-----Original Message-----
From: farmerik <farmerik@...>
To: ultralightdx <ultralightdx@...>
Sent: Tue, Jun 28, 2011 1:55 pm
Subject: [ultralightdx] Re: Tuned loop antenna

 
I would like to hear more about your spiral loop antenna, such as the
wire you used, and the spacing between turns.

I also experimented with diamond weave and rook wound coils of 10-12
inches on both AM and LW. Mostly I was hoping for TA LW, but it never
happened. Each coil acted differently, that is for sure. I have pretty
much given up trying for TA LW on a ULR without an amplified antenna.
Now I am more interested in AM BCB. - FARMERIK

P.S. - Was that a typo about the 310 being worse than the 380 regarding
soft mute? I thought it was the other way around, but I can easily be
confused.

--- In ultralightdx@..., Rick Robinson <w4dst@...>
wrote:

Hi Nick,

&gt; If you are handy with a soldering iron, the PL-310 is very simple
to
&gt; modify for external antennas. See the group files section for the

"Laurie" mod to the PL-310. The PL-380 mod is more involved but

is a
&gt; better radio due to its lack of extreme soft mute and AGC issues
that
&gt; the '310 has. I have modified my '310 and 2 '380s for use with
external

antennas. The Si4734 will tune any antenna in the 180uH to 400uH

range

with its built-in 500pf - 20pF varactor. No need to purchase

bulky

tuning capacitors, it's all in the radio. I used 1/8" stereo

jacks on

my PL-380s, and depending on the type of jack you use,you can keep

the

internal ferrite bar in place and usable when the external antenna

is

not being used.

I use a 24 inch spiral wound loop antenna with an inductance of

260uH

with my ULRs. BTW, a spiral wound loop has much sharper peaks and

nulls

than ferrite bar and "box wound" loops and is much quieter than

ferrite

bar antennas. However it is somewhat more difficult to construct

than a

"box wound" loop and is not as easily transported as a ferrite bar.

I've been using these modified ULRs for almost a year with no

problems

at all. The Si4734 is a robust chip and does an excellent job of

tuning

external MW antennas without use of external capacitors.

Good DXing,

Rick W4DST


On 6/27/2011 6:47 PM, g4irx_uk wrote:

Hi,

I've looked at some of the amazing ferrite rod antennas for

ultralights.

Has anybody tried a tuned loop antenna in place of the

ferrite rod, letting the si4734 do the tuning rather than a capacitor
on the loop? I have a large hexagonal loop and I'm considering mounting
the PL-380 on the loop frame itself, disconnecting the internal ferrite.

Nick.