Yaesu: Yaesu FT-8800 Receive Deaf?

[KA0XR]

I have a Yaesu FT-8800 that recently seems to have become increasingly deaf. The radio is 14 years old and I never had any issues until now. It's been in a stable environment first as a base and then as a mobile but with little banging around. When using the same antenna/coax/position it could not pull in NOAA Weather signals that my Yaesu FT-70dr could easily pull in. Same poor receive performance observed on various 2 meter frequencies in comparison. I haven't changed any menu items or other parameters that might be attenuating received signals.

Another possibly related issue is that the power output on high on 2m is only ~32 watts (antenna SWR around 1.2) which makes me wonder if multiple issues are going on. Any insight on this would be much appreciated!

 

[MTS2000des]

There is a known issue with IF filter "rot" from mid/late 2000s Japanese radios. The IF filters die and poor receive sensitivity is usually the result. If a full alignment won't help, that's where I'd start looking. The radio is still supported by Yaesu worst comes to worst if you don't feel like tackling the job yourself.

 

[cmdrwill]

Another common problem is the little transistor that amplifies the receive signals IS bad.
Why? High SWR on transmit will 'bun up' the little transistor.

AKA 'smoked front end'.

 

[KA0XR]

Another common problem is the little transistor that amplifies the receive signals IS bad.
Why? High SWR on transmit will 'bun up' the little transistor.

AKA 'smoked front end'.

Would a degraded front end explain why the radio is now down to only ~32 watts output on high power (with only a fraction of a watt reflected when measured on my Bird 43 meter) instead of the specified 50 watts?

I've never used crappy or sketchy antennas with this radio, either commercial grade Maxrad or Laird quarter waves for 2m (3/4 wave for 70cm) or the Larsen NMO 2m/70cm dual band antenna.

 

[AK9R]

Have you checked the power supply voltage at the radio? It should be in spec to produce full rated power. Are you transmitting through the Bird into a dummy load?

 

[KA0XR]

Have you checked the power supply voltage at the radio? It should be in spec to produce full rated power. Are you transmitting through the Bird into a dummy load?

I hooked the radio up to a 39 amp power supply that has a volt/amp readout and into a 2m base antenna (Diamond CP22e) through the Bird (50 watt slug). I don't have a dummy load but this is the best I could do. Previous test was done in its mobile location - 12v car battery to a 1/4 wave mag mount antenna.

On high power I measured 43.5 watts out and around 1 watt reflected. Power meter read a steady 13.7 volts with current draw of 6.7 amps. Based on the manual this should have been 8.5 amps, so maybe the final output transistors are a bit worn but by no means shot. I tried 2 different simplex frequencies to see if there were any differences based on antenna SWR but results were similar.

The radio was still pretty deaf despite being hooked up to a much higher gain and elevated antenna. It could barely pick up a regional NOAA transmitter that is usually easy to hear using a typical HT portable setup at ground level with a good aftermarket antenna.

 

[MTS2000des]

Sure sounds like front end filters are shot. Power output drop is typical for a radio that is 15 years old that's had a fair amount of use, but an alignment may also bring it back up to par.