Hi Jan,
Am 26.05.2012 10:21, schrieb pa3abk:
On 26-5-2012 0:48, Stefan Schäfer wrote:
I've been thinking about using the 2nd D Flipflop of the 4013 and
build a divide by 4 circuit. With this exciter one could easily use a
HF TRX like the IC-706 and drive the exciter by transmitting QRP in
the 160m band. 1900 kHz will then result in 475 kHz and the frequency
accuracy should be fine. In Split-mode one could transmit on 160m and
receive directly on MF. Using 3x 150 Ohm / 2W in parallel and another
1 kOhm resistor in series with 2 antiserial Z-diodes should be OK for
driving the input of the 4013 and getting a perfect SWR for the
TRX... Maybe this is how i will do it.
A similar set-up is running for some time here.
I started with de QTX 100W design with a 2MHz x-tal driven. (I'm also
one of those lurkers of this group)
Frustrated by the single channel I realized thet the TS-440 has an
"all band" option.
Simply replaced the the X-tal with a "dummy"-driven single transitor
in saturation, which fed de CD4024 by 4 divider.
From the dummy there is an attentuation by 4. Drive from the TS440 is
full CCW, almost zero.
It produces100W from 400-600kHz. Off course only non-lineair modes
can be used (CW, Opera, Slowhell ect)
There is small interface which plugs into the transverteroutlet which
drive the fast reed antenna relais.
Yes, the relais, this is what i am doing in all my HF PAs as well. I
have a RX/TX relais that is bypassing the PA in RX mode. It is switched
automatically, detecting a input signal on the right band (using a small
band pass filter) and then switching to TX. It is fast enough so that a
"dit" in CW at 120 BPM can still be detected. So, it is quasi full-BK
mode. A delay time for releasing the relais can be adjusted by a pot.
Also experimented with a mixer from 2MHz to 500kHz which works fine,
only it requires some caution in relation to the drive.
A mixer for receiving? How do you receive on MF? I still have no
concept. Of course there are many but i have no decision so far. Yes, a
simple DC receiver is my favirite as well. The IC-706 is an option but
not quite /p (takes 1.5A in RX mode!). My K2 doesn't work there i am
afraid. So i will need a converter.
The LPF in my PA actually is a BPF so i will have it in series to the
RX. That will be a very good first preselector...
Otherwise a wide noiseskirt is included. The PA is not lineair and
whole circuit has a certain "treshold".
NL 600m license is restricted to CW only, we consider Opera when
prefixed with a morse ID a such, the rest which follows is just test
and tune signals :-)
The divider route is therefore best suitable in my case.
Jan/pa3abk
OK, Jan, hope to meet you on that new band, hopefully this year.
73, Stefan/DK7FC
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