Bob -
That is probably a retrofit caused by failure of the earlier "soupcan"
filter. The soupcan was still in use in the early TR-4s up through
approximately s/n _18000_ , when the "single hermetically sealed can"
filter was used. The shift to "dual, 8-pole filters" started around
s/n 23000.
Unfortunately, the single can filter is still a four pole filter
according to my information, with the resultant poorer carrier and low
frequency sideband suppression.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line & TR-4/C Service Supplement CDs
<www.k4oah.com>
Bob Loving wrote:
Did the TR-3 always use a Drake design (and manufactured) twin
crystal filters unit? From what I can gather from this forum, the
design was a 4-pole design. Is that true?
The unit I have, serial number 12324A, has a filter unit manufactured
by C-F Networks of Phoenix, AZ. The terminating resistors across T6
and T13 are 470-Ohm (instead of the 2.2k shown on the TR-3
schematic), which is identical to the TR-4 series except the two
filters are in a single shield can. Is it possible this is either
6-pole or 8-pole design?
Thank you.
73,
Bob K9JU
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