Hi Pete,

I usually learn something useful from your postings and enjoy reading about
the repairs and mods you've made and the progress on the MW receiver. I've
got some questions you might be able to help me with regarding the DX-394
and intermod. I'm wondering what one might do to improve its strong signal
intermod performance.

It uses HSU277 diodes to switch among 3 SW preselector bands and 1SS272
diodes for the LW/MW bands. I have nearly doubled the reverse bias and
forward current by switching from the 7V supply to the 13.8V supply with
little obvious benefit. At best, I can shove 10-12 mA through them. Is there
any point in changing the diodes? If so, what would you suggest? I think
SMD's are preferable so as not to degrade stray coupling.

The RF preamp is a 3SK195 and the 1st mixer uses a pair of these balanced
for RF and driven in parallel by the LO. Is there any point in paralleling a
second 3SK195 (piggyback style) on the preamp? on the mixer? Or changing out
the transistor type? How would one determine/set the correct operating
point?

The 1st IF (45 MHz) filter is a 2-pole crystal filter with 15kHz bw at -3dB,
100kHz at -24 dB. I acquired a 30kHz/-3dB, 120kHz/-40dB matched pair that I
was thinking of substituting in order to widen bandwidth for DRM. Note that
the centre of the 2nd IF tunes across a 5kHz segment of the 1st IF passband
so that a 10kHz or wider bw at the 2nd IF rolls off on one side or the other
because of the shoulders of the 15kHz 1st IF. Is this a bad idea for
intermod? The stopband attenuation is going to be poorer out to maybe 50-60
kHz bw but should be better beyond that, apart from stray coupling due to
squeezing in a pair of filters where one would ordinarily be.

What are your thoughts?

73, Tom