> A 50-ohm match is not required in any case.
ThatÂ’s not exactly true. With devices like LP-Pan or SDR-IQ that have 50 Ohm inputs connected to what is a high impedance output, the transfer loss (antenna to IF) was still in the range of -6dB even with the N8LP modification. The rest of the solution was to use a Clifton Labs Z-10000 buffer amplifier (high impedance input) in a unity gain configuration, install a 4:1 or 9:1 (step down) transformer, or modify the SDR-IQ for a 200 Ohm input. 73, ... Joe, W4TV > -----Original Message----- > From: Alan Bloom [mailto:[email protected]] > Sent: Tuesday, August 25, 2009 4:17 PM > To: [email protected] > Cc: 'Eric Swartz - WA6HHQ, Elecraft'; [email protected] > Subject: Re: [Elecraft] K3 Future Factory Hardware Updates; + > New beta f/w release 3.27 > > > The resistor change increases the IF output signal by a > little over 10 dB. > > It's interesting to note that changing the FET source > resistor does not result in a 50-ohm output impedance because > the resistor is in parallel with the FET source resistance. > A 50-ohm match is not required in any case. > > Al N1AL > > > On Tue, 2009-08-25 at 16:11 -0400, Joe Subich, W4TV wrote: > > Eric, > > > > > Please note that the last item, the IF Output Buffer Gain mMod, > > > is slightly different than the similar N8LP mod some have been > > > performing on their K3s independently. We determined that only > > > one value needs to change to implement the gain increase for > > > the IF output. We are changing R8 from 1K ohms to 13K ohms. > > > > Are you saying it is not necessary to increase the current in > > J309 to handle the higher signal levels? > > > > With this change, what is the transfer gain/loss from the antenna > > input to the IF output with the IF output terminated in 50 Ohms? > > > > 73, > > > > ... Joe, W4TV > > > > > > > > > -----Original Message----- > > > From: [email protected] > > > [mailto:[email protected]] On Behalf Of Eric > > > Swartz - WA6HHQ, Elecraft > > > Sent: Tuesday, August 25, 2009 1:53 PM > > > To: [email protected] > > > Subject: Re: [Elecraft] K3 Future Factory Hardware Updates; + > > > New beta f/w release 3.27 > > > > > > > > > Hi Roy, > > > > > > As of today, we have made the following enhancements to all > > > K3s leaving > > > the factory: > > > > > > K3 VFO TUNING NOISE REDUCTION (requires f/w 3.25 or later) K3 > > > AUTOMATIC FRONT END PROTECTION (1 wire mod) K3 IF OUTPUT BUFFER > > > GAIN MOD (For the P3, LP-PAN etc) (1 resistor value > > > change) > > > > > > Based on feedback form those that have tried the preliminary > > > release of > > > these changes, we are comfortable with adding them as > > > standard K3 features. > > > > > > Please note that the last item, the IF Output Buffer Gain mMod, is > > > slightly different than the similar N8LP mod some have been > > > performing > > > on their K3s independently. We determined that only one value > > > needs to > > > change to implement the gain increase for the IF output. We > > > are changing > > > R8 from 1K ohms to 13K ohms. (Those that have made the > N8LP mod may > > > also leave it as is.) > > > > > > Also, we are releasing new beta f/w today, MCU 3.27/DSP > 2.24. This > > > is > > > already available on the web page at: > > > > > > http://www.elecraft.com/K3/k3_software.htm > > > > > > This release includes: > > > > > > *ADDITIONAL NOISE REDUCTION (NR) IMPROVEMENTS. > > > *AUTONOTCH depth improved. > > > *SHIFT=.01 FIXED WITH LOW SIDETONE PITCH (300 Hz). > > > *VFOs NOW TUNE DOWN TO 490 kHz. > > > > > > We never sleep in Aptos! :-) > > > > > > 73, Eric WA6HHQ > > > > > > Roy Morris wrote: > > > > I would like to know if is the intention of Elecraft to > > > > incorporate > > > > the K3 AUTOMATIC FRONT-END PROTECTION mod and the K3VFO > > > TUNING NOISE REDUCTION mod in future PC boards. If so, I > > > plan to install these mods in my K3s. Roy Morris W4WFB > > > > > > > ______________________________________________________________ > > > 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
