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Noise blanker demo
- Thread starter w9cll
- Start date
Do you have any way of knowing what the source of the noise was that you were able to get rid of by using the NB in that demo? The demo seemed pretty effective but it would be nice if we could see the same demo performed with an intelligible signal present at the same time.
forgive me if i compare to a cb radio..but its a good example when it comes to a NB
the yaesu nb
the difference is WHERE the NB is located in the rx chain...most real ham transceivers the NB is within the I.F chain after the mixer just before the main I.F filter.so works at the IF frequency after all the out of band crap is already filtered out by the bandpass filers and usually has agc compression of some sort
Somewhat more sophisticated than a cb style NB circuit which is in reality just a parallel frontend with clipping tuned for below the frequency range of the cb radio (usually 23/24 mhz ) ..
This would be a problem with multi band transceivers with broadband bandpass filters that dont have preselector tuning like the ft10zd and similar aged radios in the front end rx chain(requiring a nice big board full of NB strips for each band so they put it down the rx chain in a more senseable spot)
making one like the yaesu one for a cb radio would greatly add cost to production ..al thou it can be done (hmm after market nb unit ..would that sell?)
old story for every buck it costs to make it is 5 bucks the customer ends up paying
where as in a cb radio its between the front end and the mixer before it even gets to the I.F chain where the circuity is board banded so therefore less effective but most cost effective for that market(lets face it cb's and cbers are cheap..they dont want to spend money on a good RX just a roger beep and more echo and a extra watt before a decent NB circuit
i do love the variable blanker in my ft107dm..makes hf a pleasure
however like the FT101z/zd nb if turned up too far to combat the noise a strong signal (say ssb contact) will pump the blanker too much resulting in distortion of the said stations incoming signal ..a trade off but manageable
the yaesu nb
the difference is WHERE the NB is located in the rx chain...most real ham transceivers the NB is within the I.F chain after the mixer just before the main I.F filter.so works at the IF frequency after all the out of band crap is already filtered out by the bandpass filers and usually has agc compression of some sort
Somewhat more sophisticated than a cb style NB circuit which is in reality just a parallel frontend with clipping tuned for below the frequency range of the cb radio (usually 23/24 mhz ) ..
This would be a problem with multi band transceivers with broadband bandpass filters that dont have preselector tuning like the ft10zd and similar aged radios in the front end rx chain(requiring a nice big board full of NB strips for each band so they put it down the rx chain in a more senseable spot)
making one like the yaesu one for a cb radio would greatly add cost to production ..al thou it can be done (hmm after market nb unit ..would that sell?)
old story for every buck it costs to make it is 5 bucks the customer ends up paying
where as in a cb radio its between the front end and the mixer before it even gets to the I.F chain where the circuity is board banded so therefore less effective but most cost effective for that market(lets face it cb's and cbers are cheap..they dont want to spend money on a good RX just a roger beep and more echo and a extra watt before a decent NB circuit
i do love the variable blanker in my ft107dm..makes hf a pleasure
however like the FT101z/zd nb if turned up too far to combat the noise a strong signal (say ssb contact) will pump the blanker too much resulting in distortion of the said stations incoming signal ..a trade off but manageable
A lot of noise blankers will cause distortion on strong signals. I simply turn the RF gain back or adjust the blanking level to reduce/eliminate the distortion.