[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[linrad] H mode mixers at 144 MHz
Giancarlo did some tests with his H-Mode HF mixer at 144
Here are a couple of emails regarding his results:
following the quick test I did last evening on the
I7SWX 2 xfrm H-Mode Mixer at 144 MHz, please find here
below more detailed measures.
Tests on an I7SWX 3V Two-Transformer H-Mode Mixer with
a new squarer under study (circuit not yet released),
driven with LO signal of 0dBm. Transformers are the
ones used for the HF mixer and cores #41 (mu 850).
Signal input at 145 MHz -10dBm. The Table reports the
mixer attenuation at each IF for different Local
IF frequencies are resulting from RF signal less LO
and LO less RF signal (I hope it is clear...hi)
IF= RF- LO ATT LO ? RF ATT
MHz MHz dB MHz dB
0.455 144.4 -9 145.5 -9
4 140 -8 149 -8
9 135 -8 154 -8.5
10.7 134 -8 156 -9
21 124 -8 165 -10
45 100 -8 190 -11
70 75 -8 215 -12
100 45 -9 244 -15
A test done with a lower performance mixer, using
FST3125 (not yet released), and driven by the 74AC86
squarer circuit, as in the I7SWX two-transformer
H-Mode mixer, gave similar attenuation results but the
LO drive into the 74AC86 had to be +15dBm, from 455kHz
to 45MHz IF and +25 dBm for 70 and 100 MHz IF.
These tests demonstrate the H-Mode Mixer could be used
at 144-148 MHz. Need to do some studies on
transformers cores (suggested #61 = mu 125) and
numbers of turns to improve mixer attenuation.
I hope there are some friends of the Linrad list that
will tackle trial test at 144 MHz.
----end of Giancarlo's message
And now to try and find some time to play with these new