genadiz wrote in
:

On Oct 11, 8:15*am, clifford wright
wrote:
Good day! Has anyone got any application information for the Toyocom
45E2B2 45 MHz 4 pole filter. It comes as 2x3 lead crystal cans.
Unfortunately it has been over 20 years since I started this reciever
project. (It was put to one side after a HEAP of sythesiser problems)
Of course I cannot now find any data on how the two crystal units are
cou
pled
together.
What info I has gives a Zi/o of 4K Ohms and 0.8 pF but the only info on
coupling the 2 is an unexplained figure of 1pF?
That seems too small to me even at 45 MHz!
So what I need urgently is an clarification of the coupling required
betw
een
the 2 units.
Has any kind person got this info anywhere? Or does anyone have circuit
information on a receiver which used this filter? That would give me a
lo
t of
clues.
73's Clifford Wright ZL1BDA ex G3NIA Helensville New Zealand.

Hello.
Your filter is now a discontinued product and placed at
http://www.epsontoyocom.co.jp/englis...on_filter.html

As usual, negative capacitance mean tuned resonant tank, slightly
distuned from 45 MHz.
If you can not measure shape of passband characteristics, simply
ignore these -1 pF.

If you interested, can see on my upconv receievers at
http://www.cqham.ru/forum/showthread.php?t=9688


Thanks Genadiz.
I am an "old timer" and still trying to keep up with new technology at 71
years, after 60 years of electronics!!! A close inspection of your boards
appears to show that there is simply a low value preset capacitor from the
junction of the 2 Xtal units to ground. Is that correct?
I have tried the offset 45 MHz tuned circuit, but it is quite possible
that I had the LC ratio wrong. Perhaps I should aim for a ~4K Ohm
reactance? Unfortunately I don't read Cyrillic. My language skills are
mostly in French, German and Maori with a bit of Swedish and about 20
words of Russian. In any event the only real problem now is the coupling
of the 2 filter units as in your older designs. Matching to the input and
output of the filter is no great problem. 73's Cliff Wright