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Peter Miles
Northam, Western Australia
QRZ Page: VK6YSF
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TRANSMITTER CONVERTER
FOR 630M BAND
630m band (472kHz-479kHz) Transmitter
Converter and common Low Pass Filter.
Under
development
HOME > PROJECT
> 630M
TRANSVERTER
>
The
transmit converter consists of four main elements, input attenuator to
reduce the RF power from the HF Tranciever down to a manageable level
for mixing,
ring mixer to mix the 10MHz LO (local Oscillator) with the transceiver
RF and produce a linear output within the 630m band (472kHz-479kHz), amplification
to raise the output from the ring mixer to a suitable level and
finally the low pass filter to reduce unwanted harmonics to a
satisfactory level for transmission.
Fig 1
Schematic of the
transmit stage including the input attenuator, mixer, amplification
and low pass filter. This circuit is
subject to further development.
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IF
Transmitter
RF PWR in Watts
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R1
Details
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R2
Details
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Required
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Derived
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0.5
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50 Ohm
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5 x 270R 0.5W Paralleled
= 54 Ohms
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470 Ohm 0.25W
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1.0
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50 Ohm
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5 x 270R 0.5W Paralleled
= 54 Ohms
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680 Ohm 0.25W
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2.0
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50 Ohm
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11 x 560R
0.5W Paralleled = 51
Ohms
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1k Ohm 0.25W
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3.0
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50 Ohm
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11 x 560R 0.5W Paralleled
= 51 Ohms
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1.8k Ohm 0.25W
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5.0
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50 Ohm
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11 x 560R 1.0W Paralleled
= 51 Ohms
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2.2k Ohm 0.25W
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Table
1 Attenuation network for various power levels.
Component
details
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TUF-1+
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Frequency
Mixers Module - TUF-1+
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Q1
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Transistor
- 2N3904
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Q2
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Transistor - IRF510
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C1
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Capacitor
- 10n 3kV
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C2
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Capacitor
- 10n 50V
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C3
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Capacitor - 470n 50V
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C4
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Capacitor - 470n 50V
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C5
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Capacitor
- Electrolytic - 47µF 50v
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C6
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Capacitor - 470n 50V
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C7
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Capacitor
- 10n 3kV
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C8
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Capacitor
- 4n7 3kV
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C9
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Capacitor
- 10n 3kV
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FB
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Ferrite Bead
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R1
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Resistor Carbon - 560R
0.5W x 11, See attenuation network
table
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R2
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Resistor Carbon - 1k
0.25W, See attenuation network
table
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R3
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Resistor Carbon - 68R
1W
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R4
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Resistor
Carbon - 6k8 0.25W
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R5
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Resistor
Carbon - 470R 0.5W
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R6
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Resistor Carbon - 27R
1W
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L1
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Single layer, close
wound air inductor, 5.9uH, 24turns on a 20mm former. See
air inductor design
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L2
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Single layer, close
wound air inductor, 5.9uH, 24turns on a 20mm former. See
air inductor design
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Photo 1 Assembled
transmit converter.
TOP
OF PAGE
Page
last revised 12 March 2022
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Space Weather
https://www.swpc.noaa.gov/
Notice Board
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VK6YSF JS8Call and
Olivia 8/250 operations.
Current activity is generally
focused - though not restricted to - JS8Call operations on the 20m, 30m, and 40m bands.
Currently
there is a particular emphasis on JS8Call on the 10 and 12 m band between 00:00 and 12:00 Z, often extending beyond this period.
Olivia 8/250 is used occasionally on the 20m band.
Proposed
band and mode activity
is often communicated on HamSpots: https://hamspots.net/js8/
or my profile on
X: https://x.com/vk6ysf97230
.
Feel free to contact me to discuss or arrange a schedule for a contact.
Post
date: 7 December 2025
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Western Australian SSTV net
Popular
Western Australian SSTV net for both digital and anolog SSTV.
Generally
found at 7214.0kHz LSB every afternoon from 08:00 UTC (4:00pm WST)
For more
details: https://www.wasstv.net/wasstv.net/index.html
Post
date: 8 December 2025
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VK6MJM LF (136kHz) and MF (474kHz) Beacon
VK6MJM is a LF/MF station
located in Manjimup, Western Australia.
Common Mode: FST4W 300 (Similar to WSPR)
Note:
other modes and sub-modes may be used.
Station details were presented by
Peter Hall (VK6HP) at PerthTech 2024.Presentation PDF: Peter
Hall VK6HP at PerthTech
QRZ Page: VK6MJM
on QRZ.com
Post
date: 10 March 2025
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