Hi ian, Gee thanks for the insight to your attempts on an internal pre-amp.
I imagine that the lack of sensitivity on 12/15M has appeared after production also so again the position would be the same from Elecraft. It is a pity that to correct this can only be remedied with an external device. If they ever produce a remote 10/12M preamp that could be sat a foot or so away from the K3 this would help in my case but may not suit home stations and others. I realise I am most likely in a small minority here and I accept that without reservations. I would rather pay for what I need rather than a combo including 6M which is of no use to me. 73 Gary On 26 May 2013 19:39, Ian White <[email protected]> wrote: > 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 > -- *Gary - VK1ZZ Skype: Gary.VK1ZZ Motorhome Portable The Shack* *Elecraft K3 P3 Panadapter KPA500FT KAT500FT** KX3-K * ______________________________________________________________ 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
