Message	Date	From	Subject
2013	2008-09-06 11:22:34	bkopski	PISTON CAPACITOR FOLLOWUP
Hi Ray, et al, The previously posted subject was a preliminary look at an individual resonator at about 400 mHz to determine a suitable tuning method / device. The HB piston cap proved quite satisfactory and this allowed completion of the real goal: a triple tuned fairly narrow 400 mHz filter. Two newly posted photos (see K3NHI folder) show the inside and outside of the completed filter, and a third photo shows the measured performance. This latter photo does contain a small error in that the (violet) system reference trace is actually about 2 dB higher than shown (test error) so the IL is really about 5 6 dB as best I can determine. While the assembly shown does perform as shown, were I to do it again I'd build an enclosure entirely of pc board in the interest of better physical stability and lower internal leakage / section-to-section coupling. The RCA connectors shown here pressed into duty well past the audio domain - are all I have to work with but do seem to work satisfactorily for my purposes. The inductors are #12 "house wire" and ½" id. Cordially and 73, Bob K3NHI
2015	2008-09-06 16:04:42	Allison Parent	Re: PISTON CAPACITOR FOLLOWUP

2017	2008-09-07 06:57:09	bkopski	Re: PISTON CAPACITOR FOLLOWUP
Hi Allison, et al,
2018	2008-09-07 07:15:11	Allison Parent	Re: PISTON CAPACITOR FOLLOWUP

2019	2008-09-07 08:46:17	bobtbobbo	Re: PISTON CAPACITOR FOLLOWUP

2020	2008-09-07 09:50:19	bkopski	Re: PISTON CAPACITOR FOLLOWUP
OK, BUT - Bob, one needs to be CAREFUL in choosing RCA connectors because not all RCA connectors are created equal. It seems various mfgrs take some liberty with dimensions and I have experienced mfgr combinations that could not be mated ('way tight) and combos that simply slipped apart ('way loose). Having learned this the hard way, I've settled
2021	2008-09-07 12:16:52	Allison Parent	Re: PISTON CAPACITOR FOLLOWUP

2022	2008-09-07 15:38:30	bobtbobbo	Re: PISTON CAPACITOR FOLLOWUP

2030	2008-09-08 03:53:19	timshoppa	Re: PISTON CAPACITOR FOLLOWUP

Hi Ray, et al,

The previously posted subject was a preliminary look at an individual
resonator at about 400 mHz to determine a suitable tuning method /
device. The HB piston cap proved quite satisfactory and this allowed
completion of the real goal: a triple tuned fairly narrow 400 mHz
filter.

Two newly posted photos (see K3NHI folder) show the inside and
outside of the completed filter, and a third photo shows the measured
performance. This latter photo does contain a small error in that
the (violet) system reference trace is actually about 2 dB higher
than shown (test error) so the IL is really about 5 6 dB as best
I can determine.

While the assembly shown does perform as shown, were I to do it again
I'd build an enclosure entirely of pc board in the interest of better
physical stability and lower internal leakage / section-to-section
coupling. The RCA connectors shown here pressed into duty well
past the audio domain - are all I have to work with but do seem to
work satisfactorily for my purposes. The inductors are #12 "house
wire" and ½" id.

Cordially and 73,

Bob K3NHI