>Hi everybody:
>
>After both CQWW´s, SSB and CW; my old 922 (16 years) it´s so tired. I have
>some problems with the T2 (see photos); it´s ok the Ip and Hv but the relay
>don´t works and it´s smells bad (like a toaster). I need to know the
>reference of this transformer to replace it, but haven´t the reference. Can
>anybody helps me?.
T2 is usually destroyed by a tube that shorts from the grid to the
filament/cathode. When a short occurs, the +110VDC relay power supply
shorts to ground and the unfused transformer becomes toast during RX
unless the 922 is quickly switched OFF.
The grid-filament short is apparently caused by a surge in grid current
when the TL-922 intermittently oscillates at c. 120MHz. (photo of shorted
3-500Z on p.15 of Sept., 1990 *QST*, "Parasitics Revisited"). // To fix
such an amplifier, the toasted transformer and the shorted tube must be
replaced. (the shorted tube is usually the one with the damaged grid
RF-choke). To prevent a repeat of the same problem, lower-Q VHF
parasitic suppressors can be installed. All of these problems also apply
to the SB-220 - which Kenwood-san seemingly copied. An article on
Circuit Improvements for the Heath SB-220 appears on my Web site.
>
>Thank´s in advance, and I´m waiting for Santa, with a new amplifier.
>
Currently built amplifiers are not without some of the same problems, so
better ask Santa to bring you a soldering-iron.
have fun, Pedro
>73 DX de Pedro, EA 4 KD
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- Rich..., 805.386.3734, www.vcnet.com/measures.
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