There are two sets of modifications for the Drake 2880 downconverter. Masa, JN1GKZ, shows how the standard converter is made to receieve 2400 MHz and how to change the I.F to 144MHz.
My article shows improvements to noise figure and gain to provide typically 2.1dB system N.F. and 30dB of conversion gain. Both articles are on the "World above 1000 MHz" web site of Peter G3PHO who is the editor of the RSGB Microwave news letter.
G3PHO "Lower noise and Higher Gain for the Drake 2880"
DRAKE FILTER Remove that lossy stripline filter and get 1.95dB Noise figure
DRAKES & DEM Powering your DEM pre-amp from the Drake -and no extra holes!
Another 'little bit of fun' was to remove the Drake FET and replace it with an ATF36077. This is not an easy modification as you have to construct a negative bias supply. However, the first test was a disappointing 3.6dB, then I cut the PCB open circuit stub on the output of the device and the noise figure fell to 1.77dB......Now that's more like it! Perhaps with a little more playing I can get this down to 1.0dB maybe less!
Additional notes on 2302 and 2320 operation are also available on the G3PHO site
A Kit of components for the 'MRF modifications is available at £7.50.
(MGA86576, SM inductor, zener, pins, 22pF)
P+P for the worldwide is included
I have also have 8.81250MHz crystals made for the conversion to a
144MHz I.F. These are available at £9 each- post included.
If you order one from a local manufacturer then you'll need to specify a 15pF load capacitance and a height not exceeding 11mm. Crystals for 2320MHz should be 8.5000 MHz
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