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 Post subject: Yaesu FT-900
PostPosted: Jul Wed 17, 2019 7:40 am 

Joined: Jan Thu 01, 1970 1:00 am
Posts: 291
Location: Mobile, AL USA
Hello everyone.

This FT-900 transceiver indicates functions (display, modes, etc) but has no audio output nor does it appear to be receiving signals. 

If PTT on mic is pressed, or MOX button depressed, indications are full transmitter output with high (full scale) SWR, with no actual RF output. Transceiver was in standby mode, after I had just used it.

Another thing: the I bought it from says the 9 volt battery (attached) is needed to provide bias to the PA. I still don't understand why this is necessary.
Please help me figure it out.
Reggie N5NJR

 Post subject: Re: Yaesu FT-900
PostPosted: Jul Wed 17, 2019 2:51 pm 
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Joined: Jun Sun 19, 2011 2:31 pm
Posts: 7998
Check the squelch setting (should be fully CCW) and make sure that the led annunciators for the attenuator and IPO (intercept point optimization) are not illuminated.

Did it work before it went into standby? Does your unit have the antenna tuner installed? Try turning tuner off (if equipped) and use a good dummy load to test. Possibly there has been a relay failure in the T/R path.

A stock FT-900 does NOT need any bias battery attached and it sounds like your unit has been modified. Is the battery being fed into the ALC port to reduce transmitter gain? Something is definitely not right with having a battery added and whatever modifications were made could be the root cause of the issues you have experienced.

The technical manual should be available on the Fox Tango website for download and I suspect you are going to be spending some quality time with that manual undoing whatever was done to the FT-900 before you got it.

Rodger WQ9E

 Post subject: Re: Yaesu FT-900
PostPosted: Sep Thu 16, 2021 3:18 pm 

Joined: Feb Tue 07, 2017 3:44 pm
Posts: 36
Location: Bellaire, Ohio 43906
I seen that this thread is a bit old but didn't see a resolution to the question.

My two cents for a couple of things to check. Try rsingl's method first.

I've seen the "Phones" port in the lower left corner of the radio face plate have problems of loosing connection. The port pin connections to the pc are not very robust. The solder joints break. Try inserting your headphones or ext speaker and slightly wiggle it around while listening for any sound. If your do get sound doing this method, the solder joints are bad. If not, the speaker may be bad/dead. Of course, there other things that can create the problem you have. Lots of luck.

"Shoot for the Moon!"...Even if you miss, you'll still land in the STARS.

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