[TenTec] two 4 pole = one 8 pole

[Vin Legare]

Here's my guidlines for reconstructing 2 4 pole filters into an 8 pole.
Hope it helps.

1.  filter A & B = 4 pole filters, 9 Mhz, 2.4 Khz; each has 5 caps: 51, 100,
131, 100 & 51 pf;  you will need to purchase 2 new 100 pf caps (actually 116
pf would be best but the closest value on hand was 100 pf  which should be
fine, 120 would also be OK)
2.  filter A will be used as the "parts" filter
3.  filter B will be the new 8 pole filter (if you have any 8 pole filters,
observe the symmetry and how the crystal case ground wires are connected,
your new 8 pole should be similar)
4.  carefully remove the 4 xtals and 2 100 pf caps from filter A, avoid
excessive heat, use a small soldering iron, 20-40 watts
5.  remove the 2 small wire jumpers from B and also unconnect the 2 xtal
ground wires from the PC board, leave them connected to the xtal cases
6.  look at B, identify the locations for the new xtals and caps, remove
excessive solder from the holes (use a safety pin to pierce the hole as you
heat it - solder won't stick to the pin) 
7.  install the 4 xtals from A onto B, 2 on each side in the correct holes,
all 8 xtals should line up
8.  connect the xtal ground wires to the new xtals on B and add wire to
continue to ground as originally wired 
9.  install the 2 new 116 (or 100) pf caps in place of the 2 existing 51 pf caps
10. install the 2 100 pf caps from A onto B 
11. install the remaining 2 51 pf caps at the input and output of the filter
12. the filter should be complete, 8 xtals and 9 caps: the xtals are
connected in series from input peg to output peg; the caps connect from each
junction 51-100-116-100-131-100-116-100-51
11. check your work ... compare to other existing 8 pole filters) ... done  ;->

     Good luck and regards to all   Vin   W1TUJ


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