Paul--
One option to see HF with your VHF only CATV FSM is to use an HF
upconverter designed for SDR dongles like the FunCube. This puts the
entire HF spectrum into the low VHF band.
Do a search on Amazon or Google and you will see them for about 50 bucks.
Ham It Up v1.0 - NooElec RF Upconverter For Software Defined Radio.
Or go directly to the nooelec website and get it for $40
nooelec.com/store/software-defined-radio/sdr-accessories/ham-it-up-v1-0-rf-upconverter-for-software-defined-radio.html
Or skip the CATV FSM and go directly to the dongle (less than $40)
and upconverter. This will limit your expense to less than $100
(plus portable computer) and you have an SDR with a noise
calibration/reference source in the upconverter.
nooelec.com/store/software-defined-radio/eztv668-dvb-t-usb-set-for-sdr.html
John W0UN
At 09:07 AM 12/24/2012, Paul Christensen wrote:
Seasons greetings to all...
There's been enough RFI at this QTH during the last decade that I'm
looking to purchase a National HF Vector Gun and a used Radar
Engineers (RE) RFI analyzer, model 240A or 242. Or, in the
alternative, a V/UHF Sadelco FSM with video output for use with one
of the many oscilloscopes I have.
Questions:
1) Apart from the usable frequency range, is there's much difference
between the RE 240A and 242 models?
2) Loftness' book [1] goes into great detail concerning the
interface he constructed to integrate his FSM and scope together --
right down to schematics and a parts layout diagram. I would opt for
this approach since the display resolution is probably much better
then the RE's LCD displays. My only concern is that the usual CATV
FSM units only go down to about 50 MHz, the lower VHF limit of TV
Channel 2. I would hate to expend a lot of time and trouble to
construct an interface only to find another occurrence where RFI is
lumped in one HF band well below the limit of the FSM. In fact,
this just happened to me where a utility pole about a half-mile away
was arcing with greatest amplitude on 20m at an S9 level. Very
little RFI on AMBC and just a bit noticed on 10m as shown by
Tresscot in Fig. 2 of his QST article. [2]
For those of you actively engaged in RFI abatement, have you found
the FSM's limit of 50 MHz to be a drawback when using the scope
system Loftness describes?
Many Tnx!
Paul Christensen
Jacksonville, Florida
W9AC
[1] Loftness, M. (KB7KK), AC Power Interference Handbook, 2nd. ed.
rev., pp. 7/6, 7/12. ISBN 0-9653760-3-6.
[2] Trescott, M. (K3QM), "Basic Steps Toward Tracing and
Eliminating Power Line Interference," QST, Nov., 1991, p. 44.
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