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Testing BL1 mini module

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Chuck Gehring

Testing BL1 mini module

I finished assembling a BL1 BALUN Module and decided to test it with my 259
Antenna Analyzer.
The testing procedure calls for you to connect a pair of 100 ohm resistors
in series between the two 200 ohm terminals, then test the SWR with a jumper
connected to the input shield and to three different locations on the
resistors. The instructions state that the SWR should be low when the
jumper is connected between the input shield and the junction between the
two resistors. Then it should show poor SWR when the jumper is connected
between the input shield and either one of the BALUN output terminals. My
tests showed no difference between any of the three connections. I have
double and triple checked my soldering connections on the BL1. It is not a
complicated module to assemble.
Has anyone else tested the BL1 with a 259?
Is the BALUN safe to use or should I just stay away from testing equipment
without adult supervision?

73, KI4DGH
Chuck Gehring

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Charles Greene

Re: Testing BL1 mini module

Chuck,

I don't have one, but I have the manual and have studied it and the
balun. I would test it by placing the 200 ohms across the antenna
connections, and connect the 259 to the 50 ohm connection. It is a voltage
balun, but should have a decent SWR from 3.5 to 29 MHZ when so
connected. If it still doesn't read 1.2:1 or less, check your connections
of all the wires.

Chas, W1CG

At 01:38 PM 11/26/2004, Chuck Gehring wrote:

>I finished assembling a BL1 BALUN Module and decided to test it with my 259
>Antenna Analyzer.
>The testing procedure calls for you to connect a pair of 100 ohm resistors
>in series between the two 200 ohm terminals, then test the SWR with a jumper
>connected to the input shield and to three different locations on the
>resistors. The instructions state that the SWR should be low when the
>jumper is connected between the input shield and the junction between the
>two resistors. Then it should show poor SWR when the jumper is connected
>between the input shield and either one of the BALUN output terminals. My
>tests showed no difference between any of the three connections. I have
>double and triple checked my soldering connections on the BL1. It is not a
>complicated module to assemble.
>Has anyone else tested the BL1 with a 259?
>Is the BALUN safe to use or should I just stay away from testing equipment
>without adult supervision?
>
>73, KI4DGH
>Chuck Gehring
>
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
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>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

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Robert Friess

Re: Testing BL1 mini module

In reply to this post by Chuck Gehring

Hi Chuck,

I designed the BL1 for Elecraft and I am curious as to where you got the
testing procedure that you describe. I don't find it on the posted manual
and it is certainly not what I wrote.

That said, the behavior that you observe is exactly what I would expect the
BL1 to do. Shorting one side to the ground side of the coax will have
little effect on SWR except at the lowest frequencies where you are removing
part of the transformer inductance. In normal operation, i.e. no short, the
two halves of the transformer are connected in series which improves the low
frequency response.

Testing the BL1 with a 200 ohm resistor across the output terminals and
looking at the SWR at the coax connector is entirely adequate. No shorts,
opens etc. are needed.

73,
Bob, N6CM

----- Original Message -----
From: "Chuck Gehring" <[hidden email]>
To: <[hidden email]>
Sent: Friday, November 26, 2004 10:38 AM
Subject: [Elecraft] Testing BL1 mini module

>I finished assembling a BL1 BALUN Module and decided to test it with my 259
> Antenna Analyzer.
> The testing procedure calls for you to connect a pair of 100 ohm resistors
> in series between the two 200 ohm terminals, then test the SWR with a
> jumper
> connected to the input shield and to three different locations on the
> resistors. The instructions state that the SWR should be low when the
> jumper is connected between the input shield and the junction between the
> two resistors. Then it should show poor SWR when the jumper is connected
> between the input shield and either one of the BALUN output terminals.
> My
> tests showed no difference between any of the three connections. I have
> double and triple checked my soldering connections on the BL1. It is not
> a
> complicated module to assemble.
> Has anyone else tested the BL1 with a 259?
> Is the BALUN safe to use or should I just stay away from testing equipment
> without adult supervision?
>
> 73, KI4DGH
> Chuck Gehring
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>