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Old August 30th 06, 06:59 PM posted to rec.radio.shortwave
Tom Tom is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 58
Default Local Interference


Kevin Garrett wrote:
"Tom" wrote in
Kevin, this is VHF image interference related to the 1st IF of 45 MHz.
The 1st local oscillator is at 52.1 MHz to tune in 7.1 MHz- -
difference equals 45 MHz, but 97.1 MHz also produces a diff of 45 MHz.
While the DX-394 does have a filter in the Lo-Z input to suppress
signals above 30 MHz, its stop-band attenuation is not enough to
prevent strong VHF signals from breaking through. Add an ouboard 30-40
MHz lowpass filter in the coax line between the antenna and LO-Z input
to increase the VHF attenuation.

Also, for more info on the DX-394, join the user group at
http://groups.yahoo.com/group/RADIOSHACKDX394/ .

Tom


Thanks Tom

Would that be something like this? http://www.grove-ent.com/FTR-FM.html


That would work to attenuate the VHF-FM band only but is probably
rather pricey and will kthelp if you have images from VHF aeronautical
band et al from 108-120 MHz. Look on ebay for ham/CB TVI low pass
filters designed to pass everything below 30 MHz and to attenuate
above. Here's a search URL:
http://search.ebay.com/search/search...6c atref%3DC6

Good luck,

Tom