The tunnel diode based 7B92A is serial number B069999 and below.
Physically if you look inside at the two trigger circuit boards, the
ones with tunnel diodes have 3 DIP packages in a row while the newer
ones without tunnel diodes have a DIP package next to an X shaped IC
or hybrid mount.
On Tue, 17 Jul 2012 09:09:01 -0700, Richard Solomon
<dickw1ksz@...> wrote:
I have a few 7B92's here. How do I tell which ones have TD's in them. Is
there
a particular place on the board to look for them ?
Tnx, Dick, W1KSZ
On Mon, Jul 16, 2012 at 2:15 PM, Albert <aodiversen@...> wrote:
**
Hi Raymond,
Tried a tunnel diode based 7B92 in a 7904A/7A29, with input from a TG501
and internal triggering. At 2 ns and 1 ns the TG501 "pulse" stream is
nearly a sine wave. At 2 ns (500 MHz) the 7B92 triggers well in Norm mode
with signal less than 0.5 div. At 1 ns (1 GHz) it fails in Norm mode but
syncs in HF Sync mode (and signal far below 0.5 div). But a 7B15 performed
far better with a much sharper trace, so with much less jitter. Even at 1
GHz the 7B15 would trigger in Norm mode.
Checking TB performance this way in a 7904(A) is somewhat undefined since
it's not clear what trigger amplitude arrives at the TB. Testing in a 7104
would give better information.
The 7B92 was "as is", so other units might perform better.
Albert
Tried my newly acquired SG504 (with leveling head) and saw this 7B92A
triggering happily at around 1.05 GHz on my 7904 + 7A19... Of course,
amplitude isn't shown anywhere near correctly. 7B92A is specified to
trigger "above 500MHz".
Raymond
David Hess