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Contesting Online Forums : Tips : DBR- How Much is Enough? Forums Help

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DBR- How Much is Enough? Reply
by K2QO on August 29, 2000 Mail this to a friend!
I am an avid QRP contester, both in QRP and QRO contests. I am looking for a new rig to replace an old Argosy that has 99 dB DBR on 14MHz per the QST review. The rigs I am looking at sport specs of 115, 122 and 135 dB. Now, with simple wire antennas from a mediocre QTH, can I really expect a larger DBR to make a BIG difference? (The rigs are the TS-570S(G), IC-746 and Omni V.) The rig I prefer based on features, form factor, etc, is the one at 115 dB.
RE: DBR- How Much is Enough? Reply
by ve3iay on August 31, 2000 Mail this to a friend!
As I understand it, it depends on your RF environment, i.e. how many strong signals (e.g. nearby hams) you are likely to encounter.

In my case, there is another ham with very similar operating habits to my own (i.e. we like to operate in the same CW contests) about 1000 feet from my QTH. I use non-directional (usually vertical) antennas. I used to use a TS-180S, with a blocking DR of 114 dB according to ARRL tests. When my friend was on the air, I found it almost impossible to operate on the same band as him because I just couldn't copy anyone through the noise in my receiver in sync with his CW. When I switched to a TS-850S, with 148 dB blocking DR, my enjoyment of contesting increased, because I am now able to copy signals as close as a few kHz away from my friend's operating frequency. To the best of my somewhat limited knowledge, it is the receiver BDR that accounts for this difference (both radios are equipped with 500-Hz CW filters, dual in the case of the TS-850).

So, my answer to your question is: if there are other transmitters nearby, you can never have enough dynamic range; if the nearest ham is miles away, this particular spec may be of lesser interest.


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