13/23CM PREAMP EME103B KIT
Saturday 31st December 2011

 

The EME103 is a general purpose preamplifier kit suitable for use between 1200 & 2500MHz. The design uses a low noise NEC NE3210S01 HJ FET & MMIC second stage. The Kit is easy to construct & no tuning is required to achieve the advertised performance.

PLEASE NOTE: THAT THE EME103B KITS HAVE BEEN DISCONTINUED & REPLACED BY THE NEW EME179A SERIES KITS.

Spare Parts are readily available for this Kit.

 


EME103B KITD SHOWN

 

 

 

 

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EME103B KIT CONSTRUCTORS ALERT

This applies to all Kits sold after October 2010. Due to the Mitsubishi MGF1302 no longer being manufactured, we have decided to change the device to a more modern PHEMT device that are mass produced. Kits late September 2010 onwards are now being supplied with the NEC NE3210S01 HJ FET & some minor changes have been made to the active bias circuit. The 150ohm resistor has changed to a 220ohm, & the 2k7 resistor has changed to a 1.2k. No other changes are needed & performance is the same. No attempt has been made to re tune the input circuit for a better noise figure.

KIT CONSTRUCTION NOTES

 

The Picture Left shows how the NE3210S01 is mounted. L1 is bent so that it can be soldered to the Gate lead. The Picture left shows a new prototype version for 1200MHz using 3.5 turns of 0.315mm ECW on a 2.5mm drill bit. A 47nH 1008 coil has also been used on the output to feed DC to the NE3210S01.
       

 

KIT CHANGES & MODIFICATIONS

1/ This applies to all Kits between January & June 2008. A number of constructors have reported that the voltages around the MGF1302 GasFET have been incorrect. Some have found the BC857 transistor to be faulty. We have in fact found that the complete batch of BC857 Transistors supplied to us in December were in fact 6.2 volt Zener diodes. Please email us if you have the problem & we will post a replacement BC857 transistor to you.

2/ Any instability problems are usually caused by the RF connections in & out of the board. Connectors that are suitable are listed in the Kit notes. Boxes can also cause instability as they can act like Microwave Waveguides. Boxes that are close to a Waveguide size for 1200 to 2400MHz should be avoided.

3/ This applies to all Kits sold before October 2010. Due to the Mitsubishi MGF1302 no longer being manufactured we have decided to change the device to a more modern PHEMT device that are mass produced. Kits late September onwards are now being supplied with the NEC NE3210S01 HJ FET & some minor changes have been made to the active bias circuit. The 150ohm resistor has changed to a 220ohm, & the 2k7 resistor has changed to a 1.2k. No other changes are needed & performance is the same. No attempt has been made to retune the input circuit for a better noise figure. See the picture above that shows a replacement 3.5 turn inductor for 1200MHz. Initial tests indicate a much lower NF, & a gain of over 36dB on the dual stage version.

 

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