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G8MNY > TECH 27.09.10 06:53l 107 Lines 4638 Bytes #999 (0) @ WW
BID : 62801_GB7CIP
Read: GUEST
Subj: Palstar AT1500CV ATU
Path: IZ3LSV<IK2XDE<DB0RES<OE6XPE<UA6ADV<GB7CIP
Sent: 100926/2315Z @:GB7CIP.#32.GBR.EU #:62801 [Caterham] $:62801_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (Updated Aug 10)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ ³/~~~\³ ø ø Þ ³ Balun transformer for Balanced output.
³ ³__ __³ /~~\ /~~\ ....... ³ Direct Coax 1 & 2 & Bypass output.
³ ÀÄÄÄÄÄÙ | () | | () | : ø\o: ³ Tuned Coax 1 & 2 & Wire output.
³ ::Ü:: \__/ \__/ : : ³ 300W & 3kW cross needle power meter.
³ '' '' :.....: ³ ATU is T arrangement C L C using
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ large flat strip roller coaster inductor.
Unfortunately this large 1500W QRO ATU flashed over & caught fire, due to poor
design of the roller coaster coil mounting brackets, flammable construction
fibre board & inexperienced user (me) when tuning up with only 400 Watts.
_ _ INTERNAL LAYOUT SIMPLIFIED CIRCUIT
ÚÁÄÁÂÄÁÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³ S ³ v Fire ³ Direct Via
³ W ³ ÜÜÜÜÜÜÜÜܳ o Thu ATU
³ R ³ C1 C2 Þðððððððݳ TxÄSWRÄ>o Coax1 o<ÄÄ¿
³~~~ ======= ======= Þðð L ððݳ o Coax2 o ³
³ ======= ======= Þðððððððݳ Wire o ³
³ SW ======= ======= Þðððððððݳ Via o¿ ³
³ ÜÜÜ ======= ======= Þðððððððݳ ³ HOT ³
³ º ======= ======= Þðððððððݳ ATU ÀÄ´ÃÄÄÂÄÄ´ÃÄÄÙ
³ º ======= ======= Þðððððððݳ C1 ³ C2
³ º ======= ======= ßßßßßßßßß³ L<¿
³ º º º º ³ ³ ³
ÀÄÄ×ÄÄÄÄÄÄ×ÄÄÄÄÄÄÄ×ÄÄÄÄÄÄÄÄ×ÄÄÄÄÙ ÄÄÄÄÄÄÄÄÄÄÄÄÁÄÁÄÄÄÄÂÄÄÄÄÄ
ßßß ßßßßß ßßßßß ßßßÝ ///
On the lower 2 back coil insulator combs, there are 2 right angle brackets that
have sharp corners mounted only a few mm away from earth & the RF HOT top of
the tuned circuit high voltage point. They are mounted on inflammable thick
fibre board.
ROLLER COASTER
Flammable³ ³ RF³³³³³³³³³³³Silver Plated
Fibre ³ ³ HOT³³³³³³³³³³³Flat Coil Spiral
Board ³ ³ END³³³³³³³³³³³
³ ÃÄÄÄÄÁÁÁÁÁÁÁÁÁÁÁFlammable
"L" ³ ³_ø_ø___________Support
Bracket ³ ÇÄÄÄÄÂÂÂÂÂÂÂÂÂÂÂ Combs
Screws (³ º] ^Sparks
³ º___/ Jump Earth
ÄÄÄÄÄÄÄÄÄÁÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄChassis
The Caps C1 & C2 are designed for very high voltage & should be the first thing
that arcs over not these brackets!
REPAIR.
The burnt fibre board & shaped mounting comb strip must be cleaned of any
charred material with a sharp knife. This may mean removal & disassemble of the
roller coaster.
MODIFICATION
To stop reoccurrence of the RF flashover, the 2 RF hot end "L" shaped brackets
were cut down in length & 1 nut & bolt left out of each.
__ ___ __ __ __
Screw³ ³ \shortened
holes
³ ORIGINAL ³ MODIFIED
Doing this mod, adds about 1cm to the flashover arc distance! And has no effect
on the sturdiness of the roller coaster assembly.
LOOSE SCREWS
As this unit has been used for /P work, some screw had soon rattled lose,
despite locking washer nuts! These have been tightened up & threads painted.
IN USE
I use it for /P demonstration stations with a DRAKE L-4B PA & IC735 exciter.
_________ptt+ALC
______ ___ _____ ³ ___ ³ _________ ______
³ ôISOÃ--´IC735ÃÄÙ ³ATU³ À´DRAKE PA ÃÄ´ HF ³_ oÄ>1kW Dummy Load
³Laptopô___³Ú-´12V ÃÄÄÄÄÄ´ ÃÄÄ´_________³ ³Filter³ \oÄ¿ _____
~~~~~~ mic³_____ÃÄÄ¿ ³ ³ ³DRAKE PSU³ ~~~~~~ ³ ³ QRO ÃÄ>80m Dipole
BatteryÄÄÄ´PSU55³ _³_ ³___ÃÄ¿ ~~~~~~~~~ ³_³1.5kWÃÄ>40m Dipole
~~~~~ ³BHI³ _³_ Topband 160m ³ ATU ÃÄ>3el Beam
HeadphonesÄÄ´LS ³ /// long wire aerial ³_____ÆÍ>G5RV
~~~
The small ATU after the Rig selects can select an internal dummy load or the
long wire. On WARC bands it is used to tune out the DRAKE linear bad SWR of its
out of tune input matching circuits, the output matches easily.
The HF filter is sometimes used to make sure there are no VHF harmonics, if
station is in a sensitive RF area & direct not ATU aerials are possible. With
the G5RV then the ATU's balanced output is used.
For public demos, a RF proof AF PA is used with mic audio from the AUX socket
of the IC735 & BHI noise reducing LS system, so that both sides of the QSO can
be clearly heard.
See also my Tech buls "HF ATU & SWR Bridge VC300LP/QT-1" & "Drake WH7 QRO HF
SWR Bridge".
Why don't U send an interesting bul?
73 De John, G8MNY @ GB7CIP
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