RANT front end protection

[Gil Stacy]

I have seen advertised front end protectors recommended for use when
utiilzing a separate antenna for receive.  Does the K2's RANT option on the
160 board offer sufficient protection for use with a separate preamp and RX
antenna or is it prudent to use a front end protector such as designed by
KD9SV?
Thanks,
Gil NN4CW
K2 #3104


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[Augie "Gus" Hansen]

On 2/8/06 3:14 PM, "Gil Stacy" <[hidden email]> wrote:

> I have seen advertised front end protectors recommended for use when
> utiilzing a separate antenna for receive.  Does the K2's RANT option on the
> 160 board offer sufficient protection for use with a separate preamp and RX
> antenna or is it prudent to use a front end protector such as designed by
> KD9SV?
> Thanks,

The K2 is the only current production HF transceiver that I know of that has
the "front-end saver" built in. The RECEIVE ANTENNA RELAY, K2 on the K160RX
board, disconnects the RX antenna during transmissions. If you're running a
standalone station, no problem.

In an SO2R or other multi-station contest environment (or if you have a "big
gun" station next door), you will probably need to take additional
protective measures. Your best bet is to get a copy of "Managing
Interstation Interference" by W2VJN (George of INRAD fame). He does a great
job of describing the problems and solutions.

Gus Hansen, KB0YH

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[Darrell Bellerive]

On February 8, 2006 04:15 pm, Augie (Gus) Hansen wrote:
> The RECEIVE ANTENNA RELAY, K2 on the
> K160RX board, disconnects the RX antenna during transmissions.

Gee, I hope not. I thought that the K2 was completely solid state T/R
switching. No clacking relays.

Darrell  VA7TO  K2 # 5093
--
Darrell Bellerive
Amateur Radio Stations VA7TO and VE7CLA
Grand Forks, British Columbia, Canada
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[K3yt]

Latching relays are used for the 160M band pass filter and the RX antenna  
switch
 
from the K160 RX manual
 
K3YT
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[K3yt]

sri that should say low pass
 
K3YT
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[Jack Brindle]

Darrell is correct. The relay on the K160RX board switches the RX  
path either to the main antenna or the external RxAnt jack. it is, of  
course, latching. The RxAnt is NOT grounded when it is not selected,  
not is the main antenna jack (of course).

Be aware that there is some leak-through that may occur through this  
relay. I had four QSOs (one with W5WMU in La.) during the first 15  
minutes of the 2004 Phone Sweepstakes before discovering I had RxAnt  
turned on! Yeah, the bands did seem dead...

With the Rx path being pretty much the same whether the main antenna  
or the RxAnt is selected, you have about the same opportunity for  
receiver overload either way. I wouldn't expect this to be a big  
problem. As others have mentioned, having a strong signal nearby  
while your are trying to receive is a different matter, and calls for  
bandpass filters and the like to keep that signal from desensing your  
K2.

On Feb 8, 2006, at 4:29 PM, Darrell Bellerive wrote:

> On February 8, 2006 04:15 pm, Augie (Gus) Hansen wrote:
>> The RECEIVE ANTENNA RELAY, K2 on the
>> K160RX board, disconnects the RX antenna during transmissions.
>
> Gee, I hope not. I thought that the K2 was completely solid state T/R
> switching. No clacking relays.


-Jack Brindle, W6FB
=======================================================================


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[Tom Hammond-3]

Additionally, newer production K2s also include back-to-back diodes
(1N4148) across the RX antenna input, actually across pins 4 & 6 of
U12 on the RF board. These diodes do a great job of protecting the K2
from very strong nearby transmitters.

I'd doubt that you might need too much more.

When I was field testing this mod prior to its being accepted, I had
the K2 connected to my 80/40/30 triple-wire inv-V which is situated
3' below my tribander, and I transmitted with a KW into the tribander
and received on the K2 with no damage to the K2's front end, or to
any other of the RF stages.

73,

Tom   N0SS

At 06:15 PM 2/8/2006, Augie (Gus) Hansen wrote:

>On 2/8/06 3:14 PM, "Gil Stacy" <[hidden email]> wrote:
>
> > I have seen advertised front end protectors recommended for use when
> > utiilzing a separate antenna for receive.  Does the K2's RANT option on the
> > 160 board offer sufficient protection for use with a separate preamp and RX
> > antenna or is it prudent to use a front end protector such as designed by
> > KD9SV?
> > Thanks,
>
>The K2 is the only current production HF transceiver that I know of that has
>the "front-end saver" built in. The RECEIVE ANTENNA RELAY, K2 on the K160RX
>board, disconnects the RX antenna during transmissions. If you're running a
>standalone station, no problem.
>
>In an SO2R or other multi-station contest environment (or if you have a "big
>gun" station next door), you will probably need to take additional
>protective measures. Your best bet is to get a copy of "Managing
>Interstation Interference" by W2VJN (George of INRAD fame). He does a great
>job of describing the problems and solutions.
>
>Gus Hansen, KB0YH
>
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[wayne burdick]

Just to be clear on one point: the K2 *does not* switch any relays
between transmit and receive. T/R switching is always done using PIN
diodes.

When you enable the receive antenna (RANT ON), you're simply routing
the receive antenna -- rather than the main antenna -- to the receiver.

73,
Wayne
N6KR


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[Don Wilhelm-3]

Gil,

I doubt that a 'front-end protector' would be required on the K2 RANT
input - the input path is through D3 and D4 in the T/R switch, and both are
back biased with the 8T signal during transmit - so as long as the peak
signal on the receive antenna is less than the bias voltage on the diodes (8
volts), the signal should not get through - OK, consider 2,67 volts for a
safety factor of 3).  If you feel that this is not good enough, you may want
to install a pair of back to back diodes directly across the receive antenna
jack.

As for the protection of a separate receive preamp - I can give no response
since I know nothing about your particular preamp and connections - again, a
pair of back to back diodes (1N4148 or similar) across the preamp input
should provide adequate protection if required - a couple of 1N4148 diodes
is likely much less expensive than a commercial 'front-end protector', and I
would guess that such a device is nothing more than a pair of diodes (of
course, I am speaking from ignorance since I have not investigated any such
devices).

73,
Don W3FPR

> -----Original Message-----
>
> I have seen advertised front end protectors recommended for use when
> utiilzing a separate antenna for receive.  Does the K2's RANT
> option on the
> 160 board offer sufficient protection for use with a separate
> preamp and RX
> antenna or is it prudent to use a front end protector such as designed by
> KD9SV?
> Thanks,
> Gil NN4CW
> K2 #3104
>
>

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