TP1] 1 6.
"THE RAMSEY LEARN-AS-YOU-BUILD ASSEMBLY STRATEGY" Take a look at the parts layout diagram. There is quite a lot to the construction of the QAMP40. It's easier than it seems once you get going, especially after you have installed a few of the "landmark" components. Once these "landmark" components are placed, other parts’ positions are referenced to them, and construction goes quite smoothly.
• Insert the part, oriented correctly, into its correct holes in the PC • • board. If helpful, gently bend the part’s wire leads or tabs to hold it in place, with the body of the part snugly against the top side (component side) of the PC board. Solder all wires or pins of the part, whether the 2 wires of a resistor or the 3 or 4 wires of a transistor. Trim all excess wires extending beyond each solder connection, taking care that wire trimmings do not become lodged in PC board solder connections. 1.
16. Install diode D4, 1N4002 style black epoxy diode. Check positioning of the banded end. 17. Install jumper JMP2. Use a piece of scrap component lead wire bent into a "staple" shape and inserted into the board like a component. Jumpers act as electronic "bridges" carrying signals over PC board circuit traces underneath. 18. Install C13, .1 µf disc capacitor (marked .1 or 104). 19. Install L4, 10 µH inductor (green body with brown-black-black bands). 20.
30. Install C12, another .001 µf disc capacitor (marked .001 or 102). 31. Install C8, .1µf disc capacitor (marked .1 or 104). These last four parts (R8,9 and C11,12) form parasitic suppression networks across each transistor to suppress any tendency for high frequency oscillation in the power amplifier. 32. Install C3, another .1µf disc capacitor (marked .1 or 104). Both of these capacitors bypass the center tap of the ferrite transformers to ground.
We're almost finished. All we need to do now is install a few remaining parts that have to be handmade - for that "old-world craftsmanship" touch! We'll prepare all those parts now for further assembly. We give you plenty of enameled wire, but if you mess up, you can get a whole 50' spool of it from Radio Shack (278-1341). 41. Winding L1 and L3 toroid RF coils (two identical units ): Locate 2 of the donut shaped yellow toroid cores provided in the kit.
Tin each end with solder as before. Tin all the way up to the core body. This winding is the primary of transformer T2. Only 2 turns shown for clarity, 8 turns are needed Each lead is about 1” long 44. Cut off another length of wire, 8 inches long. Wind 1 turn through the core, loop out 1 inch, twist together and run one more turn through the core, continuing on in the same direction as before. Tin each end with solder all the way up to the core body.
Secondary leads (wound previously) 1 turn with loop then another turn Twist the loop together tightly (not shown tightly for clarity) 47. Locate the smaller transformer (T2) and install it snugly on the PC board. 48. Install the larger transformer (T1) into the indicated location on the PC board. 49. Install L1, a 19 turn toroid inductor wound previously. If desired, a small dab of hot melt glue, bathtub sealer, or caulk may be used to secure the toroids. 50.
3. Connect a dummy load to J1, the amplifier RF output. In a pinch, a light bulb may be used - see the section, "Verifying RF Power Output." 4. Temporarily install a jumper from the collector of Q3 to ground. 5. Apply power to the amplifier but do not turn on the transmitter. Measure the current drawn by the amplifier and slowly rotate the bias pot, R4, clockwise until you reach a reading of ¼ amp. Do not allow the current to rise above ½ amp.
VERIFYING TRANSMITTER RF OUTPUT The most important thing to know is whether your transmitter is delivering some measurable and reassuring level of RF power. Then you can continue on to adding the QRP amplifier and checking out the whole set-up. Ideally, you have a small RF wattmeter, already inserted in the antenna line, capable of accurately measuring low output power in watts. And it cost you less than what you paid for the transmitter kit. Right? In the words of Wayne from "Wayne's World"...
KB4ZGC on how to make a highly accurate yet inexpensive dummy load and wattmeter capable of showing 1/10-watt differences in RF power. If you use a wattmeter characterized for the HF frequency region, it will not give accurate results at the much higher two meter frequencies, although it will be quite adequate for go/no-go testing.
check are the bias circuitry and RF path through the relay. The amplifier should draw about ¼ amp with no signal applied. If you see more than that, recheck the bias setting (see the section "INITIAL TESTS"). 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.
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. While we believe that the Ramsey enclosure and knob option is a fine value for finishing off your Ramsey kit, we are happy to give you a couple of additional suggestions and our reasons for them.
QAMP-40 • 18
The Ramsey Kit Warranty Please read carefully BEFORE calling or writing in about your kit. Most problems can be solved without contacting the factory. Notice that this is not a "fine print" warranty. We want you to understand your rights and ours too! All Ramsey kits will work if assembled properly. The very fact that your kit includes this new manual is your assurance that a team of knowledgeable people have field-tested several "copies" of this kit straight from the Ramsey Inventory.
QAMP40 20 WATT LINEAR AMPLIFIER Quick Reference Page Guide Introduction to the QAMP40 ...........4 How it works ...................................4 Parts list ..........................................5 Tips and notes ................................6 QAMP40 assembly instructions ......6 Initial testing ..... ............................12 Verifying RF output power ............13 Troubleshooting tips .....................15 Using the QAMP40 .......................16 Parts layout diagram ...................
