Topband: Preamp in MFJ1026

Tom Rauch W8JI@contesting.com
Sun, 7 Nov 1999 07:52:13 -0500


> 1026 jumper set for maximum gain for the auxiliary antenna (Beverage).  It
> makes a significant improvement in the signal level there compared to it
> being switched off. 

While the pre-amp will work in some cases, it is primarily designed 
for low signal-level noise sensing (small whip or loop) antennas. I 
certainly don't recommend buying a 1026 just to get its amplifier, 
especially if you plan on using the 1026 on a large antenna. 

It's best to avoid poor dynamic range, harmonic distortion, and IMD 
performance devices (like low signal level single-ended FET's or 
MMIC devices) in pre-amplifiers. I've found MMIC's especially bad 
for distortion products. They trade off performance for circuit 
simplicity.

The 1025/26 is designed to be a zero-gain device. All amplification 
should be ahead of the 1025/26, and hopefully be pass-band 
filtered and use good CATV-type bipolar transistors.
73, Tom W8JI
w8ji@contesting.com



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