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legg legg is offline
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Default Harman Kardon FM100 - early version?

On Mon, 30 Jul 2012 13:01:32 -0500, legg wrote:


1) V1 dual triode in the RF amp and mixer stage are the older
6AQ8/ECC81, rather than the later 6BK7A/ECC83 expected in the SAM's
schematic and listed in other web references.


Should read 6AQ8/ECC85 and 6BK7A/ECC81

2) V2 dual triode in the AFC and oscillator sections is 6AQ8/ECC81
rather than the 12AT7 expected in the SAM's schematic and web
references.


Again 6AQ8/ECC85

As well, first IF is 6AU6, vs the 6BA6 in the documentation. Didn't
figure that this was major, because the other two IFs are 6BA6, as
indicated in SAM's and no problems appear in this section.

One oddity. Swapping the 2nd and 3rd IF tubes result in either large
DC values at the multiplex output (~3V), or normal values (100mV),
indicating a part-dependent instability. They both test with similar
u.

RL