Message-ID: <005d01c09f15$48ddd100$a77a74d5@w8k3f0>
From: "Dick Rollema" <d.w.rollema@freeler.nl>
To: rsgb_lf_group@blacksheep.org
References: <000701c09dcf$6830e5c0$14b401d5@default> <14WhOa-2CnHRwC@fwd03.sul.t-online.com>
Subject: LF: Re: G3NYK/PA0SE-bridges
Date: Sun, 25 Feb 2001 11:22:34 +0100
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Uwe, DJ8WX, wrote:

> Dick, where did you get that Wayne-Kerr-B.601-bridge from ?
> could one  purchase it somewhere?

I have two Wayne Kerr admittance bridges:

Type B601: 15 kHz - 15 MHz

Type B801: 1 MHz - 100 MHz

But my home made noise bridge performs almost as well. I took great care to
make it frequency independent and succeeded in doing so up to 30 MHz.

I bought the Wayne Kerr bridges for little money in a war surplus shop and
at a rally of the Dutch Society for the History of Radio.
You can usually pick up older type of test equipment at rallies at low
prices because most  present day amateurs are of the "Steckdose" type
and are not at all interested  in measuring gear.

I tested my bridges by connecting them to a 3 m long piece of RG213 type 50
ohm coax that was terminated by a 50 ohm resistor (actually two 100 ohm
resistors in parallel). That produces a standing wave ratio of 2 in the
cable. The impedance at the input of the cable was measured at a range of
frequencies up to 30 MHz. When the results are plotted on a RX-diagram they
must lie on a circle; the one for SWR = 2. For the Wayne Kerr bridges this
was indeed the case. But the deviation from the circle was also very small
for my home made bridge. Only 30 MHz near the measured impedances tended to
lie inside the circle for all three bridges. This was caused by the loss in
the coax that made the SWR < 2 at the input of the cable.


> BTW.Dick, I just answered ur cq on 136 kHz. sri u did not hear my signal.
u
> where 559 in j043sv (ant: inverted V with 340m es 400m lws).

A pity I did not hear you. Perhaps some other time?

73, Dick, PA0SE