Hardware |
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2m-40m
PORTABLE ANTENNA FOR FT 817
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This antenna is made by 3 parts: 1mt long telescopic whip,
50cm long coil for 10-40m, 50cm long common part fitted by a
PL259 connector; when fully telescoped it is 1.95mt long approx The common part works like 1/4 lambda antenna for 144 MHz.
The common part + the telescopic whip work like 1/4 lambda for 50 MHz.
The common part + coil + telescopic whip work on 10-12-15-17-20-40 m, band
changing is achieved by putting the plug into the appropriate socket on
the coil and fine tuning adjustments are made using the telescopic whip.
You can fit the antenna on a magnet mount and put it on a car or another metal surface or fit
it directly on the antenna jack of the
transceivers using three or four 4m-long wire as ground plane
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construction details of the antenna (PDF)
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construction detail of the coil (PDF)
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SOME
DETAILS OF MY ELEVATION SYSTEM
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A TX/RX SEQUENCER FOR PA &
PRE SWITCHING |
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download schematic diagram |
get
Acrobat Reader free |
The advantage of sequencing is to protect equipment from
damage. If RF
power is applied before TR relay is not fully closed it can arc contacts on
relays and RF can leak into the preamplifier and destroy it. The sequencer
described above allows going into trasmit and going back to receive from trasmit
with a delay of 0,20 seconds, eliminating the problems just described. With one
side of the circuit you can drive antenna relays and preamplifier, with the
second side you can drive PTT control of your PA. Jumper allows to set the
outputs to ground or 12v.
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UNIVERSAL INTERFACE BETWEEN PC SOUNDCARD
& COM PORT AND TRANSCEIVER
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I use this interface to run 9a4gl Meteor
Scatter, WinPSK, AGW packet and all
other applications with transceiver and Sound Blaster. At the moment I run with
an ICOM IC821h and an ICOM IC706mk 1 and so I use the rear accessories socket of
these transceivers to/from PC sound card. I've used the transformers to
eliminate noise and ground-loop between PC and RTX. On my circuit I put SMLP5001
SMD transformer but any 1:1 600 ohm transformer is ok.
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Because some programs use DTR and others use
RTS, i've used both
to make a general pourpose PTT interface. To achive a high voltage isolation
between COM ports and external world I've deciced to use Toshiba MosFet
photocoupler TLP595G (you know, to repair a PC motherboard is very expensive
!!!).
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Here are the pins on the com port:
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DB25 |
DB9 |
Name |
Description |
In/Out |
1 |
- |
- |
Chassis Ground |
- |
2 |
3 |
TX |
Transmit Data |
Out |
3 |
2
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RX |
Receive Data |
In |
4 |
7 |
RTS |
Request to Send |
Out |
5 |
8 |
CTS |
Clear to Send |
In |
6 |
6 |
DSR |
Data Set Ready |
In |
7 |
5 |
SG |
Signal Ground |
- |
8 |
1 |
DCD |
Data Carrier Detect |
In |
20 |
4 |
DTR |
Data Terminal Ready |
Out |
22 |
9 |
RI |
Ring Indicator |
In |
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