| MITSUBISHI
SERVICE BULLETINS
Conclusion
of Substrate Crack Page
1-2
Conclusion of Substrate Crack Page
3-14
ROHS Compliance for RA
& RD Series Modules
Application Note Thermal Compound AN-GEN-001
Application Note Application Thermal Compound AN-GEN-042
Application Note Application Thermal Compound AN-GEN-042-C
 Jan 2010
KIT
CONSTRUCTORS ALERT
The
EME76 PC board has been replaced with the EME176 in February 2010.
The boards are essentially the same except for the addition of
an optional attenuator on the input, & some changes to the
track layout to allow for TX switching of the Bias.
All
Previous Kit Notes have been replaced in February 2010 with the
following changes. Mini-Kits no longer recommends sanding the
Mitsubishi HS2 packaged modules flat, & now only recommends
following Mitsubishi's recommendations as per their application
Note: AN-GEN-042C. If you have
been supplied with Kit notes that recommends sanding the module,
then please disregard this & do not modify or sand the module
in any way. Please read Mitsubishi's service bulletin AN-GEN-042C
& follow their procedure.
RA08H1317M
KIT
 |
 |
Pictures
show how the low pass filter inductors are wound & mounted
on the board. Take note of the coil winding direction &
how they are mounted above the board. The pictures also
show how RFC1 is wound & mounted. The picture shows
2 turns but can be 2 to 3 turns & is not critical.
Pictures
& RF design shown is copyright Mini-Kits |
|
RA07H4047M
KIT
 |
 |
Pictures
show how the low pass filter inductors are wound & mounted
on the board. Take note of the coil winding direction &
how they are mounted above the board. The pictures also
show how RFC1 is wound & mounted. The picture shows
2 turns but can be 2 to 3 turns & is not critical.
Pictures
& RF design shown is copyright Mini-Kits |
|
RA30/60H1317M
KIT
Both
of the VHF RA30 & RA60H1317M modules require the use of a
suitable Low Pass Filter to reduce the -25dBc second harmonic
to a suitable level that complies with current ACMA & FCC
rules of at least -50dBc.
The
filter can be built on some scrap PC board, or you could make
a simple board. I used a board that I had surplus from an old
project, which saved time with building the filter. The main points
to remember is that the two Pi filters need to be shielded from
each other, & isolation can be further improved if both coils
are mounted 90 degrees to each other. The 170nH coils are 8.5
turns of 0.8mm ECW wound on a 6mm drill bit, & stretched to
a length of around 10mm. Mount the coils 1 to 2mm above the top
of the PC board. Use good quality 27pF 500v Mica & 10pF ceramic
trimmers capacitors. CX 1pF is made using a length of RG316 cable.
RG316 is slightly less than 1pF capacitance per 10mm length, so
cut it for a length of around 12mm long after soldering the connections
to the board. The shield is 10mm high minimum. & made using
some scrap brass or tinplate strip. A cut out needs to be made
so that it clears the strip line on the top of the board. The
filter is simply tuned by using a low powered transmitter into
a VHF power meter for maximum RF output.
 |
All
Components are available from Mini-Kits |
| PARTS
LIST:
2x 27pF
500v Mica RF
2x 10pF Ceramic Trimmer
|
1x
30mm length of RG316
1x 50cm length of 0.8mm Enameled Copper Wire
1x length of 10mm wide thin brass or tinplate strip |
KIT
FAULTS & MODIFICATIONS PRE FEBRUARY 2010 ( EME76
PC BOARD KITS )
1/
This applies to all RA series Module Kits.
The recommended mounting of the Mitsubishi HS2 packaged modules
has now changed to the recommended mounting procedure supplied
by Mitsubishi in service bulletin AN-GEN-042-C.
Modules should no longer be sanded flat
due to the possible damage that can be caused if they are over
heated. A very flat heatsink that has a very smooth surface with
no scatches is required to mount the module. Mini-Kits recommends
the use of a Pentium P4 fan assisted heatsink that will dissipate
up to 100 Watts heat for all modules under 30 Watts output, &
as low as 20% efficiency. These can be found on old Pentium mother
boards in computer recycling shops.
2/
To use the Amplifier with a Sequencer like the EME66, it is suggested
that the board is modified to switch 12 volts to the input of
the 5v regulator. The PC board track between the 0.1uF capacitor
& 100uF capacitor needs to be cut with a scalpel to disconnect
the main 12 volt power from the regulator. The RA series modules
being MosFET types, can be connected to 12 volts permanently,
& the bias switched to turn it on & off. The delay 3 output
from the EME66 sequencer is connected to the input of the 5v regulator.
3/
If the PA is mounted in a shielded metal box then the feed through
capacitor that is normally soldered on the board can be soldered
in a hole in the side of the box to feed the main power through
to the board. Another feed through could also be used if you are
switching the bias supply.
4/
An Email from Wolfgang, DK1OV and Heinz, DJ2IV on problems &
repair of the RA18H1213G modules.
We
want to inform you about our project 23-cm PA with the modules,
which we got from you. We built two amplifiers, each with two
modules in parallel. We mounted the modules onto a 5mm thick piece
of copper with the dimensions 100 x 160 mm (about 4 x 6.5 inch)
and this onto a big aluminum cooler. This was a lot of work but
we did it because you told me to be careful with too much power
output due to thermal stress. The amplifier worked perfect first
and we got 80 W output at 12,5 V supply. But after a few minutes
the power dropped to less than a half, one of the modules failed.
The quiescent current was 2 A at the failed module the other module
draws 3.5 A. We opened the failed module and found, that the first
two FET's didn't get drain-voltage. The supply-line was interrupted
near to a blocking-C, in one of the modules the most right one,
in the other module in the middle. After we soldered a thin copper
wire along the supply-line, the modules worked well again and
we had no longer problems until now. We tested the amplifiers
for hours with maximum output. The maximum power output is more
than 80 W at 12.5 V, it drops to 75 W when the amplifier gets
warm and remains constant then. In DATV we get about 20 W linear
output with 35 dB inter modulation suppression. We are very satisfied
with the result.
KIT
FAULTS & MODIFICATIONS POST FEBRUARY 2010 ( EME176
PC BOARD KITS )
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Thursday
22nd April 2010
