I tried that more then 40 years ago, in the early sixtees with a quad diode mixer and a 6J6 oscillator tube with two outputs, 1 direct and the other via ~28cm 90 Ohms coaxial cable for the 90 degrees shift. It worked in principle but it was not a great succes. The diodes were Ge types and not suited for high frequencies. Then I switched to FM by building an 8MHz VFO in a thermal controlled alluminum box, FM modulated it and multiplied it to 144 MHz. but at that time nobody had a discriminator in their 2 meters receiver, only a Danish station and that worked! Slope discrimination did not work good enough in the wideband AM receivers of that time. Don't let this discourige you because after that we started grinding X-tals to make an X-tal filter that could, together with a diode balanced modulator, be used to suppress respectiovely one sideband and the carrier to produce SSB. The fine tuning of the X-tal filter, by grinding it up or pencelling it down in frequency, was done in QSO's for the best legetability (or is it legability or even legetamability?) Well that's history but it was necessary to reach our contempory technical status. 73 es gd Dx with softrock. Henk, PA0KEP
, "Ray" <[EMAIL PROTECTED]> wrote: > > Wondering if a FM encode/decode has been developed - most the folks on 144 > use FM for casual comms and SSB for serious stuff > > > > 73, Ray, N0FY > > SKCC 3704 > > FH 997 > > > > > > _____ > > From: [email protected] [mailto:[EMAIL PROTECTED] On > Behalf Of Terry > Sent: Thursday, May 08, 2008 4:32 PM > To: [email protected] > Subject: [softrock40] Re: softrock for 2m? > > > > --- In [EMAIL PROTECTED] <mailto:softrock40%40yahoogroups.com> ups.com, > Matt Patterson <mattpatt@> wrote: > > > > > > I know you could use a 10m softrock and a transverter to get on 2m SSB > > but I was curious what would be the feasability of actually designing > a > > softrock for the 2m band. > > > > 73 Matt > > W5LL > > > > The QSD switches typically don't go that high. Plus, its harder to > find a low phase-noise LO that high. > > But, I just tried a Brainerd 995X receiver board at 144.000MHz with 1/3 > subsampling (the 995X board is tuned to 48MHz). The MDS is around - > 110dBm. There are quite a few spurs, but my board is sitting out in > the open on the bench. Absolutely no shielding or filtering being used. > > Using 1/5 subsampling (QSD tuned to 28.8MHz) the MDS is around - > 100dBm. There are fewer spurs & artifacts there. > > So, it's possible. Downconverting to around 30MHz is probably a better > choice. > > Terry > WB4JFI >
