[R-390] Positive ground (slightly off topic)

Tue, 3 Sep 2002 10:43:13 -0400

You can use high quality high voltage transmitting-type capacitors, high
enough in value that they present a negligible impedance in the lowest RF
frequency you're going to use.  A good  5000-10000 pf cap would work fine
(or a few lower capacitance ones in parallel - this would reduce the
inductive reactance of the capacitors even further).

73, Meir WF2U

Landrum, SC

 -----Original Message-----
From: 	[email protected] [mailto:[email protected]]  On
Behalf Of AI2Q Alex
Sent:	Tuesday, September 03, 2002 9:50 AM
To:	R-390 (E-mail)
Cc:	'Bill Smith'
Subject:	RE: [R-390] Positive ground (slightly off topic)

Thanks for your idea Bill. I have been toying with something similar to what
you suggest, insulating the base of the antenna (normally grounded), and
using coupling caps. However, I want to use this as a multi-band set-up, and
using caps may preclude that due to the different values of capacitive
reactance on each band.

My other thought is to use an auxiliary battery, with a DPDT switch. In
"normal" use, the second battery could be across the car's main battery, and
get charged from the vintage car's generator. Then, when I throw the DPDT
switch, I could ground the negative terminal of the secondary battery, and
feed the positive voltage to the rig. I may wind up doing that.

Vy 73, AI2Q, Alex  .-.-.

-----Original Message-----
From: Bill Smith [mailto:[email protected]]
Sent: Monday, September 02, 2002 5:19 PM
To: [email protected]; R-390 (E-mail)
Subject: Re: [R-390] Positive ground (slightly off topic)

How about coupling with large value capacitors (0.005, 0.01 mfd)?   Transmit
Mica caps should do the trick.  You should also "ground" your rig with
similar caps.  I am assuming your rig is insulated from the automobile
chassis due to reverse polarity (positive ground).

73 de Bill, AB6MT
[email protected]

----- Original Message -----
From: "AI2Q Alex" <[email protected]>
To: "R-390 (E-mail)" <[email protected]>
Sent: Monday, September 02, 2002 1:50 PM
Subject: [R-390] Positive ground (slightly off topic)

> Hello all:
>
> Given the pool of technical knowledge on this list, I wonder if anyone can
> suggest a way to feed a typical HF mobile whip antenna (center loaded,
with
> low-Z feedpoint) in an installation where the car's electrical system uses
a
> positive ground.
>
> I tried feeding a Hustler whip through a homemade toroidal coupling
> transformer in order to achieve DC isolation, but my transformer seems
> inadequate to achieve adequate coupling. I'm not interested in reversing
the
> vintage car's system polarity. The transceiver is an Atlas-210X.
>
> Any thoughts?
>
> Vy 73, AI2Q, Alex   .-.-.
>
>
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