RAT5 Manual version 1.2.0
RAT5 Information Manual version 1.2.0 © GW4GTE 2010
Page 12 of 29
The following is merely a recommendation for assembly order:
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Solder the IC sockets
for U1, U2 and U3. These will serve as landmarks to
assist component placement. Make sure the sockets are fitted the correct
way round. Support the sockets to keep them flush with the board when
soldering. At first only solder two diagonal pins then check for correct
alignment before continuing.
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Solder all the resistors
, ticking them off from the parts list as you proceed. If
any values are difficult to identify use a multi-meter to check. All resistors
have the same lead spacing on the PCB and all are mounted horizontally.
Bend the leads close to the resistor body by simply bending using a finger.
Gentle pressure should produce the correct lead spacing. Take care to align
the colour codes so that all resistors can be read in the same direction. Push
the leads through the PCB holes then bend the leads outwards slightly to
hold the part in place. Several resistors can be placed at a time in this way
then soldering done in batches. Snip the leads after soldering not before (this
reduces the thermal shock slightly and removes the risk of cutting the lead
too short before soldering)
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Solder all the ceramic capacitors,
ticking them off from the parts list as you
proceed. Little if any lead bending will be needed. Solder in batches if
preferred. Orient the capacitors such that the values are visible from the
same side.
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Solder Q1 VR1 and D1
taking care not to mix them up – they look similar.
Follow the case orientation shown on the PCB layout. The middle pin of Q1
may require bending depending on the type supplied.
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Solder D2
, 1N4148 making sure the band orientation matches the PCB
layout image.
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Solder FL1
. Take extra care not to overheat this component.
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Solder VC1
, ceramic trimmer applying extra solder onto the larger pads for
greater mechanical rigidity.
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Solder the electrolytic capacitors
, carefully observing the correct polarity.
The negative pin is adjacent to the side marked with a stripe down the side of
the plastic case insulation. Polarity is marked on the PCB layout.
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Solder the transformers T1, T2 and inductors L1 and L2
. Note they are all
the same component type. If the unused screen tabs haven’t been snipped
off already, snip off now, double checking you are snipping the correct one!
All four parts use the tab on the same side. Tin the earth tab before inserting
the coil into the PCB – this avoids overheating the PCB track should tinning
take a while to complete.
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Solder PL1, PL2, PL3 and PL4
. Snip the pin strip supplied if required. Note
PL3 can be left as a 10-pin strip. Snip pins flush to the PCB in unused
positions. SK3 can be left as a 10-pin connector. See Section 4.1 for
suggestions re connecting external leads.
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Solder RV1, RV2 and RV3
Note RV1 and RV2 are linear (marked B10k),
RV3 (volume) is logarithmic (marked A10k).
This completes the PCB soldering procedure. Next carry out the
continuity checks in section 3.1 below.
