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LF: Re: Re: Re: Re: RX in OZ

To: [email protected]
Subject: LF: Re: Re: Re: Re: RX in OZ
From: "captbrian" <[email protected]>
Date: Fri, 13 Aug 2004 09:01:24 +0100
References: <[email protected]> <[email protected]> <[email protected]> <[email protected]>
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,,,and what is the impedance at the ends of the loop _before_ Z translator ? ?
----- Original Message -----
From: F6CWN
Sent: Friday, August 13, 2004 1:26 AM
Subject: LF: Re: Re: Re: RX in OZ

12./08/2004   2223z
Hello Ingolf,
 Thanks for the infos, indeed,i should appreciate some additionals
comments if you have some time...
My system use very old 75 Ohms Andrew ( or something like that)
 coax cable out of order for VHF activity.( normaly i use it for 80 or
 160m dipole!)
Only the braid is used, with a space of 3.5 time the diameter between
every turn. The spacers are PVC type, but without lead ( you test it in
 the  µwave oven, it must be cold!). The number of turns is always even,
 for a central pick up to the ground. The tune capacity must to be a
very good one to keep high Q ( very important). I use PTFE capacitor or
mica type. The variable capacitor is a little one ( around 150 pF air model with
very good ground contacts). I use a little DC motor and a gear box to tune
this system from the station ( essential if you want to have the peace with
your neighbouring, otherwise take the audio to the maximum, open the window
and tune for max noise... at 2 o'clock in the morning it's super!  :0)  )
A little relay switch a additional capacitor to increase the band.
On the middle of the loop, i put a little second loop ( around 30 cm of diameter),
one turn, connect to a simple coax cable, this loop is used to  tune the RX
equipment to the desired frequency with the transmit generator ( ultra QRP
of course!), then the tune for max is very easy from the shack ( and more
At the two end of the loop i put a preamplifier ( not exactly preamplifier, rather
Z translator ) to convert the high Z symmetrical from the loop to 50 Ohms asymmetric.
I test many configurations (valves, bipolar and MOS) but at this moment no significant
results...( say you more in the 10 futures years...)
All this thingamajig ( loop, tune system, preamp ,rotator) is at about 1.5 meter AGL.
I must continue the investigations, but XYL ( F6IFR ) find me some other entertainings
during the freetime! (hi!)
To be continued...
Vy 73
Jeff / F6CWN
----- Original Message -----
From: OZ7QC
Sent: Thursday, August 12, 2004 9:28 PM
Subject: LF: Re: Re: RX in OZ

Hi Jeff,
Thanks for your reply
Yes I think I can receive him to but at the moment there is to much crack from thunder storm her in the array.
I have made the loop out of VE7LS idea, but with 40 turns 0,5mm in a special way to avoid internal capacity for the tuning coil, and 2 turns for the RX coil.
I don't have data or picture of my antenna yet but if you are interested I can produce some specification for you.
Vy 73
Ingolf OZ7QC
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