> > In that case the BDR would be 111 dB, would it not? I believe the K3 was > measured at BDR of 140 dB at 2 kHz spacing on 14 MHz in the most recent ARRL > test. Not that we would actually try to operate so close to such a strong > signal on CW due to key clicks, etc, but BDR results at wider spacings are > very important if there are other stations on the same band (e.g. one on SSB > and one on CW in Field Day or during a DXpedition like VP6DX, or if you had > a close neighbor on the same band).
You are not replying my question, Bill. I've simply asked if you are able to listen to a -105 dBm with a + 7 dBm inteferer placed at a 2 kHz offset with your receiver. You have two choices: 1) No, I can't. 2) Yes. I can. If the reply is #1 you should explain me why if the BDR of your receiver is declared to be 140 dB at 2 kHz spacing and you are not able to do handle a 111 dB signal dynamic range. If the reply is #2 I kindly ask you to provide me the proof and I will apologize with you. BTW, if in a real situation nobody would try to operate 2 kHz apart a strong CW signal, due to the clicks, what the ARRL Blocking Compression Gain test at 2 kHz is meant for? Is it for dummies? Don't you think that questioning the utility of the test while being so proud that your receiver is rated with that figure is a really poor argument? Can you briefly explain why you feel ARRL's definition of BDR below is not > correct? ...The blocking dynamic range is the difference between the level of the > noise floor from the level of undesired > signal that produces a 1 dB decrease in a weak desired signal... > I already know the ARRL definition. What "weak" means? Is it a signal at the MDS level, 20 dB stronger, or 50? Weak is not 1 foot, nor 2 inches/second. It is NaN, not a number. For DXers weak means S 8, for others it is right the MDS, for other it is the level of the least audible CW signal immersed in the noise, say 10 dB less than its power. If "weak" is meant to be S 8, be sure your receiver has a 140 BDR, as defined by the ARRL, but I kindly let you note that the difference between 10 dBm (the level of the interfering carrier that produce a 1 dB decrease in the weak signal in a receiver which has a sensitivity of -130 dBm) and -79 dBm (the weak S8 signal) is not 140 dB, but just 89 dB. Do the same test with a weak desired signal which is S 4 and let me know if you are able to measure the gain compression of your receiver or if instead you simply you are not, just because the phase noise of the LO is 20 dB higher and has already completely desensitized your equipment. In the case you are not able to do it, why do you claim that your receiver can handle a 140 dB dynamic range if it is not able to handle signal level differences which are much less? 73, Nico Palermo, IV3NWV
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