RE: [linrad] 2 questions

[Kohjin Yamada <jr1ede@xxxxxxxxxxxxxxx>]

Hi Roger, Conrad and all,

Just one cent drop:

At 20:44 02/10/13 -0400, W3SZ wrote:
>I don't plan to just use any one receiver.  I am enjoying playing with
>and comparing my homebrew receiver and the Time Machine, and I plan to
>play with all 3 once I receive the WSE RS2500.

It should be interesting for us to hear the comparison.
I definitely believe no one can beat RX2500 although you better do this
in weak signal detection.
On my just a first glance on your S files presented it looks similar or
there is no big difference than Leif's S record made by his old receiver.
However this comparison (my glance) is of extremely weak signals
and rather high level HF/VLF signals, we must take this in account.

>So the only thing you missed was my plan to keep using all of the
>hardware rather than only using the RX2500 after it arrives.  And my
>wanting to solve the problem so I don't need to keep swapping cables
>until the RX2500 arrives.  Since I have pretty much ended up using
>Linrad as my receiver for everything (LF, HF, and VHF and up) this cable
>swapping occurs pretty often. ;)

Conrad, Roger is referring to;
"Time Machine" from Expanded Spectrum Systems;
http://www.expandedspectrumsystems.com/prod2.html
You can reach their manual and circuit diagram there.
A 16V8 (U9) needs 4*F input so to produce quadrature 90 degrees
phase shifted output for a pair of TUF-1 I/Q mixer LO.
I'm afraid 4*F produces much degraded phase noise especially
on higher frequency, 144MHz (576MHz) for example.
I would say in my honest, don't waste your time!
Maybe Leif will clear this shortly.

>As for the PS, I can get my hands on a very nice commercial unit that
>will handle 1.5 amps, for a really good deal.  That could then replace
>my homebuilt device.  But I can't get such a deal on a commercial 3 amp
>device (or anything other than the 1.5 amp unit).  That is why I was
>being so parsimonious with the ma's.  Getting 2 1.5 amp units would make
>the deal much less attractive.  My homebrew +/- 15 V unit that I use
>with the homebrew receiver works fine, but I can't resist a good deal.
>;)

I think the power supply is very important.
It should be very clean at least so not to degrade the noise performance
of the equipments. A deal is a deal.
I even think comparison of switching and linear power supply.
Please someone add to this field as I've been very serious in this matter.

Kohjin - JR1EDE



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