[ausmilsig] Fw: WSNo11 tx loading
- From: "pete williams" <jupete@xxxxxxxxxxxxxx>
- To: "ausmilsig" <ausmilsig@xxxxxxxxxxxxx>
- Date: Sat, 15 Apr 2006 16:00:57 +1000
Pete D . Williams
METUNG 3904
Australia
jupete@xxxxxxxxxxxxxx
----- Original Message -----
From: "pete williams" <jupete@xxxxxxxxxxxxxx>
To: <ausmilsig@xxxxxxxxxxxxxxx>
Sent: Friday, April 14, 2006 11:34 AM
Subject: Re: [Ausmilsig] WSNo11 tx loading
SENT TO RAY R. ON THE " HOPELESS "REFLECTOR !
Pete D . Williams
METUNG 3904
Australia
jupete@xxxxxxxxxxxxxx
----- Original Message -----
From: "Ray Robinson" <robinson@xxxxxxxxxxxxxxx>
To: <ausmilsig@xxxxxxxxxxxxxxx>
Cc: <robinson@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, April 11, 2006 11:13 AM
Subject: [Ausmilsig] WSNo11 tx loading
RAY n group---- as an addendum to the last--- what was/is the
antenna the #11 worked with? If any odd length over a tree, the end
feed impedance will be high esp of wire length is short and non
resonant at the operating freq.
If a short whip say 8' the radiation R at around 4 Mhz will be
around 0.2 ohm and the reactance around -1600 ohms . Getting rid
of/minimising the negative reactance means resonating the antenna
with a loading coil or other. Whip would load up real well at 28
MhZ!
I can't recall the output/loading configuration of a #11 but whatever
test setup you might use would have to take into consideration the
possible variations of antenna lengths .
Seems the light bulb is closest to design parameters assuming no
other problems in radio
73
Pete
Hi gang,
I was trying to load my WSNo11(Aust) transmitter last night,
but cannot get the aerial currents the manual suggests.
It says LP about 200ma, HP about 500ma, (and WftW suggests about 5
watts).
I can only get about 50ma into a dummy load which means about 1 watt.
My dummy load can be switched between 10 to 400 ohms resistive,
and 500 to 100 pf to none for a series capacitance,
tried all those, but the watt meter barely moves above 1 watt.
So I tried a real aerial and it is the same.
So I tried a 12vdc light bulb, and managed to get near the suggested
values.
The manual suggests a dummy load of 16 ohms and 100pf,
but the light bulb is far lower than this.
Perhaps I have a fault.
I changed the 807, checked all the voltages, HP and LP,
checked the bypass capacitors, dipped the tank with a GDO,
looked at the output frequencies on a spectrum analyser,
drove the 807 grid with a signal generator.
I tweaked the tx alignment.
Nothing helped.
The receiver is working very well,
and the RF amp, mixer, BFO are used for the transmitter,
so any fault there would degrade the receiever.
What am I missing?
Regards
Ray
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