<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue-Light, Helvetica Neue Light, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:8pt"><div><span>Some people do use RG58/U cables for the interconnection. However, that often requires retuning of the equipment as well as, sometimes, not enough injection, especially from the heterodyne oscillator into the transmitter.</span></div><div style="color: rgb(0, 0, 0); font-size: 11px; font-family: HelveticaNeue-Light, 'Helvetica Neue Light', 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 11px; font-family: HelveticaNeue-Light, 'Helvetica Neue Light', 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>It is the capacity of the interconnect cables
that affect the tuning of the circuits.</span></div><div style="color: rgb(0, 0, 0); font-size: 11px; font-family: HelveticaNeue-Light, 'Helvetica Neue Light', 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 11px; font-family: HelveticaNeue-Light, 'Helvetica Neue Light', 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>If additional circuitry was used in the receivers (SB-300, SB-301, and SB-303), then the price of the kit would have to be increased. Heath furnished the RG62/U cable in the receiver kit. Therefore, amateur radio operators did not have to obtain cable. Remember, Heath had no idea that the SB-30X receivers were going to be used over 40-years later and, as such, they didn't even consider using RG58/U
cables.</span></div><div style="color: rgb(0, 0, 0); font-size: 11px; font-family: HelveticaNeue-Light, 'Helvetica Neue Light', 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span><br></span></div><div style="color: rgb(0, 0, 0); font-size: 11px; font-family: HelveticaNeue-Light, 'Helvetica Neue Light', 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-style: normal; background-color: transparent;"><span>Using RG59/U cable for the interconnect cables does result in less capacitance for the assemblies and, sometimes, that works OK on the 10-meter band. But, for best operation, use the 24-inch RG62/U cables.</span></div><div></div><div> </div><div>Glen, K9STH
<br>
<br>Website: http://k9sth.net</div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: HelveticaNeue-Light, 'Helvetica Neue Light', 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 8pt;"> <div style="font-family: HelveticaNeue, 'Helvetica Neue', Helvetica, Arial, 'Lucida Grande', sans-serif; font-size: 12pt;"> <div dir="ltr"> <font size="2" face="Arial"> On Monday, August 18, 2014 2:25 PM, Robert Myers <rsmyers@rogers.com> wrote:<br> </font> </div> <br><br> <div class="y_msg_container">Question about the SB-303 / SB-401 interconnection cables *required* for the<br>HFO, BFO and LMO.<br><br>As I am sure most are aware, the SB-303 and SB-401 manuals call for the<br>following cables to be connected between the various SB-303 oscillator<br>output sockets and the corresponding SB-401 oscillator input sockets:<br><br>SB-303 ‘BFO OUT’ -> 24”
RG-62/U -> SB-401 ‘RCVR BFO’<br>SB-303 ‘HFO OUT’ -> 24” RG-62/U -> SB-401 ‘HET OSC’<br>SB-303 ‘LMO OUT’ -> 24” RG-174/U -> SB-401 ‘RCVR LMO’<br><br>It seems to me that the designers, for some reason, decided to incorporate<br>the various cable capacitances (that result from their specified lengths)<br>and their characteristic impedances, along with the input impedances of<br>those various oscillator inputs of the SB-401, into what amounts to<br>‘essential operating circuitry’ of the corresponding oscillators based on<br>the SB-303. (But why? To save money?)<br><br>Is the requirement for 'cable weirdness' due to the various oscillators’<br>output circuitry within the ‘303, or is it due to the requirements of<br>various oscillators’ input circuitry within the ‘401? Or is it a<br>combination of both?<br><br>I mean, if the ‘303 requires a particular capacitance ‘hanging
off’ the<br>LMO’s output socket (such being provided by exactly 24 inches of RG-174/U)<br>in order to function properly, as well as a 50 Ohm load (inside the 401<br>during transceiver), would it not have been better to do something like<br>provide all those necessities *within* the ‘303 (right at the LMO<br>oscillator) and follow that by an isolating buffer/voltage-follower (still<br>inside the ‘303) with a 50 Ohm output impedance? You could do the same for<br>the HET, and BFO oscillators’ circuitry as well – thus allowing for<br>arbitrary lengths of, say, RG-58/U cables (not different cables) for<br>interconnection of the HET, LMO, and BFO sockets between the two units.<br><br>Is there a fix for this cable 'weirdness,' allowing the cables to be the<br>same type (say, 50 Ohm RG-58 since you need that for the antenna<br>connections, for sure), and their lengths to be not critical?<br><br>Thanks,<br>Rob Myers,
VE3JQL<br><br><br><br><br><br><br><br>______________________________________________________________<br>Heathkit mailing list<br>Home: <a href="http://mailman.qth.net/mailman/listinfo/heathkit" target="_blank">http://mailman.qth.net/mailman/listinfo/heathkit</a><br>Help: <a href="http://mailman.qth.net/mmfaq.htm" target="_blank">http://mailman.qth.net/mmfaq.htm</a><br>Post: mailto:<a ymailto="mailto:Heathkit@mailman.qth.net" href="mailto:Heathkit@mailman.qth.net">Heathkit@mailman.qth.net</a><br><br>List Administrator: Duane Fischer, W8DBF<br>** For Assistance: dfischer at usol.com **<br><br><br>This list hosted by: <a href="http://www.qsl.net/" target="_blank">http://www.qsl.net</a><br>Please help support this email list: <a href="http://www.qsl.net/donate.html" target="_blank">http://www.qsl.net/donate.html</a><br><br></div> </div> </div> </div> </div></body></html>