Hi all,
Imagine… there are still people fiddling with “classic” conversion HF receivers
!
Martein, PA3AKE, has just updated his web site to show the test results of the
AR7070 up conversion radio.
The AR7070 has been designed by John Thorpe the designer of the highly acclaimed
AR7030 HF receiver and also the designer of the 'HF' series of receivers made in
Matlock by Lowe Electronics in the late 1980s and early 1990s.
IP3 dynamic range at 200Hz is 97 dB with an IP3 of 19dBm in a 2.4 KHz bandwidth.
This rises to 115dBm at 50 KHz with IP3s around 46 dBm. The receiver has good
sensitivity with no preamplifier before the first H mode mixer so for the 7Mhz
band running with a 5 dB attenuator would put IP3 over 50dBm.
Martein presents in tabular form all the performance measurements that have been
made by John Thorpe the radio’s designer. There are also comments by Colin
Horrabin, G3SBI and Martein.
Basically this receiver is an up conversion CDG2000 receiver.
To illustrate a particular point the AR7070 is compared with the review, by
Peter Hart G3SJX, of the Yaesu FTDX5000 measured close in IP3 on the 7MHz band
using the down conversion receiver. He did these tests with different roofing
filter bandwidths. The test, using a 15 KHz wide filter, clearly showed that the
IP3 within the roofing filter bandwidth was only -8.5 dBm. With the receiver
noise figure being around 20 dB this gives a close in IP3 dynamic range of only
77dB compared to the AR7070s IP3 +19 dBm and 97 dB dynamic range in an SSB
bandwidth.
Take a look at the results and you will be surprised:
http://www.xs4all.nl/~martein/pa3ake/hmode/ar7070-proto2.htmlIt should prove to be the best up conversion radio of all time.
73
Gian
I7SWX
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