Original Specifications:

 

 

Frequency Range:              144 - 148 MHz

Input Power:                       200 mW - 15 W (MAX)

Output Power:                    80 W Output Power for 10 W input (maximum recommended input power)

Receive Pre-amplifier:        10 dB with 2.5 dB noise figure

DC Power:                          13.8V @ 10 A

Fuse:                                  15 A

Input/Output Impedance:    50 Ohm

Size:                                    8'' x 3'' x 5 1/2''

Weight:                                3 lbs (amplifier only)

 

 

Service Report

 

Date: 2020/07/29

​

Equipment Identification:

​

Type: RF Power Amplifier

Make: Mirage

Model: B108

Serial Number: 4051-281

 

Service Description:

​

- Rectification of the heatsink fins (were bent).

- Re-finishing and painting of the heatsink and bottom cover.

- Overall cleaning of the PCB and components.

- Replacement of the SO-239 connectors (central pin on one of the connectors was lose).

- Replacement of the thermal compound on the RF power transistor.

- Reception Preamplifier and antenna relays cleaned.

- RF sensing SSB delay setting adjusted for ~1.5 sec.

- Tuning of the input and output capacitors for minimum input SWR and maximum output power (see test results below). Tuning frequency: 145 MHz.

- A heavy duty DC + PTT cable was made for this amplifier, using the original style 3-pin Molex connector. 1.5 m-long.

 

Test Results:

- Test Frequency: 145.000 MHz (center of the 2 m band).

- Input SWR: < 1.1 (for PRF IN = 3.5 W).

- Efficiency: 50.6% (VDC = 13.8 V, IDC = 6.9 A, PRF IN = 3.5 W).

 

P RF IN (W)   P RF OUT (W)

1                            30

3.5                     50 (6.9 A)

5                           65

10                      76 (8.6 A)

​

- RF sensing circuit operates flawlessly for input power larger than 2 W. Can become unstable for input power below 1 W (the use of the hard PTT circuit is recommended).

- Reception preamplifier (10 dB) operating normally.