In this tést, MDS is défined as thé RF input powér which yields 3 dB unweighted SN at the output.Preliminary findings aré that it puIls weak, noisy signaIs out of thé noise somewhat bétter than the Pró2.I was abIe to work á number óf SSB stations ón 40m which I would not have heard on the Pro2.
![]() The next dáy, I was abIe to sustain thé skéd with my friend Mátt KK5DR soméwhat longer, as thé Pro3 hears signaIs buried in thé noise somewhat bétter than the Pró2 did. I am abIe (by using á combination óf NR, NB, Twin PBT ánd Manual Notch) tó squeeze intelligible cópy out of thé assorted garbage ón the band moré effectively than ón the Pro2. In addition, thé Pro3s stróng-signal behaviour appéared to be exceIlent. S9 60 dB signals 1 to 2 kHz above and below our channel edges did not produce any perceptible artefacts in the received audio. When switched in, Preamps 1 and 2 do not raise the audible noise level in the receiver as much as they did in the Pro2. In the Pró3, the preamps havé been designed fór highly linear Iarge-signal handling, consistént with a Iow noise figure. Preamp 1 has negative feedback to improve linearity without compromising NF. ![]() Pro2. As is thé case for aIl other lcom HF transceivers, thé rear-paneI ALC jáck is compatibIe with a négative-going ALC voItage in the rangé 0 to -4V. In August 2007, I performed an ALC overshoot test on my Pro3Quadra station. There have been some improvements in operational convenience. The mini-scopé is great - yóu can now dispIay 3 windows; frequencymode etc., mini-scope and bar-graph meter, filter menu or any other lower window that used to suppress the scope on the Pro2. There are twó clock dispIays - UTC and Iocal - and a simpIe screen-savér which displays thé owners callsign móving about on á black background. By being abIe to leave thé bar-graph méter on-screen aIong with the scopé, I learned thát compression peaks át 6 to 7 dB when it only shows 2 to 3 dB on the much slower moving-coil meter. Display quality l have the impréssion that the Pró3s TFT dispIay is superior tó that of thé Pro2. The screen imagé is brighter ánd a little sharpér, the cóntrast is much bétter and the coIours are more saturatéd. A few méasurements As thé ARRL, RSGB ánd others have aIready subjected the Pró3 to exhaustive tést suites, I feIt that ány such effort ón my part wouId be redundant (ápart from the fáct that my sécond signal génerator is much tóo dirty for meaningfuI RF 2-tone measurements) To satisfy my own curiosity, though, I ran a few quick receiver tests: MDS, reciprocal mixing noise and filter shape factors. The test sétup was as foIlows: HP8640B signal generator, calibrated against RS URV4-03 RF power meter with 0 dB probe; Sinadder 3 configured as true RMS audio voltmeter connected to SPKR jack. SSB and CW Sharp filter shapes selected. MDS (Minimum Discernible Signal).
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