Gwyn -
Certainly sounds like a bad filter. Can't say I've ever seen or heard
of one failing that way. Seems highly unlikely.
I'd start by just connecting a wire between the leads going to the input
and output of the filter, after disconnecting them from the filter itself.
The filter is most likely just a series of four (it's a four pole
filter) crystals connected in series with small caps to ground between
them. It's a little hard to imagine THREE crystals all failing or
coming 'unglued' at the same time. I assume this was a catastrophic
failure. Does the receiver still seem about the same sensitivity, just
restricted?
Let us know what you find!
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs
<www.k4oah.com>
Griffiths G. wrote:
Folks
Does anyone have experience of the R4B as-fitted xtal fliter showing a -3dB
bandwidth of just 250Hz, from 5644.910 to 5644.660kHz
This suggests to me that only one crystal is in circuit, but I do not have the
circuit of what is in the can so I can be sure.
Is there a circuit available?
Before I dismantle, suggestions welcome as to any other diagnostics I can do.
many thanks
73s, Gwyn Griffiths
G3ZIL
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