Hi Karl, I think there are a few issues to clear up here.
The K3 uses PIN diodes that are rated down to around 500 kHz, so they won't cause any IMD due to broadcast band signals. Such PIN diodes are readily available, but more expensive, so I can see why a manufacturer might want to use relay switching instead. That wasn't an option in the K3 -- it had to have solid-state T/R switching. In addition to using the right PIN diodes, we took two extra precautions. First, we incorporated a high-pass filter into the T/R switch. It rolls off signals below 1 MHz to ensure that extremely strong signals in the 500 kHz range or below are attenuated. The attenuation at 500 kHz is about 20-25 dB. This is not a problem for casual broadcast band DXing. However, we also provide a way around the T/R switch: the RX ANT IN jack on the KXV3 or KXV3A module. Most broadcast-band enthusiasts connect their low-band receiving antenna directly to RX ANT IN, bypassing the high-pass filter. If you still have a particular station that's a problem, you could use an external notch filter in line with RX ANT IN. 73, Wayne N6KR On Nov 15, 2010, at 3:33 PM, Karl Marderian wrote: > > > Sent from my iPhone > > Begin forwarded message: > >> From: Karl Marderian <[email protected]> >> Date: November 15, 2010 3:23:33 PM PST >> To: "[email protected]" <[email protected]> >> Subject: FT5000 PIN Diodes >> > >> As I remember, when I bought my K3. I want to receive AM, even down >> to the low broadcast band. I was told that I needed the optional >> receive plug. This was to bypass the PIN Diodes. >> Maybe this is why Yeasu did not use them. >> N6XVT. Karl ______________________________________________________________ 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
