RS - DX 394 on e - bay

RS - DX 394 on e - bay

Post by the capta » Sun, 07 Mar 2004 06:13:33

but think how much more you/your friend would like a "fixed" DX394.
Quote:> Hi Tom,

> I agree with you 1,000%. And I too saw the 4 star Radio Netherlands review
> of the original DX-394 prior to buying it. Between that review and what my
> ham friend thought of it (he had one of the original ones), I bought it. But
> he insisted I  find a "B" model since they were the same discontinued price
> here in Cananda. That receiver basically brought me back into SWL. I loved
> it contrary to the frequent put down in this newsgroup of that receiver. I
> added good external speakers and eventually a DSP-40 unit to it. Eventually
> I graduated to a Sat-800. Now my best friend has it and he too loves it. It
> serves his needs quite well.
> To each his/her own.

> Take Care
> Abb N
> VE3003SWL
> Windsor, Ontario, Canada

 
 
 

RS - DX 394 on e - bay

Post by mike maghakia » Sun, 07 Mar 2004 13:55:32


MY opinion is the following:

1) replace one or both of the IF filters, if both are done, a variable cap
must be added across X2 and a switch must be added to go between the
filters.
2) remove the purple wire and stop the tuning pops
3) add two caps for the Xtalk fix
4) add a cap to increase bass response
5) add a cap to further reduce AC hum

I would not do the hiss mod and I would either replace the speaker or use a
nice external one.

a lot of the other mods are a waste of time. I won't mention which they are
but I have tried most of them.

I think I recently made the worlds best DX-394 by doing all of these mods. I
used a Hi-Fi filter in the wide position, spec is 8/12. and a DX filter in
the narrow position, spec is  5/7. I can handle anything now

Mike



> > all these issues are covered by easy fixes, if you don't want to do them
> > , then the DX-394 is NOT the radio for you. My 394 is selective (mod),
> > quiet (inherently), has no pops(mod) and is a very nice radio.

> > I would pay a lot lot more than $50 for one and buy a dozen at a time if
> > I could.

> What are the main weak points of the DX-394 that need to be addressed to
> make it a decent receiver?

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RS - DX 394 on e - bay

Post by starma » Sun, 07 Mar 2004 16:01:41


> MY opinion is the following:

> 1) replace one or both of the IF filters, if both are done, a variable cap
> must be added across X2 and a switch must be added to go between the
> filters.
> 2) remove the purple wire and stop the tuning pops
> 3) add two caps for the Xtalk fix
> 4) add a cap to increase bass response
> 5) add a cap to further reduce AC hum

> I would not do the hiss mod and I would either replace the speaker or use a
> nice external one.

> a lot of the other mods are a waste of time. I won't mention which they are
> but I have tried most of them.

> I think I recently made the worlds best DX-394 by doing all of these mods. I
> used a Hi-Fi filter in the wide position, spec is 8/12. and a DX filter in
> the narrow position, spec is  5/7. I can handle anything now

> Mike

What about the strong signal overloading (intermod's) that others have
mentioned?

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RS - DX 394 on e - bay

Post by Tom Holde » Mon, 08 Mar 2004 23:09:20



>> MY opinion is the following:

>> 1) replace one or both of the IF filters, if both are
>> done, a variable cap must be added across X2 and a
>> switch must be added to go between the filters.
>> 2) remove the purple wire and stop the tuning pops
>> 3) add two caps for the Xtalk fix
>> 4) add a cap to increase bass response
>> 5) add a cap to further reduce AC hum

>> I would not do the hiss mod and I would either replace
>> the speaker or use a nice external one.

>> a lot of the other mods are a waste of time. I won't
>> mention which they are but I have tried most of them.

>> I think I recently made the worlds best DX-394 by doing
>> all of these mods. I used a Hi-Fi filter in the wide
>> position, spec is 8/12. and a DX filter in the narrow
>> position, spec is  5/7. I can handle anything now

>> Mike

> What about the strong signal overloading (intermod's)
> that others have mentioned?

That's a problem with every radio at some level, moreso with very sensitive
ones with wide tuning ranges and lower cost - that description fits the
DX-394. To the best of my knowledge, nobody has succeeded in making a marked
improvement to overload with internal mods. I experimented with increased
bias on the internal RF preselector switching diodes and obtained subtle
improvement. I have been wanting to replace them with PIN diodes but have
yet to source some suitable surface mount devices. However, I suspect the
main intermod generator is the RF amplifier or the 1st mixer.

Fortunately, huge improvement can be made by external pre-filtering; and
this is true for any receiver with an antenna input jack that suffers from
overload.

Mike, you are rightfully proud of your modified DX-394's but to assert it's
the "world's best DX-394" is an exaggeration. There are others who have
installed superior filters (narrower Collins mechanical, e.g. 2.3/4 to use
your notation) and have made the necessary changes so that the upper and
lower BFO frequencies and filter are properly aligned for true single
sideband, not the compromise you have made by placing the BFO in the middle
of the passband. That makes their modified DX-394 better than yours for
SSB/CW reception. And if that sharper filter is switchable for AM mode (a
trivial mod compared to replacing the filter), then it's better than yours
for picking out one sideband or the other in a crowded SWBC band where the
channel spacing is 5kHz.

To disparage other mods as a 'waste of time' is provocative. That reflects,
in part, your interests and values and perhaps your marketing objectives.
Elsewhere you have stated that you are not interested in SSB/CW and digital
modes - some of the other mods are of primary benefit to these modes. And to
make the claim of a "hi-fi" filter (the stock AM filter that is widely
denigrated for being too wide could be so described, too) and place so much
emphasis on audio improvements (bass and hum) without also recognising the
benefits to the quality of amplitude modulation reception of certain AGC
mods and the ANL Defeat mod seems to be inconsistent with achieving the
"best", even for AM.

"Best" for one person is not necessarily "best" for another. Cost ($ and
effort), location relative to powerful transmitters, bands/modes of
interest, etc. will all factor into each person's evaluation of a receiver
and the possible improvements that can be made.

Regards,
Tom