thanks to Bill Tippett W4ZV and George Cutsogeorge W2VJN for all their efforts
Bill W4ZV arranged with George W2VJN at Inrad to produce a 600hz 4-pole roofing filter kit for the Ten-Tec Orion. The intent was
for this filter to replace the stock 1Khz filter and perhaps obviate the need for the 500hz optional roofing filter. The original kits
were supplied with SMD chip caps but I purchased ceramic disc caps from Mouser as suggested on Bill's Web page,
which everyone should read. In retrospect, this was an excellent decision and I encourage anyone who hasn't worked with surface mount components to do likewise.
Here is an account of my construction:
solder wires to adapter board - green ground wires were eventually stripped bare
snip the Radio Shack 276-150 proto board down to size; we'll use the bottom piece
the solid horizontal trace is the ground buss; install the capacitors starting from the right (input) side:
leave one column blank for input connection
connect 47pf+15pf paralleled from gnd buss to lower hole in 2nd column (col2); both cap leads will fit in a single hole
xtal#1 (red) will go in col2 and col4 (don't install yet, just capacitors now); connect 100pf+100pf from gnd to col4
xtal#2 (blue) will go in col6 and col8; connect 100pf+100pf from gnd to col8
xtal#3 will go in col10 and col12; connect 100pf+100pf from gnd to col12
xtal#4 (green) will go in col14 and col16; connect 47pf+15pf from gnd to col16
lightly tin center of each xtal; tin the end of a 2-inch length of bare wire; solder the wire to the xtal
insert the xtals into the holes indicated above after shaping the ground wire to fit into a ground buss hole
solder the xtals in place from right to left after bridging connections between each pair of xtals - I just
used the xtal leads
trim the board with small diagonal cutting pliers, leaving one column on each end for connection
bend the bare ground connecting wires and insert them into the end ground buss holes on the filter board as
shown in the photo. The width of the filter board is practically a perfect fit!
push the filter board snug, as far as it will go and solder the ground wires
measure the length of in/out wires needed, strip, insert into a hole on end columns, make electrical
connection on the solder side to col2 and col16 and solder
You're done!!! The filter board should be held firmly in place on the adapter board by the
electrical connections. Remove the Orion's top cover and filter cover, remove the 1Khz roofing
filter and insert the new 600hz filter.
CW audio passband spectra (400hz center) of roofing filters with DSP selectivity opened to 2Khz:
1.8Khz T-T #218 violet
600hz Inrad #352 turqoise
500hz T-T #217 yellow
250hz T-T #219 green
The 352 filter passband looks excellent!