EME173 2M + 6M + 70CM PREAMPLIFIER KITS
 Saturday 21st January 2012

• KIT CONSTRUCTORS ALERT:
• EME173A70 KIT CONSTRUCTION NOTES:
• EME173A2 KIT CONSTRUCTION NOTES:
• EME173A6 KIT CONSTRUCTION NOTES:
• MOUNTING IN A DIECAST BOX
• EME173 TESTS
• SIMPLE BIAS TEE
• KIT FAULTS & MODIFICATIONS:Soon
• ORDER A PREAMPLIFIER KIT

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The EME173 Series Kits are low cost receive only preamplifier kits suitable for many Ham Radio applications to improve weak signals due to either high coaxial cable losses, or a low gain receiver. These Kits are particularly suited to being retro fitted into older Transceivers to improve the weak signal performance. Many commercially produced Transceiver & Receivers may have very low Noise figure Gas FET front ends, but generally lack enough gain in the receiver to comfortably listen to weaker narrow band signals like SSB or CW. The 70cm Preamplifier Kit is particularly suitable for improving 435MHz Satellite reception, & Amateur Television pictures. The 2M Preamplifier Kit can be tuned to be used at 137MHz for weather satellite use.

EME173A70 KIT CONSTRUCTORS ALERT

Pre June 2010 Prototype 70cm Kits only, there is a mistake on the PC board overlay for the mounting of one of the 10uF capacitors near the 78L08 regulator. the overlay diagram shows the +ve connection of the capacitor the wrong way around.

The above Images show how the coils are wound for the 70CM 430MHz version of the Kit. Take note of the winding direction of L2 & L3 especially so that they fit the board correctly. If you want to connect coaxial cable directly to the board, use good UHF construction practices as shown in the picture above.

The above Images show how the coils are wound for the 2M 145MHz version of the Kit. Take note of the winding direction of L1& L3 especially so that they fit the board correctly. If you want to connect coaxial cable directly to the board, use good UHF construction practices as shown in the picture above.

The above Images show how the coils are wound for the 6M 50MHz version of the Kit. Take note of the winding direction of L1 & L3 especially so that they fit the board correctly. If you want to connect coaxial cable directly to the board, use good UHF construction practices as shown in the picture above.

PARTS LIST 1 x ENCL01 Diecast 1590A Hammond 1 x SMA39 PC Board Female socket 1 x SMA12 PC Board Male 1 x SMA42 Fem-Fem Bulkhead Mount 1 x Extra SMA Nut & Washer

Mounting procedure.

• Cut out the two corners of the PC board using a nibbling tool.
• Solder an extended SMA socket with washer & nut ( SMA39 ), to the input of the PC board making sure that it is at right angles to the board. Take your time here to make sure that the sma connectors on both the input & output of the preamp are straight in both planes.
• Solder a SMA male PC board socket ( SMA12 ) to the output of the PC board making sure that it is at right angles to the board. This can be a bit more difficult to fit as it is a compromise as we could not get a male type with the same PC board mounting as the female socket.
• Mark & drill the two 6.5mm holes in the diecast box as shown in the picture above.
• Fit a extended SMA female to female bulkhead mount ( SMA42 ) through one end of the box & screw a nut & washer on only by couple threads to allow enough clearance to then get the preamp board into the box. Refer to the picture above on how two nuts & a washer are used to take up the clearance on the outside of the box.
• Slide the preamp board into the box & pass the extended input sma connector through the hole in the box, & lightly screw on the nut & washer to hold it into place.
• Lightly tightened up the output sma male to the sma bulkhead adaptor.
• Fabricate a small piece of brass shim as shown for the input sma connector to take up the slack due to the sloping sides of the box, & solder it to the top of the input sma socket as in the picture.
• Finally carefully tighten the input sma nut using a suitable sma spanner. Finally the nuts on the output sma bulkhead adaptor can be tightened ensuring that there is not excessive stress placed on the board & connectors.

EME173 PERFORMANCE TEST

RX ONLY BIAS TEE KITS

A Bias Tee Kit EME181 is now available that is suitable for powering the 6m to 23cm preamplifiers via a coaxial cable. The SWR return losses have been tested to be better than -20dB & losses less than 0.2dB. The Kit has only been designed for RX only use not TX.

KIT FAULTS & MODIFICATIONS EME173 KIT

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