Predicting MW Intermod/Bleedthrough


m_a_schuster
 

I'm posting this to a couple of radio-related groups in order to get a wider audience of collective wisdom. I live in an area of northern New Jersey that I've come to refer to as RF Alley because of the concentration of powerful transmitter towers situated in wetlands a few miles away. The most annoying result of this proximity is rampant MW intermod and bleed-through on some, but not all portable radios which can make for frustrating bandscanning; especially on the upper end of the band.


Like many in these forums I've bought many portables over the years; held on to many and sold or returned others because of poor performance otherwise, or sometimes just because of the MW intermod issue alone. I'm getting tired of playing Russian Roulette with online purchases, and was wondering how I might predict this propensity ahead of time - but in spite of reading numerous online reviews before purchase I often fail because others' experiences doe not match mine. Can anyone see a predictive design/architecture pattern here?


SUFFER FROM SEVERE MW INTERMOD:

  • Tescun Mid-Full Size PLL: PLL660, 800
  • Degen Mid-Size PLL: DE-1102, Grundig/Eton G5/E5
  • Tecsun Ultralight PLL: PL-210
  • Redsun Ultralight PLL: CCrane SWP


DO NOT SUFFER FROM SEVERE MW INTERMOD

  • Sangean Pocket AM/FM PLL: DT 200, 220, 400; ?Ccrane AM/FM Pocket
  • Sangean Mid-Full Size PLL: ATS-505, 606
  • Tecsun Ultralight Analog: R-9702
  • Tecsun Ultralight PLL: PL-200
  • Redsun Ultralight PLL: Digitech AR1733 (and so probably the upcoming CCrane AM/FM/SW/Air)
  • Sony 1-chip analog ultralight: SRF-59, etc
  • Tecsun Ultralight/Medium DSP: PL-300, 310, 380, 390, 505, 606


Even the "immune" radios are not totally immune; for instance a local blowtorch at 1010 KHz appears at 1090 on every single radio of every brand, size, vintage, or design over the years; but I've learned to live with that.



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