Monday, October 13, 2014

474.200 kHz / 630m WSPR

Receive only FTTB.  using the (UN)Flex1500  the Flex1500 will TX at 471-479 kHz but outputs a  very distorted signal below 481kHz
antenna  loop  or 160m inverted L tuning at base.

last year used a QTX switching mode 50W pa behind the Flex1500 good result
I do not believe Flexradio is going to change the firmware to include 471-479 HAM allocation.
They are not as flexible as the name would indicate.. Fixradio would fit more.

0dBm  XVTR signal  below 481kHz
http://pa0o-jaap.blogspot.nl/2012/12/flex1500-xvtr-output-below-481khz.html



L/C tunes 1:1.0  but very selective  needs a remote tuning motor









Power SDR screen covering 473.5 to 476.5kHz  the vertical white ruler is the 200Hz WSPR window
very close to the strong French speaking AM broadcast signal sidebands.
at 474.582 Hz    a mirror  ? the MW starts from 512kHz   LW ends at 300kHz


At our latest  radio market in Eelde  I found this  high power mediumwave VAriometer brand new ?professional piece of equipment   I could not resist and got it.





Output current monitor included

position indicator of internal coil
real piece of art


DX today was 
T30D on 30m and 40m  and VK9DLX at 30M  and heard at 80M CW
I never received my complete call at 40m from T30D since the  QRM hooligan  started  jamming  again.  
" CQ DX "   over T30D  and of course hoping for reactions from frustrated ham's
to produce even more qrm..
The mother of idiots is always pregnant 


1 comment:

Jan / pa3abk said...

Hi Jaap,

=Your log entry is in English so will maintain it :-)

Sometimes I check your log.
You gave me"good" WSPR reception reports, was a bit curious how you did that :-)

Reading this blogitem you complaint about difficult tuning of the areal system.
Noticed that indeed the this type of tune tuner requires "fingerspitzengefuehl".

I use "the another method".
First step down to the impedance of your system and than tune it.

I took a "purple" toroid (diam about 3,5cm) and laid 18 litze windings on it.
These are fed by the QTX (50 Ohm).
Next I took flexible wire and made 4 windings as a start. One end to "earth" and in series the variometer towards the antenna.
Look at DL4YHF page: http://www.qsl.net/dl4yhf/mf/mf_antenna_variometer.png
You can do it with a switch, but constructionwise it's a lot of work.
The antenna will not change much over the time.

Now you vary the couple windings in such that the highest frequency is tuned properly when the QTX producing 100W (@ 5,5A 24VDC)
The variometer is reaching that at max, no current overshoot for the PA.
You should see a clear min to 5,5A to min curve when tuning.

This tuner is very easy to tune not so sharp as the one you are using. The bandwidth will increase when you have more "copper" in the air.

In the shack you now can "remote tune" the system by inserting a small piece of ferrite (old BC radio type) into the last coil of the PA.
Take the smallest ferrite you have, you only need a fraction to cover that 10kHz.

There is a "catch" on this.
You must observe the PA current carefully.
There is moment that the unit will deliver 100W but can't do more because of the ceiling of the power supply.
It will draw more current and finally it will flash out your PA FET.
So best is to stop "tune" when max current of 5,5A @ 24VDC is reached.

There will be a small mismatch in the coaxcable of course, but on this frequency it will not harm.
Remote tuning can also be done with a varco at the antenna end of the QTX

73's Jan/pa3abk

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