K3S relay noise when using Rx ANT IN port

[raycollins]

My K3S is configured to use the RX ANT IN port for a separate Rx antenna.
However, on SSB transmissions I can hear an internal relay operating in
synchronism with peaks in transmit power.  I assume this is a relay in the
receiver input protection circuit?

Is operation of the relay in this manner normal? Apart from finding the
noise rather irritating I am concerned about the reliability of the relay
when it is called upon to operate so many times during a QSO.

The Tx and Rx antennas are about 10 metres apart and I am transmitting 100
Watts.

Thanks for your help,

Ray M1FJL



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[Jim AB3CV]

Ray

That is indeed the protective relay on the RX Ant port. You should find a
way to protect the RX Ant port from your TX signal.

There are many products in the market for his purpose. Not sure of the best
choice on your side of the Atlantic.

73

jim ab3cv

On Sat, Feb 1, 2020 at 5:23 PM raycollins <[hidden email]> wrote:

>
> My K3S is configured to use the RX ANT IN port for a separate Rx antenna.
> However, on SSB transmissions I can hear an internal relay operating in
> synchronism with peaks in transmit power.  I assume this is a relay in the
> receiver input protection circuit?
>
> Is operation of the relay in this manner normal? Apart from finding the
> noise rather irritating I am concerned about the reliability of the relay
> when it is called upon to operate so many times during a QSO.
>
> The Tx and Rx antennas are about 10 metres apart and I am transmitting 100
> Watts.
>
> Thanks for your help,
>
> Ray M1FJL
>
>
>
> --
> Sent from: http://elecraft.365791.n2.nabble.com/
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[Don Wilhelm]

Ray,

Your transmit signal is getting into your RX antenna with more energy
than is safe for the K3S.  10 meters is not much separation unless the
antennas are oriented so one is not in the null pattern of the other.

Using antennas that are of opposite polarization (such as a horizontal
dipole and a vertical) may be OK for a 10 meter separation, maybe not.

There are protective devices available that will disconnect the RX
antenna when the K3S is transmitting, and use of one of those may be the
quickest and easiest solution.

73,
Don W3FPR

On 2/1/2020 5:21 PM, raycollins wrote:

>
> My K3S is configured to use the RX ANT IN port for a separate Rx antenna.
> However, on SSB transmissions I can hear an internal relay operating in
> synchronism with peaks in transmit power.  I assume this is a relay in the
> receiver input protection circuit?
>
> Is operation of the relay in this manner normal? Apart from finding the
> noise rather irritating I am concerned about the reliability of the relay
> when it is called upon to operate so many times during a QSO.
>
> The Tx and Rx antennas are about 10 metres apart and I am transmitting 100
> Watts.
>

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[Bob McGraw - K4TAX]

I use a surplus coax relay, one with BNC connectors, and it is triggered
from the KEY OUT function on the transceiver along with the 12V
source.   Be sure and use a diode across the relay coil to prevent back
EMF.   The relay switches the RX ANT port to a 50 load, being a resistor
mounted in a BNC connector on the N.O contact port.  The common relay
port goes to the radio  RX ANT IN and the N.C. relay port goes to the
transceiver RX antenna. It only clicks when the PTT is active and
released.    As to CW, well that's another issue where the relay needs
to be held in during transmission or you'll hear it with every CW element.

I personally would be concerned about using solid state switching
devices in as much as a junction when saturated may be prone to produce
harmonic related energy.   However, there are circuits which use PIN
diodes or JFETS, designed correctly, would likely be clean.

73

Bob, K4TAX




On 2/1/2020 4:48 PM, Don Wilhelm wrote:

> Ray,
>
> Your transmit signal is getting into your RX antenna with more energy
> than is safe for the K3S.  10 meters is not much separation unless the
> antennas are oriented so one is not in the null pattern of the other.
>
> Using antennas that are of opposite polarization (such as a horizontal
> dipole and a vertical) may be OK for a 10 meter separation, maybe not.
>
> There are protective devices available that will disconnect the RX
> antenna when the K3S is transmitting, and use of one of those may be
> the quickest and easiest solution.
>
> 73,
> Don W3FPR
>
> On 2/1/2020 5:21 PM, raycollins wrote:
>>
>> My K3S is configured to use the RX ANT IN port for a separate Rx
>> antenna.
>> However, on SSB transmissions I can hear an internal relay operating in
>> synchronism with peaks in transmit power.  I assume this is a relay
>> in the
>> receiver input protection circuit?
>>
>> Is operation of the relay in this manner normal? Apart from finding the
>> noise rather irritating I am concerned about the reliability of the
>> relay
>> when it is called upon to operate so many times during a QSO.
>>
>> The Tx and Rx antennas are about 10 metres apart and I am
>> transmitting 100
>> Watts.
>>
> ______________________________________________________________
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[markmusick]

This is what I use.

https://www.dxengineering.com/search/product-line/dx-engineering-receiver-guard-electronic-rf-limiters?autoview=SKU&sortby=Default&sortorder=Default

DX Engineering Receiver Guard Electronic RF Limiter.

No relay involved.
       
K3LR designed these for his contest station.
If Tim is using these in his contest station, it should be more than adequate.

73,
Mark, WB9CIF

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Bob McGraw K4TAX
Sent: Sunday, February 2, 2020 01:16
To: [hidden email]
Subject: Re: [Elecraft] K3S relay noise when using Rx ANT IN port

I use a surplus coax relay, one with BNC connectors, and it is triggered from the KEY OUT function on the transceiver along with the 12V source.   Be sure and use a diode across the relay coil to prevent back EMF.   The relay switches the RX ANT port to a 50 load, being a resistor mounted in a BNC connector on the N.O contact port.  The common relay port goes to the radio  RX ANT IN and the N.C. relay port goes to the transceiver RX antenna. It only clicks when the PTT is active and released.    As to CW, well that's another issue where the relay needs to be held in during transmission or you'll hear it with every CW element.

I personally would be concerned about using solid state switching devices in as much as a junction when saturated may be prone to produce harmonic related energy.   However, there are circuits which use PIN diodes or JFETS, designed correctly, would likely be clean.

73

Bob, K4TAX




On 2/1/2020 4:48 PM, Don Wilhelm wrote:

> Ray,
>
> Your transmit signal is getting into your RX antenna with more energy
> than is safe for the K3S.  10 meters is not much separation unless the
> antennas are oriented so one is not in the null pattern of the other.
>
> Using antennas that are of opposite polarization (such as a horizontal
> dipole and a vertical) may be OK for a 10 meter separation, maybe not.
>
> There are protective devices available that will disconnect the RX
> antenna when the K3S is transmitting, and use of one of those may be
> the quickest and easiest solution.
>
> 73,
> Don W3FPR
>
> On 2/1/2020 5:21 PM, raycollins wrote:
>>
>> My K3S is configured to use the RX ANT IN port for a separate Rx
>> antenna.
>> However, on SSB transmissions I can hear an internal relay operating in
>> synchronism with peaks in transmit power.  I assume this is a relay
>> in the
>> receiver input protection circuit?
>>
>> Is operation of the relay in this manner normal? Apart from finding the
>> noise rather irritating I am concerned about the reliability of the
>> relay
>> when it is called upon to operate so many times during a QSO.
>>
>> The Tx and Rx antennas are about 10 metres apart and I am
>> transmitting 100
>> Watts.
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
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I would cease operating with the RX antenna connected immediately  
before you damage your transceiver. 10m antenna separation is very  
close. I has a similar situation at my P40A station so I shorted the  
RX coax with a relay during transmit.

GL,
John KK9A

M1FJL wrote:

My K3S is configured to use the RX ANT IN port for a separate Rx antenna.
However, on SSB transmissions I can hear an internal relay operating in
synchronism with peaks in transmit power.  I assume this is a relay in the
receiver input protection circuit?

Is operation of the relay in this manner normal? Apart from finding the
noise rather irritating I am concerned about the reliability of the relay
when it is called upon to operate so many times during a QSO.

The Tx and Rx antennas are about 10 metres apart and I am transmitting 100
Watts.

Thanks for your help,

Ray M1FJL

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[VE2EBK]

We use this unit during our portable operations

 

 <https://ea4tx.com/en/tienda/frontend-limiter/trx-fel/>
https://ea4tx.com/en/tienda/frontend-limiter/trx-fel/

 

73

 

Dany VE2EBK

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[Elecraft mailing list]

I'm somewhat surprised Elecraft don't just flip that relay into the
"protect" position whenever the radio Transmits.

Or at least have a menu option for that relay's behaviour, that defaults
to the "Safe" situation (RX made "Safe" during TX.)  But if you really
do need to, able to be set so the RX automatically protects itself when
it thinks it is needed, as at present.

73.

Dave G0WBX.


On 03/02/2020 05:29, [hidden email] wrote:
> [Elecraft] K3S relay noise when using Rx ANT IN port

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[Petr, OK1RP/M0SIS]

Dany,

it looks like the RX-FES (KD9SV) and AS-RXFEP (Array Solution) protection
units combined together... isn't it ? :)

Are you using it in SO2R or Multi-Multi config?

Ref:
AS-RXFEP Limiter: https://www.arraysolutions.com/surge-and-rf-protection/as-rxfep
RX-FESSS (KD9SV): https://www.dxengineering.com/parts/svp-sv-fesss
DXE-RG5000HD Limiter (K3LR): https://www.dxengineering.com/parts/dxe-rg5000hd
TRX-FEL (EA4TX): https://ea4tx.com/en/tienda/frontend-limiter/trx-fel/
RX-FEL FE Saver (FEP EA4TX): https://ea4tx.com/en/tienda/frontend-limiter/rx-fel/




-----
73 - Petr, OK1RP
"Apple & Elecraft freak"
B:http://ok1rp.blogspot.com
MeWe: https://bit.ly/2HGPoDx
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[Don Wilhelm]

But that would preclude allowing receive on the SubRX while transmitting
- in other words SOTR operation.

73,
Don W3FPR

On 2/3/2020 5:58 AM, Dave B via Elecraft wrote:
> I'm somewhat surprised Elecraft don't just flip that relay into the
> "protect" position whenever the radio Transmits.
>
> Or at least have a menu option for that relay's behaviour, that defaults
> to the "Safe" situation (RX made "Safe" during TX.)  But if you really
> do need to, able to be set so the RX automatically protects itself when
> it thinks it is needed, as at present.
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[Dave G3WGN M6O]

This FEP is available in the UK:
http://www.crosscountrywireless.net/receiver_protection_unit.htm 

OK1RR has a design for homebrew, based on KD9SV FES:
http://www.ok1rr.com/index.php/technical-topics/39-yet-another-front-end-saver

I have both of these and also an Array Solutions and a DXEngineering 5000
model.  
All of them do the job.  Yer pays yer money and yer makes yer choice...

73, David G3WGN M6O



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[Petr, OK1RP/M0SIS]

David,

the problem is that original KD9SV FES unit is not protecting your radio
against the another RF power sources (SO2R or MM site operation)... FES unit
is disconnecting ext. RX antenna and grounding the input RX port just when
the unit is activated by own radio PTT signal.

In that case the limiters like FEP seems to be much better and they will do
the job perfectly.

Martin, OK1RR has new design of the FEP RF diode limiter for homebrew, just
the article is in Czech language:
https://www.okdxf.eu/index.php/technika/272-ochrana-vstupnich-obvodu-prijimace

Do not worry to ask him for help. I am using his design as an upgrade of his
preview KD9SV saver project and it works perfectly as everything designed by
him.

An interesting thing on EA4TX TRX-FEL design is that it can protect also all
the main TRX ports on the radio (not only ext. RX antenna port) in SO2R and
MM operation.

Unfortunately I did not found any information about bypassing relay used in the unit. As it
is inserted in the TX path then this relay will be key part of T/R switching of the transceiver.
So question is how fast the relay is and how it will affect the full break-in (QSK) operation of
radios like K3/K3S...

Ref:
AS-RXFEP Limiter (Array): https://www.arraysolutions.com/surge-and-rf-protection/as-rxfep
RX-FESSS (KD9SV): https://www.dxengineering.com/parts/svp-sv-fesss
DXE-RG5000HD Limiter (K3LR): https://www.dxengineering.com/parts/dxe-rg5000hd
TRX-FEL (EA4TX): https://ea4tx.com/en/tienda/frontend-limiter/trx-fel/
RX-FEL FE Saver (FEP EA4TX): https://ea4tx.com/en/tienda/frontend-limiter/rx-fel/
RFEP (Cross Country) UK: http://www.crosscountrywireless.net/receiver_protection_unit.htm 
FES KD9SV (OK1RR): http://www.ok1rr.com/index.php/technical-topics/39-yet-another-front-end-saver
FEP Diode Limiter (OK1RR): https://www.okdxf.eu/index.php/technika/272-ochrana-vstupnich-obvodu-prijimace



-----
73 - Petr, OK1RP
"Apple & Elecraft freak"
B:http://ok1rp.blogspot.com
MeWe: https://bit.ly/2HGPoDx
MeWe: https://bit.ly/2FmwvDt
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[Petr, OK1RP/M0SIS]

Just FYI,

as Pablo, EA4TX confirmed the relay used for T/R switching to bypassing FEL
while radio is transmitting has operating time in between 5-7ms and
releasing time even 7-10ms if parallel diode is used.

So it looks like it is not usable on CW ...if your K3 will start transmitting first
element previously then FEL limiter is bypassed the RF power from K3 can
damage the limiter.
If your K3 will be back in RX mode again faster then FEL released to
protection path then your K3 is not protected during that period...





-----
73 - Petr, OK1RP
"Apple & Elecraft freak"
B:http://ok1rp.blogspot.com
MeWe: https://bit.ly/2HGPoDx
MeWe: https://bit.ly/2FmwvDt
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