RF FAQ

Why does the TPO on my FMi C Series transmitter seem to drift and not stay at 100%?
If the power on your FMi C Series transmitter seems to drift up or down in output power over time or whenever my air handling system turns on, the problem m...
Tue, 8 Oct, 2019 at 1:18 PM
Why doesn't my FM-T or FMi-T TX have RF output? The readings appear ok, except for 0 PA current.
Remove tube and check the filament rings to ground; normally the Ohm meter will indicate zero Ohms. If the filament rings indicate an infinite resistance, c...
Tue, 8 Oct, 2019 at 1:23 PM
Why doesn't my FM-T or FMi-T TX have RF output? The syptoms: high screen Voltage and high IPA VSWR.
Most likely issue is that R4 (10 watt 1.5 Ohm resistor) in the grid circuit is open. A temporary fix is to create a coil of 10 turns of #24 wire around a pe...
Tue, 8 Oct, 2019 at 1:21 PM
Why don't the buttons on the front panel of the FM 100C Exciter stay selected?
If the button does not stay selected unless it is held, the problem is most likely associated with the C53 and C55 capacitors in the power supply section of...
Tue, 8 Oct, 2019 at 2:04 PM
Why don't the buttons on the front panel of the FM 250C Exciter stay selected?
If the button does not stay selected unless it is held, the problem is most likely associated with the C53 and C55 capacitors in the power supply section of...
Tue, 8 Oct, 2019 at 2:05 PM
Why don’t I get the TX ON/OFF or POWER SET menu on my STXe Exciter?
The factory DB-37 Factory Stub connector is not connected/fully inserted on the BE INTERFACE connector on the back, you will only get the following menus wh...
Tue, 8 Oct, 2019 at 2:07 PM
Why have I lost power control in my FMi series transmitter?
Most likely the power control is not within the normal operating range or the Exciter APC is turned OFF. Please review our "FXi 60/250 Maximum Scale Fa...
Tue, 8 Oct, 2019 at 2:18 PM
Why is the filament Voltage on my FM-T or FMi-T TX reading about 1/2 its normal value?
The 18uF capacitor on the filament Voltage regulator is defective. Contact the BE Parts Department and order part number 047-1805.
Tue, 8 Oct, 2019 at 2:19 PM
Why is the High Voltage on my single phase FM 10T/S higher than normal?
The most likely cause is that C2 or C3 across L3 in the HV cabinet has become defective. The resonate HV power supply is not resonating at 50 or 60 Hertz (d...
Tue, 8 Oct, 2019 at 2:21 PM
Why is the output power of my FM 100C pegged and/or maxed out at 125 Watts?
The most likely cause is that the Q401 & Q402 pass transistors (p/n 219-3000) on the RF Amp asssembly are defective.
Tue, 8 Oct, 2019 at 2:22 PM