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#1
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I think you should buy the preamp if you think you will like it. I think
that the reason nobody on this NG seems to have the Kiwa preamp is because they all have decent receivers. With a halfway decent receiver, you don't need a preamp. The trend in recent years has been to use NO RF amplification ahead of the 1st mixer. In the tube days, an RF amp was generally needed, because of the use of pentagrid convertors, etc. Exceptions were the R390 (at least the 1970s unit I had), which used a 6C4 1st mixer, the Squires Sanders IBS Superhet and their amateur version (SSR-1 or SS1-R?), which used a 7360 balanced mixer. If you have a good NF, there is no need for a preamp. A case in point...........even though the Kiwa preamp, which is very good, has an IP3 of +34dBm, the gain that the preamp provides still degrades the IP3 of the receiver itself by that same amount. +34dBm is ok for a high level preamp, but it is possible to design an RF preamp that has a +40dBm IP3. In all fairness to Kiwa, the preamp is very reasonably priced. I once looked at a schematic of the regenerative preamp for the Kiwa loop.............a very good design. The things they were doing with the high performance ceramic filters were very good. Too bad Murata decided to discontinue everything but their 4 and 6 element ceramic filters. Pete wrote in message ups.com... do you know how to spell ? (besides being gross) |
#2
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In article ,
"Pete KE9OA" wrote: I think you should buy the preamp if you think you will like it. I think that the reason nobody on this NG seems to have the Kiwa preamp is because they all have decent receivers. With a halfway decent receiver, you don't need a preamp. The trend in recent years has been to use NO RF amplification ahead of the 1st mixer. In the tube days, an RF amp was generally needed, because of the use of pentagrid convertors, etc. Exceptions were the R390 (at least the 1970s unit I had), which used a 6C4 1st mixer, the Squires Sanders IBS Superhet and their amateur version (SSR-1 or SS1-R?), which used a 7360 balanced mixer. If you have a good NF, there is no need for a preamp. A case in point...........even though the Kiwa preamp, which is very good, has an IP3 of +34dBm, the gain that the preamp provides still degrades the IP3 of the receiver itself by that same amount. +34dBm is ok for a high level preamp, but it is possible to design an RF preamp that has a +40dBm IP3. In all fairness to Kiwa, the preamp is very reasonably priced. I once looked at a schematic of the regenerative preamp for the Kiwa loop.............a very good design. The things they were doing with the high performance ceramic filters were very good. Too bad Murata decided to discontinue everything but their 4 and 6 element ceramic filters. The only reason I can see for a pre-amp would be a very low gain (small size) antenna such as a small loop. A table top radio with a full size antenna would probably not get much benefit from an amplifier. The only other exception to this was the very low noise surroundings example previously posted. -- Telamon Ventura, California |
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