EMRFD Message Archive 8711

Message	Date	From	Subject
8711	2013-06-07 22:38:33	n5emqrp	W7ZOI Spectrum Analyzer - 100 mhz Crystal
I'm trying to make sure I understand some basics. (Finally started working on my SA (decades in the making). I have two glass encased 100.671 mhz crystals (HC-6) I could use. To use one of these in the 2nd Mixer/2nd LO board, would require that the VCO tune 671 khz above the design 110 - 180 mhz. Likewise, the modification to 10.7 Mz IF requires the LO tune 700 khz up. To use this crystal and change 2nd IF would require that the VCO be 1.371 mHz up (111.371 - 181.371 mHz). The POS-200+ data sheet says Vtune 3+ v to abt 13 v for this span. Will the timebase do that? Did I do all that math correctly? (Looks like the 110 Mhz filter will probably tune to 111.371) I also have a low Phase Noise Oscillator at 100 mhz to use (-130 dBc/hz at 1Khz - Miliren 210 OCXO), but would prefer a crystal LO. Thanks. Ed, N5EM
8714	2013-06-08 12:54:50	Wes	Re: W7ZOI Spectrum Analyzer - 100 mhz Crystal
Hi Ed, You should have no problems with the slightly different crystal. The POS200 will tune the extra range. A different crystal will be required if you do the TG, but the easy way to get a TG is with the design done by k3nhi and k5irk, which is on my web site. I think it's also
8715	2013-06-08 14:46:55	John Lawson	Re: W7ZOI Spectrum Analyzer - 100 mhz Crystal
Hi Ed, I see that Wes has responded to your email so you are good to go. I'm including this only if you want to get that Crystal Frequency closer to 100 MHz for a warm feeling in building your SA and perhaps easier duplication/modification of that 110 MHz filter in the SA. Surplus Sales of Nebraska sells the following crystals listed in their 70 MHz and up category: 99.86670 MHz and 100.0667MHz. If I recall correctly they have a $15 minimum order quantity. However not for sure how their crystals might stack up to those crystals you have. Hope this might be of help to you. Best of luck, John K5IRK n5emqrp <n5emqrp@gmail.com> wrote: >I'm trying to make sure I understand some basics. (Finally started working on my SA (decades in the making). > >I have two glass encased 100.671 mhz crystals (HC-6) I could use. To use one of these in the 2nd Mixer/2nd LO board, would require that the VCO tune 671 khz above the design 110 - 180 mhz. Likewise, the modification to 10.7 Mz IF requires the LO tune 700 khz up. To use this crystal and change 2nd IF would require that the VCO be 1.371 mHz up (111.371 - 181.371 mHz). The POS-200+ data sheet says Vtune 3+ v to abt 13 v for this span. Will the timebase do that? Did I do all that math correctly? (Looks like the 110 Mhz filter will probably tune to 111.371) > >I also have a low Phase Noise Oscillator at 100 mhz to use (-130 dBc/hz at 1Khz - Miliren 210 OCXO), but would prefer a crystal LO. Thanks. > >Ed, N5EM > [Non-text portions of this message have been removed]