Custom Products from Masters Communications

Schematic -   Click Here to download a PDF file of the schematic.

Part List -   Click Here to download the Parts List and Tuning Instructions.

Assembly:
If you bought our kit, assembly can be done by personal choice, but you may find it easier to install the resistors first. Continue with capacitors, making sure not to mix up the values.   Alignment of the transistor is critical - don't install it backwards. Install the SMA connectors if desired. The component leads should be kept as short as possible. Use the notes on the Parts List and the photos for help with component identification and placement. Bob's evaluation article (linked below) is also a good guide for assembly for less experienced builders.

Installation:
This device is intended to enhance the sensitivity of some two-way radio receivers. Older units like the GE MASTR II and Motorola MICOR can benefit in some instances. The preamp requires 12 VDC at approximately 10 mA. The positive lead goes into the hole circled beside the +12V silkscreen. #24 hook-up wire matches the size of holes for the power connections. The minus connects to any ground plane trace, the mounting hole, or the hole beside C6. The mounting hole accepts a standard #4 size screw.

Caution, the mounting hole is at ground potential, so choose your mounting location appropriately!

Use small coaxial cable (like RG174) or the provided SMA connectors and appropriate connectorized jumpers to complete the RF connections into and out of the preamp.

The last photo above shows a coil that's tuned to 220.000 MHz.

The preamp's input is closest to the L1 coil.

Bob's Evaluation Article of the P144 and P440 preamps by Robert W. Meister WA1MIK.
This preamp was designed after Bob's article was written, but most of the information still applies.

If ordering "Assembled & Tested" please email me at the link below and tell me what frequency you'd like the preamp tuned to.

Ordering is available from the main P220 page - (click back).

Email Kevin Custer for ordering information, order by check, or other support of this exciting product.
 

Product of Masters Communications, all rights reserved.
Specifications may change without notice.
Images property of Kevin Custer.
Board layout by Kevin Custer.
HTML August 22, 2020, W3KKC All Rights Reserved!