[Premium-Rx] RX 331

[GandalfG8 at aol.com]

In a message dated 25/09/2009 04:11:41 GMT Daylight Time,  
l.strong at mchsi.com writes:

I have  received some advice on the RX 331. Must good some not so good. 
About 10  days ago I traded for a Tentec Rx350 which I think is a very 
good receiver  but not rated too good.. Why isn't it rated very good? 
Because they quit  making them? I hope this is all right to talk about 
the RX350 maybe not a  premium receiver? What would the RX331 do that the 
RX350 couldn't  do?



----------------------
I suspect the not too good rating might be why they quit making them and  
not vice versa.
 
In Europe and the UK they also came across as rather overpriced,  due to 
the old trick of leaving the numbers the same and just changing the $  sign to 
£, which didn't help when a JRC NRD545 could be bought new for not a  great 
deal more.
 
I really like the ergonomics of the RX350 and, to name just two factors,  
the display is great and I thought the DSP noise reduction excellent  too, 
but, for me at least, it's poorly rated for the same reason that  Walt sold 
his RX340, very user friendly, and a very usable receiver on HF,  but poor 
performance on MW and below.
 
Although a few years old now mine has rarely been out of its  box since I 
first bought it and found that it overloaded badly at LF on a  Wellbrook 1530 
with the worst mess of  cross modulation from MW signals  that I'd ever 
heard.
This was in south east England, with some reasonably strong  signals and 
the strongest, Brookmans Park, about 25 miles away, but other  "hobby" 
receivers, JRC Icom etc, coped well without similar problems.
 
At first, because it was so bad, I suspected that either the  antenna or 
receiver was faulty but after further tests on both loop and  receiver and 
talking to both Wellbrook and Ten-Tec UK it became apparent this  wasn't 
unusual with the RX350.
Judicious use of the attenuator did improve things but it would have needed 
 more surgery than I was prepared to put in on a virtually new receiver  to 
make it really usable at lower frequencies.
 
To stray even further away from premium receivers for a moment if I may,  
the main reason for the little RX320 being a poor MW and LF receiver was the  
inclusion of a quite severe broadcast band filter, no overload here just no 
 signals:-)
For reasons of economy Ten-Tec did not include the switched front end  
filters in the RX320 that they did in the RX350 so included the BCB filter to  
avoid cross modulation at HF.
The RX321, a commercial variant of the RX320 with only approx 100 units  
produced, did include switched filters and left out the BCB filter  and, of 
the three, was the only one to be reasonable at MW/LF straight from  the box.
 
A few years ago, after analysis of the RX320 front end  filtering filter, I 
discovered that the BCB section could be bypassed  just by soldering a 
100nF capacitor across it.
In order to cope with the anticipated HF overload it was easy to make this  
switchable but, in my location anyway and with the antennas I was using, 
the  expected overload never came and MW/LF performance was very much 
improved,  not quite as good as the RX321 but certainly much closer.
With that modification taken into account, and based on just my own  
receivers, the RX321 was still the better LF performer of the three, the RX320 a  
respectable second, and the RX350 a poor third.
 
Amongst the enhancements over the RX320, the  RX321 incorporated an 
improved first mixer and also had at least  seven, possibly eight, sections in the 
switched RF filter as opposed to six in  the RX350.
 
Without a detailed analysis there's no information available, as far as I'm 
 aware, on the coverage of the respective filter sections nor of the 
respective  performances of the RX321 and RX350 mixers but I suspect that 
replacing the  front end of the RX350, up to and including the first mixer, with 
that from the  RX321 would have resulted in much better overall performance 
from the  RX350.
 
Unfortunately, and coming back to premium receivers, my experience with the 
 RX350 has made me somewhat reluctant to invest in either  the RX330/331 or 
RX340, despite the generally better reports on these,  and Walt's comments 
have probably hammered the final nail into the  coffin:-)
 
regards
 
Nigel
GM8PZR