Joe, Gary and Joe again: >>> >>> I agree that an internal preamp (or premps) would be ideal. However, >>> in addition to the preamp(s) Elecraft would need to provide *another* >>> design for the KXV3A - one that switches the RX ANT IN/OUT >>> connections to internal jacks - as neither the original KXV3 or >>> current KXV3A have that capability. >>> > > > let's not let that technical inconvenience reduce in any > >way my hope for a cure to my sometimes demented desires....:-) > >I'm not saying it isn't possible ... takes one additional relay and two >connectors. There are even couple unused control lines on the KXV3A that >could be used to control the added relay and switch bands (10/12 and 6 M) >if necessary. >
Been there, tried that. I tried two different ways to retrofit an internal preamp for 6m, and neither of them worked well enough to keep. The problem is that any modification has to work within the very tight space behind the rear panel of the KXV3 module. There is >>barely<< enough space to install a tiny PC board behind the RX ANT IN and RX ANT OUT connectors, with very tight limits on what can be included on that board. The track layouts had to be designed with a step size of 0.025in and in some places the tolerances were even tighter than that. Board #1 used a single subminiature DPDT relay and included a very simple wideband preamp; but the single relay gave insufficient isolation to prevent the preamp from oscillating out-of-band. There wasn't enough space on the board for two relays, tuned circuits or any additional shielding and decoupling; and it was impossible to make any further tweaks without completely extracting the KXV3 module. Board #2 was simpler, this time with two DPDT relays for improved port-to-port isolation, and with two coax fly-leads that were long enough to reach into the space above the KRX3 module (which Elecraft had reserved for the 144MHz transverter). That allowed me to use a fully shielded 6m preamp which gave a dramatic improvement in sensitivity - but now the VFO encoder noise made it impossible to tune the band! I believe that new problem was due to the use of two different grounding points, at the KXV3 and on the top cover of the KRX3, and I couldn't see any way around that. At that point I gave up on the idea of retrofitting an internal 6m preamp. Elecraft could have included it at the initial design stage, of course; but if my reading of history is correct, the demand for greater sensitivity on 6m came >>after<< the K3 had been launched on the market. By that time the internal hardware design was already locked down, so I can fully understand why Elecraft were obliged to produce the PR6 as an external add-on. Wayne has acknowledged that the K3 can sometimes be lacking in sensitivity on 6m, and has stated that the external PR6 module is Elecraft's solution. I wouldn't expect that position to change significantly. 73 from Ian GM3SEK ______________________________________________________________ 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
