[Yaesu] Intermittent deaf receiver/no RF out FT-890AT

[Dr. Gerald N. Johnson]

Look for things common to transmit and receive only on SSB. The first 
thing that comes to mind is the BFO used for carrier on transmit and for 
BFO to the product detector on receive, not used on FM or AM. Then there 
may be another whole IF used only on SSB, not on FM or AM with greater 
selectivity and its mixer and oscillator. Could also be the SSB crystal 
or mechanical filter and its connections.

Having isolated it to a particular area acquire a can of electronic 
circuit coolant (sometimes called freeze mist) and an electric hair 
dryer. With the rig working heat that part of the radio to see if it 
quits with heat. Then cool it to see if it recovers cooled, then heat 
only half that area and if it triggers the fault, cool that half, 
continue cutting the portion of the radio heat cycled until you are down 
to the part. It can be a cable connection (DeoxIT is your pal there), a 
solder connection or a failure inside a part.

73, Jerry, K0CQ

On 8/2/2011 12:33 PM, Bill Lovell wrote:
> At wit's end with this.
>
> The FT-890AT will be cruising along, then suddenly the receiver will go deaf and the rig will not transmit. Just when I think it's a "permanent" condition --- permanent enough to send off for service -- the thing will spring back to life and works perfectly...and sometimes wait a few days before it happens again.
>
> When "dead" it does receive on broadcast band AM, and receives and transmits fine on FM. But SSB and CW, nada.
>
> Anybody ever have this happen and find a solution?
>
> 73,
> Bill. K7JBQ
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