Geez I'm so stupid,
My fingers typed exactly the opposite of what my brain was [Not] thinking.
I meant to say that since the Scout had better MDS specs and worse BDR
specs(compared to a TS 50) that theoretically the TS 50 hears a bit better
but the Scout handles strong signals better. I was wondering what that
meant as far as actual operating. Your example of the field day comparison
makes the numbers more real.
As far as "phase noise" Yes, that doesn't make any sense. The Elecraft
page shows phase noise for the Scout but how could a PTO have phase noise?
I checked the original QST article and nothing is mentioned about phase noise.
I wonder if anyone has had field experience comparing the 706,TS 50 and
Scout?
I had been wondering if reducing the hiss would result in increased
Minimal Discernable Signal; but if I understand this correctly, one does
not effect the other because the hiss is being introduced at an audio level
while the MDS is an RF measurement? Therefore,the hiss is not very
important and doesn't actually affect the ability to detect a weak
signal(?) If the hiss is objectionable it can just be eliminated or at
least attenuated at the audio stage ?
73
Bob, KB12CIW
At 01:34 PM 3/5/02 -0600, Stuart Rohre wrote:
>Bob,
>First of all to correct some misinformation. There is NO phase noise in a
>Scout. It can't have any, for it is a Permeability Tuned Oscillator, ie
>PTO, an inductor with screw adjustment, and capacitor to tune a frequency as
>the BFO. Phase noise is an artifact of Digital Frequency synthesis, a whole
>different animal.
>
>I am not sure what the ARRL charts says, but as you presented it, the TS 50
>with better MDS, means minimum discernable signal, while BDR is Blocking
>Dynamic Range. Now, from personal use of a TS 50 at Field Day and a Scout,
>I can tell you the TS 50 has TERRIBLE strong signal performance, ie is
>swamped by nearby strong stations, and this is what BDR measures. The Scout
>on the other hand can operate right next to another Field Day site, and hear
>anything there is to be heard.
>
>There was no change to the microprocessor which would affect either of these
>measurements, which are RF chain based. The micro operates on the keying
>and the frequency counter, essentially well below the IF, and a high audio
>type of thing.
>in its rate of switching.
>
>If one uses the external speaker jack on a Scout for hi fi headphones you
>may hear at low volume, ie with no signals coming thru the receiver, the
>audio tones of the micro. This is an audio chain artifact. It can be
>eliminated by using communications (limited frequency response) phones, as
>you should on any short wave radio. Especially effective are my HS 32
>military phones, which are 15,000 ohms impedance, but 2000 ohms phones like
>are sold for xtal radios at Antique Electronics Supply, Tempe AZ will also
>do well. It can also be eliminated by using the resistor pads TT suggests,
>if you are going to use hi fi (8 ohm or 32 ohm) phones on the speaker
>connection. A series 100 ohm resistor in each leg fixes the sound so that
>you do not hear the micro. Some Scouts, (mine) do not hear the micro
>anyway, apparently due to some change in filtering of the B plus that was an
>early production change. There is now a capacitor and ferrite core filter
>on my B plus lead, inside the back of the radio. All should have this.
>But, I think some early ones did not from the TT archives I read.
>
>The rig came out in 1991?, I do not think any CPU changes were made in 1993.
>At least, no one has reported that in some 7 years of this reflector that I
>looked up yesterday evening. I file all the Scout info in a folder for
>Scout, and that was my basis for saying that. In fact, since my rig was
>built somewhere around 93, or 94, and has the RFI bead on the B plus, I
>think that was the last change to the design. Of course, maybe they did
>something that no one was told, and maybe no one has dissected, but as much
>as Scouts have been discussed on this reflector, over some 7 years I
>documented, it would likely have come up.
>
>The TS 50 also had a loud spurious harmonic, and essentially our club no
>considers them unusable for Field Day.
>Incidentally, the TS 50 problems were noted in a 2A Field Day, ie only 2 HF
>stations in proximity and a Novice station intermittently being used.
>Antennas were beams for 20 to 10, and dipoles and vertical. I believe the
>50 was on an all band R7 vertical at the time, well away 100 yeards from the
>dipole, and ground mounted below the firing angle of the beam. The 50 could
>benefit also from more intuitive controls, you have to find hidden menus to
>change many parameters.
>
>73,
>Stuart K5KVH
>
>
>
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