This last pass of SO-50 , The transponder turned on and I gave my call sign. Thereafter the transponder was intermittent . I heard partial callsigns but for the most part all that was present was the normal noise level. I tried several times to get into the transponder with negative results. I tried several times to turn the transponder on with the pl tone but no luck. This happened during the complete pass of which I had a maximum elevation of 42degrees. Did anyone else experience the same condition ?? Thanks JACK KC7MG