EME72B

EME72B 23CM TRANSVERTER KIT
Thursday 5th June 08

KIT CONSTRUCTORS ALERT:
KIT CONSTRUCTION NOTES:
KIT FAULTS & MODIFICATIONS:
PROTOTYPE TESTS:

EME72B KIT CONSTRUCTORS ALERT

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.

CONSTRUCTION IMAGES OF THE EME72B PROTOTYPE KIT

The above image shows how the components are soldered to the EME72B board. A 25mm wide Tinplate strip is soldered around the board to make it easy to mount the SMA09 connectors. The 4 x mounting lugs on the SMA09 connectors are broken off with a pair of pliars, & then the backs are filed flat & soldered to the Tinplate box.

The Transverter above uses 2 x Hammond 1444-12 Aluminium Chassis Boxes ( 178x127x51mm ) Bolted together. The front panel ( 127x101mm ) was cut from 1mm Aluminium sheet. The heatsink & fan was a surplus 12 volt unit from a PC.

PARTS LIST 1.

1 x Power Switch ( FARNELL )
1 x Green LED 5mm ( LED 6 )
1 x Red LED 5mm ( LED 1 )
2 x LED Bezels 5mm ( LED HOLDER )
1 x RCA Socket Black ( RS01 )
1 x BNC Socket Suit RG316 ( BNS04 )
1 x N Socket Suit RG316 ( NS06 )

1 x 2 Pin Socket DC Power ( SOCKET 1-2 )
1 x 2 Pin Microphone Plug ( PLUG 1-2 )
1 x Fuse Holder 2AG ( FUSE HOLDER2 )
1 x Fuse 10A 2AG SB ( FUSE 10A2AGSB )
2 x Metres DC Power Cable 10A ( CABLE3 )
1 x Heatsink & Fan PC Type
2 x Hammond 1444-12 Chassis ( RS )
2 x Hammond 1434-12 Covers ( RS )
1 x Front Aluminium Panel

PARTS LIST 2.

1 x 23cm Transverter Kit ( EME72B KIT )
1 x 500MHz Local Oscillator Kit ( EME65 KIT1 )
1 x 96.000MHz TS07S Crystal ( 96.000MHz )
1 x 50degree Crystal Heater ( 50DegC )
1 x 20W PA ( RA18H1213G KIT2 )
1 x Relay Kit ( EME144 KIT )
1 x Transverter Sequencer Kit ( EME66 KIT )
1 x 14 x 10mm Metal Spacers ( SPACER03 )
6 x SMA Sockets PCB Mt ( SMA09 )

9 x Right Angle SMA Plugs ( SMA16 )
2 x ft RG316 Cable ( RG316 )
36 x Bolt Panhead M3x6mm ( BOLT04 )
20 x M3 Star Washer ( WASHER01 )
8 x M3 Nut ( NUT01 )
1 x 300x25mm Tinplate Strip
2 x Grommet 9.5mm ( GROMMET 1 )
1 x Grommet 12.5mm ( GROMMET 2 )

BELOW SHOWS THE TESTED RESULTS OF THE PROTOTYPE KITS

KIT FAULTS & 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. The Transistor should have a 3H marking on the case. Please email us if you have the problem & we will post a replacement BC857 transistor to you.

2/ Instability of the MGF1302 or receiver taking off. This is due to a problem on the Local Oscillator input to the ERA3 Amplifier. A small square piece of absorb foam can be placed on the circuit board between the preamplifier section & the ERA3 multiplier shown below. I think its a 50ohm mismatch problem but these are difficult problems to fix.

3/ A number of constructors have had to replace the ADE11X mixer. I am still unsure if it is due to manufacturing problems or if it has been overheated when it is soldered to the board. Symptoms are low TX output & low gain receiver.

4/ The TX output from the EME72 is not really enough to drive a RA18H1213G module to full power, ( 20 Watts ). Recent tests on the RA18H1213G modules gain has been around 23dB, where as earlier batches we were getting 27dB, but I am unsure if Mitsubishi has changed the modules internally. Along with this the EME72 has lost some gain in current transverters which may be due to extra losses in the mixer & gain stages that only allows around +10dBm output compared to around +13dBm on older Kits. So total loss could be around 7dB with current Kits. Mini-Kits is working on a new 1 Watt driver amplifier to resolve this issue.

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