283	2006-12-31 06:52:43	Hari G	Wide VCO for SA
Message	Date	From	Subject
Hi All, Iam looking for a wide VCO for the SA project, there is mention of using discrete VCO for initial testing.Any references or circuits for the VCO is appreciated. I got hold of SRA-1 mixers think its ok to use that instead of TUF. Happy New Year Best Regards Hari
284	2006-12-31 07:08:12	Lasse	Re: Wide VCO for SA
Har, how wide is "wide"?? And what freq.? To roll your own is perfectly possible, but it would be a lot easier if you have access to RF instruments... if you are more of a beginner why not try one of MiniCircuits ready-made VCO's? Not too expensive and allows you to get the instrument going, and you can then concentrate to roll your own VCO. There was a design in VHF Communication ten years ago regarding wide band VCO's. Sorry but do not have the articles available, maybe someone else?? /Lasse On Sun, 31 Dec 2006 20:03:24 +0530 "Hari G" wrote: > Hi All, > > Iam looking for a wide VCO for the SA project, there is >mention of using > discrete VCO for initial testing.Any references or >circuits for the VCO is > appreciated. > I got hold of SRA-1 mixers think its ok to use that >instead of TUF. > > Happy New Year > > Best Regards > Hari
285	2006-12-31 08:04:47	Hari G	Re: Wide VCO for SA
Lasse, Iam looking for the same spec of POS200 for the ZOI SA, iam in VU and i wanted this to test till i get hold of POS-200 which iam trying locally but no luck so far. Many thanks Hari(VU2GHB) On 12/31/06, Lasse <lasse.moell@swipnet.se> wrote: Har, how wide is "wide"?? And what freq.? To roll your own is perfectly possible, but it would be a lot easier if you have access to RF instruments... if you are more of a beginner why not try one of MiniCircuits ready-made VCO's? Not too expensive and allows you to get the instrument going, and you can then concentrate to roll your own VCO. There was a design in VHF Communication ten years ago regarding wide band VCO's. Sorry but do not have the articles available, maybe someone else?? /Lasse On Sun, 31 Dec 2006 20:03:24 +0530 "Hari G" wrote: > Hi All, > > Iam looking for a wide VCO for the SA project, there is >mention of using > discrete VCO for initial testing.Any references or >circuits for the VCO is > appreciated. > I got hold of SRA-1 mixers think its ok to use that >instead of TUF. > > Happy New Year > > Best Regards > Hari -- De Hari VU2GHB
286	2006-12-31 15:00:01	jr_dakota	Re: Wide VCO for SA
You could easily take this circuit < http://www.hanssummers.com/electronics/equipment/spectrumanalyser/mixer1/index.htm > and modify the range and then use this setup for the 602/612 < http://www.pan-tex.net/usr/r/receivers/svfo.htm#ne602 > to bring the LO signal to the output (IF) port of the 602 which gives you a little more drive for the diode DBM and buffers the VFO (You'll probably need some more gain to get your +7 or +17 LO drive for the DBM) It's a cheap and easy way to make a decent VCO and easy to tweak for the frequency range you want JR
287	2006-12-31 18:43:55	Hari G	Re: Wide VCO for SA
Jr , Thanks , I have 612 with me, i will try with a J310 buffer and then followed by a MARx MMIC and check the range i get. Few more questions, how about the ampliude will that be same for the full range or will it change and need an AGC arrangement ? What need to done with the mixer inputs and outputs, those pins to be left free or ac grounded with caps ?. Happy Newyear to All Many thanks Bes Regards Hari
288	2007-01-01 13:07:40	jr_dakota	Re: Wide VCO for SA
The 2nd link shows you how to set up the inputs to make the 602's LO appear at the output, basically one input is tied to a cap to ground like you would normally for a single ended (unbalanced) input and the remaining input is tied to ground via a 10k ohm resistor As far as amplitude over range I can't say as I've never tested for it at those frequencies ... JR