Basic EME103 23cm Preamplifier Kit
PLEASE NOTE: That this Product has been discontinued, but spare parts
are readily available from Mini-Kits
Please Note: that all information including pictures on this web page are copyright to Mini-Kits and must not be used on any other web site, or reproduced in any publication.
EME103 Kit Description:
The EME103 Kit was one of the most popular Kits that we ever sold. The first verson of this Kit was produced in the mid 1990's and continued until around March 2011. The preamp used the Mitsubishi MGF1302 GasFET and was able to be used with minor changes on both the 13 and 23cm bands. There were a few changes in late Kits around 2010 due to the MGF1302 becoming obsolete, so the Kit was then sold with the NEC NE3210S01 and some small improvements were made to the input inductor.
For a complete description of the Kit before it was discontined please download the Complete EME103 KIT Notes
EME103 Kit Construction Notes:
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 Changes and Modifications
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 and some minor changes have been made to the active bias circuit. The 150ohm resistor has changed to a 220ohm, and the 2k7 resistor has changed to a 1.2k. No other changes are needed and performance is the same. No attempt has been made to retune the input circuit for a better noise figure.
This applies to all Kits using the NE3210S01.
Please note that the input inductor hoop L1 used in early Kits has now been changed to a 3.5 turn coil. This provides a better match the input of the HEMT and lowers the noise figure.
Fitting of the input inductor L1 for a NE3210S01
L1 changed in later Kits to 3.5 turns of 0.315mm ECW on a 2.5mm drill bit spaced 1.5 turns.
3/ 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 and out of the board.
Only connectors like SMA can be used & have to be soldered very directly to the board. Mounting the PC board inside an enclosure
can also cause instability as they can act like Microwave Waveguides.
Enclosure sizes that are close to a Waveguide size for 1200 to 2400MHz should