Ramsey Electronics HR40 Manual de Instruções descarregar pdf (Página 20)

FHT-1 • 20

case to the PC board ground plane. The SD1127 power transistor is

ground plane for heat sinking and proper VHF performance. This part is

different from other metal can transistors in that the case is connected

internally to the emitter rather than the collector. This provides much

higher gain at VHF frequencies.

 112. Install C19, 10 pf disc capacitor (marked 10 or 10K).

 113. Install C6, 100 pf disc capacitor (marked 100 or 101).

 114. Install L10, small ferrite bead RF choke you wound earlier.

 115. Install C26, 100 pf disc capacitor (marked 100 or 101).

 116. Prepare an ½ inch long wire jumper from the heavy tinned bus

wire used for winding coils previously. Install this jumper in the L8

location on the PC board. This wire must sit flat against the PC board

and not up above. Believe it or not, this wire is actually an inductor

providing impedance matching into Q6.

 117. Install L7, a 1½ turn coil wound previously. Ensure that the coil is

seated flush against the PC board and not mounted with long leads up

in the air - which would add undesired additional inductance.

 118. Install C11, 100 pF disc capacitor (marked 100 or 101).

 119. Install C20, a 10 pF disc capacitor (marked 10 or 10K).

Wow! You’ve completed most of the RF output section of the Sly Fox

transmitter. Give your eyes a well deserved rest now - only ten parts to go

before the entire unit is ready for testing. After your break have a good hard

look at your creation for solder bridges and misplaced components - these

can be costly errors especially in the RF output section - those components

are expensive! Touch up any questionable connections.

Lastly we’ll assemble the low-pass filter section of the transmitter output and

the power detector section of the transmitter. Please pay particular attention

to component lead lengths while constructing this section, as long leads will

add unwanted inductance to your circuit. To optimize this filtering it has been

placed on a separate circuit board which we’ll build first and then install.

IMPORTANT NOTE

When constructing the Low Pass Filter PC board it is important to

understand that the components will be installed on the “solder” side of

the circuit board, or the side containing the printed circuit traces.

Solder the components on the same side, and then clip the leads as the

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Ramsey Electronics HR40 Manual de Instruções Página 20