[amsat-bb] Preamp source

[Zach Metzinger]

On 2019-11-08 17:17, Edward R Cole via AMSAT-BB wrote:
> ARR Gasfet preamps* sold for years at $79.xx yet cost of material are 
> rising.  Last I checked they still use the mgf-1302 yet where is one 
> able to find one?  The mgf-1302 provides a reliable 0.5 dBNF and about 
> 22 to 25 dB gain.
> 
> PGA-103+ appears to get 0.6 dB gain with about 15-18 dB gain

For those home-brewers among us:

If you just want something to fix the inherently high noise figure of a 
FM HT, you might try using, for 70cm and 33cm, the MAX2640. It can be 
obtained for ~$3.75 in qty 1 on Digikey.

Here's an application note[1] which matches it for 433MHz, close enough 
for the satellite band. They claim 1.17dB NF, which is not EME class but 
works great for the Fox satellites.

I have built up this circuit and can attest to its effectiveness in 
front of my Alinco DJ-580T. No picture of this setup, but I can post it 
later.

I've also used a classic U310 (J310, MMBT310) design on 2m to great 
success. It's not the neatest layout[2], but it seems to work fine.

--- Zach
N0ZGO

[1] 
https://www.maximintegrated.com/en/design/technical-documents/app-notes/1/1759.html

[2] http://www.n0zgo.net/lna/