tag:blogger.com,1999:blog-7590176649168185428.post1419932144300798823..comments2024-03-28T08:01:27.111-04:00Comments on SolderSmoke Daily News: 11 MHz IF for new BITX 20/40 Dual Bander? Also: Cabinetry and Socketry Bill Mearahttp://www.blogger.com/profile/07662500663603350847noreply@blogger.comBlogger10125tag:blogger.com,1999:blog-7590176649168185428.post-87858686725863562232013-12-05T10:02:27.793-05:002013-12-05T10:02:27.793-05:00Spur Calculators:
Hittite Microwave has a powerfu...Spur Calculators:<br /><br />Hittite Microwave has a powerful online spurious calculator. From their homepage [hittite(dot)com] look under Engineering Tools. Be sure to enable Java in your browser. Also click the Help button in the calculator and from the Help pop-up page click to watch the 8-minute tutorial.<br /><br />In the Hittite tool it is not apparent, but you can click the units under the entry boxes and select KHz, MHz, GHz, etc.<br /><br />A couple of free RF tools downloadable (free) programs have spurious calculators:<br /><br />RFSim99 (Dated but OK)<br /><br />AppCAD (HP/Agilent)<br /><br />Google knows where to find these programs.<br /><br />The Microwaves101(dot)com site has a downloadable Excel Spurious Calculator spreadsheet. Nice, lots of help embedded in the spreadsheet. It works in MSOffice 2000 so it should work in LibreOffice/OpenOffce as well.<br /><br />leleivre(dot)com/rf_mixerspur(dot)html this is a simple online spur calculator, have a look at the other RF Tools available while you're there.<br /><br />I'm sure there are more spur calculators/simulators out there (anyone else?)<br /><br />Best 73's, David WB4ONA<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-52384063737592700272013-12-04T05:24:12.570-05:002013-12-04T05:24:12.570-05:00Thanks for all the comments.
Re the DDS. As Farh...Thanks for all the comments. <br />Re the DDS. As Farhan has said, this is kind of a religious thing for me. I have to keep everything analog, discrete, HDR.<br />On the 10.7 Mhz rocks, I think I saw some on Mouser or Digikey. Maybe 10.73 (!) but for 20/40 the harmonics from the VFO would be bad birdies. <br />On diode switching... Good idea Alan and Juanjo!<br />Henk -- thanks for the IF freq paper. 73 to all Bill Mearahttps://www.blogger.com/profile/07662500663603350847noreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-26527720523373192852013-12-03T14:46:55.849-05:002013-12-03T14:46:55.849-05:00The idea of getting crystals from 10.7MHz filters ...The idea of getting crystals from 10.7MHz filters is interesting, but is it practical?<br /><br />I've never taken a crystal filter apart, but what's inside? In the fifties there were articles about modifying Motorola Permakay filters, but the first step was to get rid of the epoxy or whatever that filled the can. And if the 10.7MHz filters are recent enough, are they likely to have crystals in holders inside? <br /><br />For that matter, I have assumed that if a filter is old enough to use standalone crystals, then the circuit would not be a ladder filter (ie crystals on the same frequency) but sets of crystals spaced enough apart to provide the bandwidth. So if it's a simple filter, you'd get only a few crystals on the same frequency, if that.<br /><br />Considering it is a common IF frequency, one might think 10.7Mhz crystals had become commodity crystals, but when I've looked, they haven't been part of the off the shelf selection.<br /><br />10.240MHz is common, converting 10.7MHz to 455KHz, and also common in synthesizers in CB sets. Older cordless phones used them a lot, though by now the older cordless phones seem to have disappeared from the garage sales. I'm not doing the math to see if 10.240MHz would be useful.<br /><br />I thought I'd found something really great a few months ago, an SSB CB set. I've long thought that sort of thing would be useful, if found cheap, and this one was only five dollars. But it seems that after a certain point, the filters were not so great, so they are relatively wide filters, used for AM and SSB. Probably still useful for VHF worked (or just run the CB set into a transverter), but not a useful source of 10.7MHz SSB filters like I'd originally thought.<br /><br /> Michael VE2BVW<br />Michael Blacknoreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-60414770075769215592013-12-02T11:25:40.351-05:002013-12-02T11:25:40.351-05:00Dear Bill,
Why don't you get really fancy and...Dear Bill,<br /><br />Why don't you get really fancy and not worry about switching a VFO and use a DDS for the oscillator with a digital readout?<br /><br />I bet Billy can help you do it with a Ardunio or a PICAXE for a processor. They do work nicely as VFO's and HFO's for Amateur Radio Frequencies and almost as cheap as Crystals. Then Later on if you want to change frequecies, you just change the tuning of the DDS. (Just my humble opinion.<br /><br />73 Dave WA5DJJ in New Mexico.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-83092927987073781782013-12-02T06:40:51.497-05:002013-12-02T06:40:51.497-05:00Hi Bill,
must read:
http://pa0su.nl/PDFiles/Freq...Hi Bill,<br /><br />must read:<br /><br />http://pa0su.nl/PDFiles/Frequencies%20in%20Hetrodynes.pdf<br /><br />best 73<br /><br />Henk/PA0EMEPA0EMEnoreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-82687428345740405532013-12-02T03:31:30.441-05:002013-12-02T03:31:30.441-05:00Hola Bill,
De acuerdo con Alan W2AEW. Iba a suger...Hola Bill,<br /><br />De acuerdo con Alan W2AEW. Iba a sugerirte ahorrarte el relé y usar conmutación con un diodo o un transistor. Por ejemplo, el RIT del Optimized QRP Transceiver (un clásico). Un abrazo, Liam y Felices Fiestas que se aproximan...<br /><br />de Juanjo EC5ACAJuanjo EC5ACAhttps://www.blogger.com/profile/03289029596279413493noreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-13221143398863123512013-12-01T20:58:02.322-05:002013-12-01T20:58:02.322-05:00Here are some vids to help:
Basics of PIN diodes ...Here are some vids to help:<br /><br />Basics of PIN diodes for RF switching:<br />https://www.youtube.com/watch?v=XpYsCM_Wf50<br /><br />and basics of using diodes as switches (general):<br />http://www.youtube.com/watch?v=YBNIq_d56sA<br /><br />Alan<br />w2aewhttps://www.blogger.com/profile/13487833918600029532noreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-19090376245017546392013-12-01T20:55:50.685-05:002013-12-01T20:55:50.685-05:00Hey Bill - how about getting "fancy" and...Hey Bill - how about getting "fancy" and using diodes to switch in the extra capacitance instead of a reed relay.w2aewhttps://www.blogger.com/profile/13487833918600029532noreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-48320178528813197672013-12-01T16:02:05.794-05:002013-12-01T16:02:05.794-05:00I thought about that Peter. In fact, that was the...I thought about that Peter. In fact, that was the solution to the simultaneous equations asking what IF and VFO freq could be used for 40 and 20. But I think those birdies would be fierce it might be better just to switch in some additional reactance to move the VFO freq. Thanks and 73 Bill Bill Mearahttps://www.blogger.com/profile/07662500663603350847noreply@blogger.comtag:blogger.com,1999:blog-7590176649168185428.post-62553271419878852262013-12-01T14:07:37.788-05:002013-12-01T14:07:37.788-05:00Haven't tried this but have you thought of usi...Haven't tried this but have you thought of using a 10.7 MHz IF? Using crystals salvaged from old filters from VHF FM transceivers. A 10.7 MHz IF would allow coverage of two bands with a single 3.3 - 3.7 MHz VFO. There may however be a birdie due to VFO harmonics but the arrangement would remove the need for VFO switching. 73, Peter VK3YEAnonymousnoreply@blogger.com