[Elecraft] Antenna overload

Sat Jan 4 07:06:01 2003

In the 80's , when a group and I went to the Caribbean, one guy ( Jim,
K8MR ) designed a pad in a metal box that went into the RECEIVE line ONLY
and it would switch in 20 or 40 db of attenuation ! I used the 40 db setting
with the old ( new then ) ts-830 I had and with a KW running right next to
me could still run a pile up to Europe , no problem at all :-) We were VP2E
.............. with different last letters. I happened to be VP2ES :-) but
they have re-issued this call many time since then.

Walt

----- Original Message -----
From: "John, KI6WX" <[email protected]>
To: "Elecraft Mailing List" <[email protected]>
Sent: Friday, January 03, 2003 2:55 PM
Subject: [Elecraft] Re: mod to allow K2 to handle huge in-band
signals--please try

> Placing the diodes across the K2 antenna jack would decrease the dynamic
> range of the K2.  Strong broadcast signals and other out of band signals
> would intermodulate each other producing lots of non-wanted signals right
in
> the amateur bands.
>
> Placing the diodes after the Xtal filter guarantees that only inband
signals
> would be strong enough to cause diode conduction.  The filter following
the
> IF amp removes some of the distortion caused by the diodes.
>
> -John
>  KI6WX
>
>
> I had exactly the same reaction as Gary ... why would anyone transmit on
the
> same frequency in such close proximity to each other?  Now with Eric's
> explanation, I understand the HFpackers' application and it makes sense.
>
> However, I don't understand why the protection is applied to the IF amp
> rather than the antenna jack.  Isn't it possible to fry stuff between the
> antenna and the IF?
>
> Back in May during our QRO (KW amps) multi-multi operation from 6Y, we
were
> very concerned about damaging our K2's by harmonics from other bands
getting
> into our RX Antenna jack (with RX antenna connected and in close proximity
> to all the other antennas).  Eric and Wayne suggested a back-to-back diode
> solution and even a series resistor to clamp the voltage and limit the
> current at the jack itself.  This has always been a concern with
commercial
> rigs and it is common to blow up something in their front end.  Perhaps
the
> K2 front end is more robust?
>
> 73,
> Ed - W0YK
>
>
>
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