3.5MHz
10W SSB transceiver
with 14 transistors by JF1OZL
In
every weekend, I go to the top of the mountain and make local expedition with
50MHz SSB. In week day , after job, I operate 7MHz CW on my shack. But in these
days, on the 7MHz , my signal skips out from Japan and I can not contact any
station after 10 o*clock. Therefore I decided to make 3.5MHz SSB and CW rigs.
I will show you my SSB rig on this page and I will show you CW one on the next
page. With each gears, I could contact about ten domestic stations.
Frequency planning
I have about five hundred*s of crystals on my junk box. On these crystals ,
I have some kind of groups that has the same named frequency. With the same
named crystals, I can construct rudder filters and carrier oscillator. On this
case I choose seven 9.50923MHz crystals. With six of them I made a filter. Band
width of it is adjusted for 2.5kHz by changing the capacitors, by cut and try
method. The frequency of the carrier oscillator is adjusted on the upper edge
of the pass band of the filter, by changing the capacitor on the gate of the
oscillator FET, with cut and try method. See the upper left side of the circuit
diagram! Pass band of the filter is from 9.5073 to 9.5107MHz. the carrier frequency
is 9.5093MHz. These experiment must be done before beginning to making the transceiver.
On this time I could get the prospect to make a 9.5093MHz LSB generator. On
the next step, I had to consider how I can convert this 9.5093MHz LSB signal
to 3.5MHz LSB signal. Yes I need 6MHz local oscillator. 9.5MHz LSB-6MHzCW=3.5MHzLSB.
But 6MHz VXO(variable crystal oscillator) can be changed it's frequency only
12kHz, because VXO can be changed it's frequency about 0.2% of it's oscillating
frequency. 6MHz*0.002=12kHz. In Japan , 3.5MHz SSB band is from 3.5025 to 3.5075MHz.
It*s band width is 50kHz. Therefore this VXO will be able to cover only a part
of the SSB band. I feel it is not good. In order to make big width VXO, I made
16.165MHz VXO. And I made another 10.615MHz crystal oscillator. And I got 6MHz
local signal by subtracting these two signals. And by changing oscillating frequency
of the OX, I can make two channel of signals. I will put these frequency planning
in order as follows.
"Fcar" is carrier frequency,9.5093MHz.
"Fxvo" is XVO frequency, from 16.6036 to 16.5862MHz.
"Fxo1" is first channel frequency, 10.61902.
"Fxo2" is second channel frequency, 10.64902.
Fout1=Fcer-(Fvxo-Fxo1)=3.5249 to 3.5723
Fout2=Fcer-(Fvxo-Fxo2)=3.5549 to 3.6023
Block diagram transmitting time
mic-->
af amp-->
DBM-
modulator-->
9.5M
Xtal filter-->
IF AMP-->
DBM-
convertor-->
3.5M BPF--->
RF-AMP
FR-AMP
LPF
ANT
9.5MHz-->
local OSC
upside connect
upside connect
upside connect
16MHZ
VXO
------->
DBM-
mixer------>
6MHz
BPF
Buffer
AMP--->
upside connect
10MHz
XO
------->
upside connect
receiving time
ANT-->
3.5M BPF--->
RF amp-->
RF amp-->
-->
DBM-
convertor-->
9.5M
Xtal filter-->
IF AMP-->
DBM-
modulator-->
af amp-->
head phone
upside connect
9.5MHz-->
local OSC
upside connect
upside connect
16MHZ
VXO
------->
DBM-
mixer------>
6MHz
BPF
Buffer
AMP--->
upside connect
10MHz
XO
------->
upside connect
Construction and typical point
1. Audio amplifier is a normal transformer input and output type push pull amplifier.
It is used as a microphone amplifier on it*s transmitting time. It is used as
a head phone amplifier on it*s receiving time. On the first side of the output
transformer, the six LED is connected. It limits the signal strength of the
microphone amplifier under 300mVc-p. In order to avoid distortion, audio signal
must be 10dB lower than the carrier signal.
2. On the receiving time , one stage of audio amplifier is pre located before
the push pull amplifier. It can offer the enough total gain of the receiver.
But when I put the capacitor on the emitter of the transistor this amplifier,
the total gain became too much , and my headphone was full of noises.
3. 120 micro henry of micro inductor is used on the souse of the FET of the
crystal oscillator. I got 1000 pieces of them on these days. Therefore I decided
to use it actively.
4. About crystal filter, please see another page of my home page! The filter
on this transceiver has 6dB ripple on it's pass band. But nobody talked about
my sound on the 3.5MHz SSB because 3.5MHz SSB band is full of noises.
5. In this machine three DBM( double balanced mixer) are used. All are made
with the same parts. 1S1588 switching diodes and FB801 tri-filer transformers
are used. 1S1588 is better than 1N60 on these purpose, because the character
of the silicon diodes are more uniform than germanium diodes. I measured the
carrier suppression of this modulator is better than 40dB.
6. About coils, you can see the name of OZL series and FCZ series. FCZ series
are the mane of the coils made and sold by JH1FCZ. OZL series are the name of
the coils made by myself imitating the FCZ coils. They are not sold in anywhere
in the world. But you can imitate by yourself and you can use in your original
gears. Please see how to make them on the another page of my home page.
7. T8 is output transformer of the final radio frequency amplifier. T8 is made
with four FB801 ferrite beads and 0.2mm diameter poli-uletanne (enamel) wire.
First side of it is winded by one turn. Second side of it is winded with two
turns.
8. Idle current of the final amplifier is 0.3A. In a moment of maximum power
output, the currect of it becomes 2A. Then the power of it becomes 2A*20V=40W.
The RF maximum power is 10W. Therefore the final efficiency is 20%. For our
amateurs, that(=20%) is normal numbers. Because input power of the final amplifier
is 40W, I needed very big heat sink. The size of it must be twice bigger than
my perms.
9. Low pass filter after final amplifier is constructed with single pei filter.
The coil of it is winded around the 8mm diameter core bobbin with 0.2mm enamel
wire. Only with this simple filter, I did not watch any TVI on my TV. I felt
3.5MHz is far from TV frequency.
10. Push pull wide band amplifier is used as a driver of the converter. It has
reason. The IF signal on the IF port of the converter DBM becomes 700mVc-p.
Therefore the local oscillator signal must be bigger than 2 volts, to avoid
any distortion on this stage. Therefore I used such a high power amplifier on
this stage. Unless this office, some unwanted signal occurs on convertor DBM
and it will happens some TVI or distortion of your voice signals.
11. I used 1.5D2V slim coxial cables to connect relays and circuits, to avoid
unwanted self oscillation.
12. I like relays. I don't like diode switch. But to change the crystal of the
oscillator in this machine , I used a diode switch. In this case it works good.
13. I used many 2SC1815 named transistors. It was got by 7 yens per piece. Yes
it is very cheap. But I feel this transistor is almighty on lower HF small signals.
But only on oscillator, I feel the FET has better activity.
14. You can see, the case is very big. It is second use of my uncompleted FM
transceiver. In Japan we have the proverb that bigger is better than too small.
15. In this machine, it has three oscillators on it. Each load of them are not
changed from transmitting time to receiving time. Therefore the oscillated frequencies
are not changed on it's transmitting time and receiving time. It is very good
point of this construction.
16. In this machine , all small circuits are working as common of transmitter
and receiver. Therefore the useful 10W SSB transceiver is constructed with only
14 transistors. But this type of construction needs many relays. I used cheap
24 volt relays with 20 volt power voltage from my regulated power supply.
17. The Vcc of final is also driven with this 20 volt. Another circuits are
supplied 12 volts by the three legs regulator(7812).
18. I could make contact with all site of Japan by this simple 14 transistor
machine.
19. One time I completed this gear unless the final amplifier. In that timing,
the output power of this transceiver was 100mW. But I could not make any contact
with this machine. I feel the environmental noise will be bigger than my signal
in Japan. In Japan the population is very big. And we use many electric instruments
on the night. The many electric instruments make many noises. It may be different
in your country. You may use this gear without of final amplifier.
20. I bought a pair of 19 meter long vinyl coated wires. I made a dipole antenna
with them. I set up it around my house very closely on the wall of my wooden
house with bent in some points. Yes it is called bent dipole. I can not buy
the 40 meter long garden , because I am only an employee of machine company.
Full size dipole can be used only farmer or president of the company in Japan.
HIHI
21. From many hand builder living in abroad, untill now, I received many request
to teach them the character of the transistors used on my home page. Therefore
I will show you them below.
In
every weekend, I go to the top of the mountain and make local expedition with
50MHz SSB. In week day , after job, I operate 7MHz CW on my shack. But in these
days, on the 7MHz , my signal skips out from Japan and I can not contact any
station after 10 o*clock. Therefore I decided to make 3.5MHz SSB and CW rigs.
I will show you my SSB rig on this page and I will show you CW one on the next
page. With each gears, I could contact about ten domestic stations.
