Parts for Linrad EME project.

[wb9uwa@xxxxxxxxxxxxxxxx>]

Hi All,

I am looking for US parts suppliers for my Linrad project.
It looks like I will buy a pair of TUF-1H mixers for the 144 to 2.5 Mhz conversion
from Down East Microwave for $12 each unless you have a cheaper source.
There are several ATF transistors listed in The Down East price list.
I wonder if any of these would do well in an MGF1302 circuit to increase IP3 and
lower noise temperature? I don't want to go with a cavity pre-amp.
I think my MGF1302 is ok on intermod, but I can't be sure. There have been
many unexplained instances of EME signals "not present at any polarity"
and I have 45 degree polarity steps.

For the 2.5 Mhz I Q detector, I found most of my parts from Digikey and the minimum
order is reasonable.
74ac74 $.56
74ac04 $.56
74HC4053 $1.29
74HC4052 $.78
10 Mhz crystals for around $1.00
IRL510 Fet for 2.5 Mhz pre-amp, $.94
The BF240 is only 10 cents from Harris in the UK, but they can not be had
in the US at any price. I need a US source for this or a good substitute.
It is the low noise oscillator transistor.

Is anyone else doing some parts hunting that would like to share information?

I have not totally convince myself to build a 2.5  Mhz unit rather then buy the 
RX2500 (maybe a little) , but it is looking like it would be relatively easy to build a unit
that exceeds the performance of the Time Machine and at a lower cost
by using an FET mixer instead of the schotkey mixer and using a low noise
oscillator at 2.5 Mhz. The cost in the US for the RX2500 is high after shipping
and payment method is figured in.
I still need to find the input transformers for a 2.5 Mhz amp and the T80-2, 10 uh
torroids. I will not be building the full fledged RX2500. I expect performance to
be somewhat short of that if I build it. Most of the other parts that I have not
mentioned are pretty ordinary and most likely in the junk box or at Radio Shack.

The 141.550 Mhz +20dbm local oscillator is complete. It is sufficient to drive two TUF-1H 
mixers. The plan is for single conversion from 144 to 2.5 Mhz for IQ detection. There were
no answers to my Moon-net question on mixing the two frequencies. I found another VHF
exciter board and used two stages from it. I drove the base of the first stage with one signal
and the emitter of the first stage with the other signal. The second stage amplifed and filtered
the mix. It came together easily and it did not cost anything (like $12 for a TUF-1H mixer).

73, Jim Shaffer, WB9UWA.


LINRADDARNIL