[Lowfer] Icom R-75 Specs

[ToddRoberts2001 at aol.com]

Hi All,
>From my experiences the Icom-R75 is an extremely good receiver
down to around 100KHz and slightly lower. I have noticed degraded
sensitivity and spurs much below about 80Khz but Icom only
guarantees the specifications down to 100Khz.
 
John Reed gives the R75 overall good to excellent ratings above
200KHz.
 
No matter what receiver I am using, if I am interested in DXing
VLF frequencies much below 70-80KHz I have always gotten
better results by using a good LF-VLF converter in front of the 
receiver. Even high-end receivers like the Harris RF-590 have
degraded specs much below about 60KHz or so.
 
I have built several high-end LF-VLF converters using the
AMRAD design and adding a high-stability 3MHz OCXO
oscillator for the LO. This converts the 0-500KHz frequency
range to 3.0-3.5MHz where most communication receivers
have excellent specs. The 3 MHz OCXO is stable well
within 1Hz after a short warmup and preserves the 1Hz 
frequency readout of a good receiver and is stable enough
for QRSS work.
 
My favorite design feature of the R75 is the excellent I.F.
ultimate rejection, especially when using a matched pair
of filters in the 9MHz and 455KHz I.F.s There is practically
no leakage around the I.F. filters that I can hear and when used
 with the AMRAD clone converter it is one of the best setups I 
have ever used for DXing VLF signals like the 17.2KHz 
Grimeton transmissions. 
 
Leakage around I.F. filters bugs me more than just
about anything else in an otherwise good receiver and 
the R75 is better than almost any other receiver I have
used in this regard.
 
73 Todd WD4NGG