Eton E1 Frequency Alignment
 

I couldn't resist *gently* poking around inside my recently-acquired E1, to
try and locate an adjustment for the master oscillator that controls the
frequency display. I'd read a number of comments about individual samples
being off by 50 to 150 Hz or more, but I had not seen any postings on a
do-it-yourself alignment. My particular E1 was off by about 140 Hz after
warm-up.

After opening the radio and removing the back panel mounted PCB, I located a
small hole through a copper-colored metal cover. sure enough-- a tweak with
a small screw driver adjusted the frequency to bring the radio into a "by
ear" alignment for USB and LSB.

However, after reassembling the radio, I discovered this adjustment hole is
accessible through the left ventilation slot found under the flip-stand of
the radio. That's handy! Now there's no need for E1 owners to open the case
to adjust the frequency display.

Just use a very small slot screw driver (jeweler's type) and make small
adjustments while tuned to WWV in USB/LSB, switching between the two modes
to find the best audio balance and/or elimination of the beat tone. A
plastic tool is preferred, but it didn't seem to make any difference if I
used a metal screwdriver. This alignment seems dependent on the band or
frequency being tuned; that is, I can achieve good alignment on 15 MHz WWV,
but my local broadcast stations are very slightly off. Conversely, if I
adjust the radio for zero beat on my medium wave locals, WWV on 10 MHz and
15 MHz are slightly off. I did the final tweaks with WWV, since I expect to
tune any local MW broadcasters in synchronous AM, anyway.

This adjustment technique does nothing for the characteristic drift of the
radio while it is warming up, nor does it correct any imbalance between LSB
and USB mode offsets. Hopefully someone will discover the fix for LSB/USB
imbalance; the trimmers may reside under one of the soldered, metal
shielding covers inside the E1. Perhaps I'm expecting too much from a
portable, but the E1 excels in so many other areas it's a shame to hear the
tonal differences when switching between LSB and USB. Without these two
modes balanced, you can only adjust the frequency readout for zero beat with
LSB *or* USB, but not both.

Guy Atkins
Puyallup, WA USA
www.sdr-1000.blogspot.com