[600MRG] Flex-5000A or Flex-1500

[Eric Tichansky]

A few observations I've made over the course of several weeks using a 
Flex1500.

The primary reason I decided on a Flex1500 was the ability to use an 
external 10MHz reference (ie. GPSDO).  Prior to having the Flex1500, I 
used my Elecraft K3 w/ transverter.  The transverter LO is 10MHz from 
the GPSDO source, the K3 also has the K3EXREF 10 MHz reference module, 
also sourced from the GPSDO.  The problem with the K3 is that the 
K3EXREF leaves much to be desired and is a rather poor implementation of 
a reference.  When running QRSS at the 2200M watering hole, the K3 would 
jump around 1 Hz periodically.  That is quite unacceptable when other 
stations are 0.5 Hz apart and you end up landing right over top of 
someone.  The accuracy is also not so great; I always had to compensate 
for the absolute frequency error by adjusting the audio tone in Spectrum 
Lab when running QRSS.  The Flex1500 has no such problem, keeps 
consistent stability and accuracy (always around 30 mHz) when sourced 
form the external reference.

However, the K3 seems to have the more desirable receiver.  With both 
the K3 and Flex1500 receiving through the same transverter (and 
obviously the same antenna) using a magic-T splitter, the K3 resolved 
XPQ in Alaska much better than the Flex (per comparison of Argo 
captures).  I also found copying XIQ during a CW QSO where he was 
starting to fade out was much better on the K3.  However, my Flex1500 is 
monitoring WSPR-15 on 136 kHz now, decoded DK7FC, so I suppose the 
Flex's RX isn't that bad.  A more subjective test would be in order to 
really give a purposeful evaluation.

The Flex was a PITA regarding a USB triggered problem that would trash 
the audio chain, emitting loud noise or a high pitched whining until it 
was power cycled.  The resolution was to insert a USB hub between the 
Flex1500 and PC.  I suppose this is my PCs fault, crummy USB, despite 
being a reasonably good PC.  There are also occasions when the audio 
blips, making unattractive traces on QRSS in Argo, but that's probably 
nit picking.

I have not tested the Flex w/o the transverter yet other than a quick 
test w/ RX.  It will run natively on 630M, but needs an LPF to block 
BCI, otherwise, the band is covered in IMD, et.al.

In the next day or so, I will be testing a Genesis Radio G11.  They are 
now offering it for 600M.  10W output, no transverter needed.  It looked 
interesting enough to try.  it uses a port of PowerSDR called GSDR.  
There is no method of locking to a reference, so it is more of a general 
purpose rig, but should suit fine even for WSPR, JT9-X, etc.  Not overly 
excited about the fact it's SDR based on anomolies w/ the Flex, but 
maybe I'll be surprised.

73 - Eric NO3M, WG2XJM