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Title: SX-99 schematic Post by: N8IE on February 02, 2009, 09:17:29 AM Good morning all,
My beloved SX-99 has fell ill. :'( I suspect something in the BFO circuit has gone bad, when switched between AM\CW no changes are present and only the strongest of signals are present. I have noticed for a while, a light "pop" when the radio was first turned on, could be a bad filter cap? Anyway, I have a copy of the schematic but not one showing voltages, is there such an animal around somewhere? Thanks es 73 Dan, N8IE Title: Re: SX-99 schematic Post by: W3FJJ on February 02, 2009, 09:30:01 AM Not sure if the voltages are in the owners manual, but
BAMA has the manual you can download. http://bama.sbc.edu/hallicra.htm GL CHuck Title: Re: SX-99 schematic Post by: N8IE on February 02, 2009, 12:12:52 PM Not sure if the voltages are in the owners manual, but BAMA has the manual you can download. http://bama.sbc.edu/hallicra.htm GL CHuck Thanks Chuck, I guess this is a case of RTFM. :-[ I have that manual but failed to take a closer look at page 10, you know the one labeled "Voltage Chart". D'ohhhhhhhh. 73 Dan, N8IE Title: Re: SX-99 schematic Post by: N8IE on February 02, 2009, 08:13:44 PM Well, a little time with the schematic and the problem is fixed.
A wire between V4 and V5 came loose. After going over the radio I see that I need to replace a few resistors in there! One has me stumped though, it appears to read as a 100,000 Ohm and is a carbon type. The schematic only shows two such resistors and both are 1/2 watt, this puppy is at least 1 inch in diameter. It connects at pin 4 of T3 and grounds out on V7. 73 Dan, N8IE Title: Re: SX-99 schematic Post by: N8IE on February 03, 2009, 07:16:03 AM Thanks to the Hallicrafters group, I now know the component in question is a "black beauty" capacitor. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Wow, amazing how much one learns..... now I have a headache! ;D 73 Dan, N8IE |