Does part of the K3 spec mention that it's supposed to be a precision swr indicator? If so, I missed that. I thought that I was merely getting an outstanding transceiver, especially for cw, at a relatively low cost.
This year, I became active on ham radio after a multi-decade hiatus. Before I left, the normal assumption about swr meters with diodes was that they had reduced accuracy at low power levels because of diode non-linearities. Has this changed while I was away? 73, Dunc, W5DC Wayne Burdick wrote: > There's no way to avoid some increase in SWR reading error at low > power, since the bridge transformers have a low coupling ratio to > avoid heating at full power. We're already using very low-drop diodes > and pre-biasing them. > > That said, I am going to look at a correction based on power level if > possible. > > tnx > Wayne > N6KR > > On Nov 9, 2009, at 9:06 AM, Jack Smith wrote: > > >> Wayne: >> >> There's also an SWR versus output power issue, or is that part of >> the first correction factor? The SWR error increases significantly >> at lower power. I have not had a chance to plot the data because it >> was not part of the original question, but there is a clear power >> related error seen in the raw data, which I assume is tied to the >> detector diode linearity at low voltages. >> >> Jack K8ZOA >> >> >> Wayne Burdick wrote: >> >>> There are two sources of the reported SWR inaccuracies: >>> >>> - An SWR calculation scalar that I'll be adjusting in firmware; >>> this is what's causing a 2:1 SWR to read closer to 1.8:1 on some >>> K3s. >>> >>> - The KAT3 itself, and to a much lesser degree, the KANT3, which >>> is present if the ATU is not installed. Both modules have inherent >>> stray reactance, part of which is due to the 8.2 MHz first-IF >>> trap. These strays slightly alter the impedance seen by the K3's >>> SWR bridge. >>> >>> Even when the scalar correction is applied, there will still be a >>> small frequency-dependent variation in SWR reading between the >>> K3's bridge and an external instrument. This has no impact on K3 >>> operation. >>> >>> 73, >>> Wayne >>> N6KR >>> >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:[email protected] >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> >>> >>> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
