Hi Luis,
Am 18.10.2015 00:49, schrieb VIGILANT Luis Fernández:
Hi
Stefan
Yes. I have already doubled the voltage rate of the output
filter. It was the second thing that
failed when transmitting with the loop.
Oh, very strange. That cannot happen when an antenna system is matched
properly, whatever antenna is used.
Output ferrite transformer is also cooled with fan and
small aluminium heatshink. Temptation to keep transmitting is
too strong ! ;-)
The output transformer inside the PA or do you have an external one?
Fortunately, even severy mismatched, the vertical is stable as a
rock.
Yes, because it is not resonanted yet :-)
The loop need continous
watching because capacitors heat and mismatch drifts from on Tx
to the next one. A real hell !
Hm, with my small loop that i used for TXing, there were heat problems
too. But the drifting working points limits itselfe, due to the
temperature coeffcient of the capacitor. It just runs out of resonance
which reduces the voltage, current and temperature to an acceptable
value.
It is just what you predicted :-)
Of course I need help from you all to match the PA. I have
finished the coil this afternoon
120 turns of 0.9mm enameled copper over 25cm composite pipe.
25 cm is a good choice.
The plan is not to use taps
but use a ferrite transformer with taps to match.
That is a good decision too. But you will need a variometer part inside
the coil, maybe 15 turns on a 8cm diameter tube.
Later you won't need taps on the transformer. Once you have found the
right ratio of turns, it will not change dramatically. However the
resonance may be quite sharp because you need much L at such a short
antenna.
I have also an small variometer which can be
added
I wonder if the 490pF vacuum variable capacitor can be of use at
any point in the matching
No, not really. All you need is the variometer and the transformer.
You already found the resonance of the loop so i think you will find it
on the vertical too.
Do not use SWR meters, they are sub-optimal on LF/MF i find.
BTW i recommend to use separate primary and secondary windings on the
transformer to decouple the system. This also helps to avoid QRM/TVI to
others. A correctly wound transformer is cold, even at 100W passing
through it. Otherwise it saturates! Then you need more turns on the
primary side! This is a first thing that you could check by winding a
1:1 transformer and see if it stays cool when running full power into a
dummy load for a few minutes.
I guess your loss resistance could be in the range of 50 Ohm, so you
may need a 1:1.4 winding ratio.
You will see...
73, Stefan
Hope to get it installed soon
73 de Luis
EA5DOM
Hi Luis,
Be careful with running a mismatched PA. It may not blow up the FETs
but maybe a C in the output filter. And the filter will not work very
well too.
I guess you know how to match the antenna to the PA. Or do you need
some advice and suggestions?
159V is nothing, it could be 20 dB more, easily. So i'm looking forward
to your loaded antenna :-)
73, Stefan
Am 17.10.2015 16:33, schrieb VIGILANT Luis Fernández:
Thank
you Stefan :-)
This is being posible with the help of many friends found here
in the reflector, like you
This morning I have added the loop to the ground side of the
vertical (dipole). No difference
in the loading. Still mismatched. The PA rms out is 159V and
input power 9A@12V
That should be 62V rms over a 50Ohm load. Anyway much better
and less stressing
working conditions that a high Q loop and can run WSPRS every
8 minutes without problems
For the QRSS-3 QSO can be tomorrow sunday evening. Today I'll
be out and just running WSPR
What a coincidence ! It will also be my first QSO with DL on
this band. In fact, will be my first QSO
in this band ! :)
No pictures about the arrangement because there is no
arrangement. Just the vertical antenna
The radial go down inside the building trought a ventilation
pipe. Let's see tonight if the loop around
the base of the vertical antenna makes some difference and can
reach LA !
73 de Luis
EA5DOM
Hi Luis,
My congrats!!!
This is a very good result for an unloaded 10m vertical antenna!
The coil will make a big difference, a few 10 dB i expect, although
this is hard to imagine since your reports are very good already.
Do you like to try a QRSS-3 (or DFCW) QSO? :-) Would be my first on
that band to EA.
73, Stefan
PS: Show us some photos of the new arrangement.
19 spots:
| Timestamp |
Call |
MHz |
SNR |
Drift |
Grid |
Pwr |
Reporter |
RGrid |
km |
az |
| 2015-10-16 23:40 |
EA5DOM |
0.475791 |
-30 |
0 |
IM98wn |
0.05 |
DG3LV |
JO53gv |
1887 |
22 |
| 2015-10-17 01:56 |
EA5DOM |
0.475789 |
-29 |
0 |
IM98wn |
0.05 |
PI4THT |
JO32kf |
1613 |
17 |
| 2015-10-16 20:24 |
EA5DOM |
0.475790 |
-25 |
0 |
IM98wn |
0.05 |
DH5RAE |
JN68qv |
1576 |
39 |
| 2015-10-17 00:24 |
EA5DOM |
0.475788 |
-29 |
0 |
IM98wn |
0.05 |
DJ0ABR |
JN68nt |
1556 |
39 |
| 2015-10-16 23:40 |
EA5DOM |
0.475789 |
-29 |
0 |
IM98wn |
0.05 |
DF6MK |
JN68ik |
1505 |
39 |
| 2015-10-16 20:40 |
EA5DOM |
0.475789 |
-28 |
0 |
IM98wn |
0.05 |
PA0RDT |
JO11tm |
1470 |
10 |
| 2015-10-17 03:32 |
EA5DOM |
0.475790 |
-24 |
0 |
IM98wn |
0.05 |
G8HUH |
IO81mg |
1430 |
352 |
| 2015-10-17 01:56 |
EA5DOM |
0.475789 |
-33 |
0 |
IM98wn |
0.05 |
G3XKR |
IO70ux |
1419 |
348 |
| 2015-10-17 00:08 |
EA5DOM |
0.475791 |
-20 |
0 |
IM98wn |
0.05 |
DK7FC/P |
JN49ik |
1398 |
27 |
| 2015-10-17 00:32 |
EA5DOM |
0.475791 |
-30 |
0 |
IM98wn |
0.05 |
DK7FC |
JN49ik |
1398 |
27 |
| 2015-10-16 23:24 |
EA5DOM |
0.475789 |
-28 |
0 |
IM98wn |
0.05 |
DL6RCN |
JN58kg |
1395 |
36 |
| 2015-10-17 02:00 |
EA5DOM |
0.475789 |
-25 |
0 |
IM98wn |
0.05 |
F6CNI |
JN19qb |
1200 |
12 |
| 2015-10-17 04:48 |
EA5DOM |
0.475790 |
-29 |
0 |
IM98wn |
0.05 |
F4HBT |
JN08qx |
1164 |
5 |
| 2015-10-16 22:32 |
EA5DOM |
0.475789 |
-30 |
0 |
IM98wn |
0.05 |
F6GEX |
IN97na |
942 |
357 |
| 2015-10-17 02:56 |
EA5DOM |
0.475791 |
-29 |
0 |
IM98wn |
0.05 |
F1AFJ |
JN06ht |
919 |
4 |
| 2015-10-17 02:00 |
EA5DOM |
0.475789 |
-29 |
0 |
IM98wn |
0.05 |
F5OZF |
IN94su |
700 |
358 |
| 2015-10-17 03:24 |
EA5DOM |
0.475792 |
-18 |
0 |
IM98wn |
0.05 |
EA2HB |
IN93ah |
550 |
344 |
| 2015-10-17 00:00 |
EA5DOM |
0.475789 |
-25 |
0 |
IM98wn |
0.05 |
EB3FRN |
JN01mc |
300 |
19 |
| 2015-10-17 05:48 |
EA5DOM |
0.475789 |
+4 |
0 |
IM98wn |
0.05 |
EA5DOM-1 |
IM98xn |
7 |
90 |
Am 17.10.2015 00:28, schrieb VIGILANT Luis Fernández:
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