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2 radios, 1 antenna... finally a prototype!

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JEAN-FRANCOIS MENARD-3

2 radios, 1 antenna... finally a prototype!

Hi,

I finally did a first prototype of an interface to link two K2/KPA100
on one multi-band HF antenna using Don W3FPR schematic. For my first
"from scratch" project, it is not too bad. I first began to do a PCB.
I used two fast SPDT 16A relays from Omron and SO-239 connectors are
Amphenol.

I will try it tonight.... But on the bench test, everything was
working fine... Maybe I will need to put a few caps to filter some
RF, I'm not sure.... I will tell you later tonight. This is my first
prototype version... My « main goal » is to have a interface like
this one, but also one mic and one paddle for 2 radios.

Unfortunatly, I forgot to take picture of my PCB. But I will put
Don's schematic on my website this week.

Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html

73

P.S. Many thanks to Don W3FPR for his help. ;-)

=============================================
/¯\/¯\/¯\/¯\/¯\/¯\ JEAN-FRANCOIS MENARD
V A 2 V Y Z
\_/\_/\_/\_/\_/\_/

FISTS #11896
Elecraft K2 #4130
Elecraft KX1 #999

http://homepage.mac.com/jfmenard
=============================================

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JEAN-FRANCOIS MENARD-3

Re: 2 radios, 1 antenna... finally a prototype!

Just to make sure I'm clear on my message... this interface is made
for listening on two radios at the same time from one antenna. But
when one radio transmit, the other in mute by putting it's antenna on
ground and vice-versa.

Le 05-11-19 à 18:02, JEAN-FRANCOIS MENARD a écrit :

> Hi,
>
> I finally did a first prototype of an interface to link two K2/
> KPA100 on one multi-band HF antenna using Don W3FPR schematic. For
> my first "from scratch" project, it is not too bad. I first began
> to do a PCB. I used two fast SPDT 16A relays from Omron and SO-239
> connectors are Amphenol.
>
> I will try it tonight.... But on the bench test, everything was
> working fine... Maybe I will need to put a few caps to filter some
> RF, I'm not sure.... I will tell you later tonight. This is my
> first prototype version... My « main goal » is to have a interface
> like this one, but also one mic and one paddle for 2 radios.
>
> Unfortunatly, I forgot to take picture of my PCB. But I will put
> Don's schematic on my website this week.
>
> Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html
>
> 73
>
> P.S. Many thanks to Don W3FPR for his help. ;-)
>
> =============================================
> /¯\/¯\/¯\/¯\/¯\/¯\ JEAN-FRANCOIS MENARD
> V A 2 V Y Z
> \_/\_/\_/\_/\_/\_/
>
> FISTS #11896
> Elecraft K2 #4130
> Elecraft KX1 #999
>
> http://homepage.mac.com/jfmenard
> =============================================
>
>
>
> _______________________________________________
> 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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>
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> Elecraft web page: http://www.elecraft.com

Dan Barker

RE: 2 radios, 1 antenna... finally a prototype!

I'm not a so2r kinda guy, but I've read that stereo will help. Seems
reasonable - If the left ear hears CQ, answer with the left radio.

Anyhow, you may want to do some AF-OUT magic in the same box. You'd probably
want a switch for selecting what it does. Maybe K2#1 in left, K2#2 in right
or Last-To-Transmit in both and the other in the corresponding single ear,
or something else alltogether.

Dan / WG4S / K2 #2456

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of JEAN-FRANCOIS
MENARD
Sent: Saturday, November 19, 2005 6:36 PM
Cc: Elecraft - Maling List Elecraft - Mailing List
Subject: Re: [Elecraft] 2 radios, 1 antenna... finally a prototype!

Just to make sure I'm clear on my message... this interface is made
for listening on two radios at the same time from one antenna. But
when one radio transmit, the other in mute by putting it's antenna on
ground and vice-versa.

Le 05-11-19 à 18:02, JEAN-FRANCOIS MENARD a écrit :

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Jack Brindle

Re: 2 radios, 1 antenna... finally a prototype!

In reply to this post by JEAN-FRANCOIS MENARD-3

There is one important step in the construction of the circuit that
should make it work well.

Now it is important to take this step...

What is the step?

Contact W6FB in the Phone Sweepstakes - I need the VA2 QSO!

:-) :-) :-)

Good luck making it run. Don and I had fun collaborating on that one...

On Nov 19, 2005, at 3:02 PM, JEAN-FRANCOIS MENARD wrote:

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

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Don Wilhelm-3

RE: 2 radios, 1 antenna... finally a prototype!

Yes folks, Jack and I collaborated on the design of this one. I started
with a few logic gates, and Jack kept saying 'do it with no active devices -
anyway, you can see the result in Jean-Francois website and judge for
yourself.

Since Jean-Francois gave me credit in his posts, I thought I should pass
along extra credit where it is due, and Jack deserves it.

BTW, if I ever get both my K2s to the operating position instead of one in
th eworkshop and the other for operating, I will be using this arrangement
myself - not fully SO2R, but a reasonable compromise suitable for my
operating.

73,
Don W3FPR

> -----Original Message-----

>
> There is one important step in the construction of the circuit that
> should make it work well.
>
> Now it is important to take this step...
>
> What is the step?
>
> Contact W6FB in the Phone Sweepstakes - I need the VA2 QSO!
>
> :-) :-) :-)
>
> Good luck making it run. Don and I had fun collaborating on that one...
>
> On Nov 19, 2005, at 3:02 PM, JEAN-FRANCOIS MENARD wrote:
>
> > Hi,
> >
> > I finally did a first prototype of an interface to link two K2/
> > KPA100 on one multi-band HF antenna using Don W3FPR schematic. For
> > my first "from scratch" project, it is not too bad. I first began
> > to do a PCB. I used two fast SPDT 16A relays from Omron and SO-239
> > connectors are Amphenol.
> >
> > I will try it tonight.... But on the bench test, everything was
> > working fine... Maybe I will need to put a few caps to filter some
> > RF, I'm not sure.... I will tell you later tonight. This is my
> > first prototype version... My « main goal » is to have a interface
> > like this one, but also one mic and one paddle for 2 radios.
> >
> > Unfortunatly, I forgot to take picture of my PCB. But I will put
> > Don's schematic on my website this week.
> >
> > Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html
> >
> > 73
> >
> > P.S. Many thanks to Don W3FPR for his help. ;-)
> >
> > =============================================
> > /¯\/¯\/¯\/¯\/¯\/¯\ JEAN-FRANCOIS MENARD
> > V A 2 V Y Z
> > \_/\_/\_/\_/\_/\_/
> >
> > FISTS #11896
> > Elecraft K2 #4130
> > Elecraft KX1 #999
> >
> > http://homepage.mac.com/jfmenard
> > =============================================
> >
> >
> >
> > _______________________________________________
> > 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
>
>
> -Jack Brindle, W6FB
> =======================================================================
>
>
> _______________________________________________
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>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.362 / Virus Database: 267.13.4/175 - Release Date: 11/18/2005
>
>

JEAN-FRANCOIS MENARD-3

Re: 2 radios, 1 antenna... finally a prototype!

Ho ! Thank to Jack also. I was't know... :-( ;-)

Check this one...

I put my K2 on one connector and my FT-817 on the other. I found
something interresting.... When I have my K2 on 80m and my FT-817 on
40m, everything is OK. But when I put my FT-817 on the same band or
on a band lower than 80m... i.e. 160M, I loose approx. 3db on receive
on my K2.

I checked this with XG1 oscillator.... When indicating S9 on my K2,
when I switch the FT-817 on the same band, I loose 1 S unit on the K2
instantly....

Any idea ?

Le 05-11-19 à 21:23, Don Wilhelm a écrit :

> Yes folks, Jack and I collaborated on the design of this one. I
> started
> with a few logic gates, and Jack kept saying 'do it with no active
> devices -
> anyway, you can see the result in Jean-Francois website and judge for
> yourself.
>
> Since Jean-Francois gave me credit in his posts, I thought I should
> pass
> along extra credit where it is due, and Jack deserves it.
>
> BTW, if I ever get both my K2s to the operating position instead of
> one in
> th eworkshop and the other for operating, I will be using this
> arrangement
> myself - not fully SO2R, but a reasonable compromise suitable for my
> operating.
>
> 73,
> Don W3FPR
>
>> -----Original Message-----
>
>>
>> There is one important step in the construction of the circuit that
>> should make it work well.
>>
>> Now it is important to take this step...
>>
>> What is the step?
>>
>> Contact W6FB in the Phone Sweepstakes - I need the VA2 QSO!
>>
>> :-) :-) :-)
>>
>> Good luck making it run. Don and I had fun collaborating on that
>> one...
>>
>> On Nov 19, 2005, at 3:02 PM, JEAN-FRANCOIS MENARD wrote:
>>
>>> Hi,
>>>
>>> I finally did a first prototype of an interface to link two K2/
>>> KPA100 on one multi-band HF antenna using Don W3FPR schematic. For
>>> my first "from scratch" project, it is not too bad. I first began
>>> to do a PCB. I used two fast SPDT 16A relays from Omron and SO-239
>>> connectors are Amphenol.
>>>
>>> I will try it tonight.... But on the bench test, everything was
>>> working fine... Maybe I will need to put a few caps to filter some
>>> RF, I'm not sure.... I will tell you later tonight. This is my
>>> first prototype version... My « main goal » is to have a interface
>>> like this one, but also one mic and one paddle for 2 radios.
>>>
>>> Unfortunatly, I forgot to take picture of my PCB. But I will put
>>> Don's schematic on my website this week.
>>>
>>> Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html
>>>
>>> 73
>>>
>>> P.S. Many thanks to Don W3FPR for his help. ;-)
>>>
>>> =============================================
>>> /¯\/¯\/¯\/¯\/¯\/¯\ JEAN-FRANCOIS MENARD
>>> V A 2 V Y Z
>>> \_/\_/\_/\_/\_/\_/
>>>
>>> FISTS #11896
>>> Elecraft K2 #4130
>>> Elecraft KX1 #999
>>>
>>> http://homepage.mac.com/jfmenard
>>> =============================================
>>>
>>>
>>>
>>> _______________________________________________
>>> 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
>>
>>
>> -Jack Brindle, W6FB
>> =====================================================================
>> ==
>>
>>
>> _______________________________________________
>> 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
>>
>>
>> --
>> No virus found in this incoming message.
>> Checked by AVG Free Edition.
>> Version: 7.1.362 / Virus Database: 267.13.4/175 - Release Date:
>> 11/18/2005
>>
>>
>

Vic K2VCO

Re: 2 radios, 1 antenna... finally a prototype!

In reply to this post by JEAN-FRANCOIS MENARD-3

JEAN-FRANCOIS MENARD wrote:

> I finally did a first prototype of an interface to link two K2/KPA100
> on one multi-band HF antenna using Don W3FPR schematic. For my first
> "from scratch" project, it is not too bad.
<snip>
> Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html

The only thing that bothers me about this circuit is that if the Amp Key
output from either K2 is disconnected for any reason, transmitting on
the other one will put RF into the front end of the first one.

I thought of several ways to make the circuit fail-safe with a few logic
gates, but I'll leave it to the real circuit designers to suggest the
best way. I would suggest using the 8r signals from the K2s in addition
to the amp-key output. The 8r is on in receive mode, and you could
arrange things so that unless either an 8r signal or amp-key ground is
present, that K2 will always be connected to the dummy load.

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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Vic K2VCO

Re: 2 radios, 1 antenna... finally a prototype!

Vic K2VCO wrote:

> The only thing that bothers me about this circuit is that if the Amp Key
> output from either K2 is disconnected for any reason, transmitting on
> the other one will put RF into the front end of the first one.

I *should* have said: if the amp-key output of radio 1 is disconnected,
transmitting on radio 1 will put RF into radio 2...and vice versa.

And it's very easy to forget to plug something in, I do it all the time!

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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JEAN-FRANCOIS MENARD-3

Re: 2 radios, 1 antenna... finally a prototype!

In reply to this post by Vic K2VCO

I know Vic. Another way to do it, will be to supply both relays to
receive. So if no Amp key present or no 12V, or... By default, it
could be connected to a dummy load....

There are many ways to do this, with different danger level....

Le 05-11-19 à 21:40, Vic K2VCO a écrit :

> JEAN-FRANCOIS MENARD wrote:
>
>> I finally did a first prototype of an interface to link two K2/
>> KPA100 on one multi-band HF antenna using Don W3FPR schematic.
>> For my first "from scratch" project, it is not too bad.
> <snip>
>> Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html
>
> The only thing that bothers me about this circuit is that if the
> Amp Key output from either K2 is disconnected for any reason,
> transmitting on the other one will put RF into the front end of the
> first one.
>
> I thought of several ways to make the circuit fail-safe with a few
> logic gates, but I'll leave it to the real circuit designers to
> suggest the best way. I would suggest using the 8r signals from
> the K2s in addition to the amp-key output. The 8r is on in receive
> mode, and you could arrange things so that unless either an 8r
> signal or amp-key ground is present, that K2 will always be
> connected to the dummy load.
>
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco

Don Wilhelm-3

RE: 2 radios, 1 antenna... finally a prototype!

In reply to this post by Vic K2VCO

Vic,

Such fail-safe mechanisisms can certainly be devised if deemed necessary.
The 8R signal mentioned is actually the inverse of the Amp-Key line, so that
signal can be produced with an inverter and no additional connections to the
internals of the K2.

One of the goals was to do the job with no active devices, and such
fail-safe mechanisms were not considered.

One of the ways to accomplish such 'fail-safe' operation is to inhibit
keying (or PTT) until all other conditions are properly satisfied, but the
problem with that solution is - it requires some kind of external stimulus
to initiate the transmit state for the K2 (i.e. the chicken and the egg
controversy). If one inhibits the paddle and PTT inputs to the K2, that K2
will never enter the transmit state and activate the Amp-Keying signal - the
only way to make that work is to accept an external 'start' input, such as a
footswitch or other similar input. The CW PTT circuit on my website
http://w3fpr.qrpradio.com does exactly that task and could be used if such
safety features are deemed necessary.

73,
Don W3FPR

> -----Original Message-----
>
> JEAN-FRANCOIS MENARD wrote:
>
> > I finally did a first prototype of an interface to link two K2/KPA100
> > on one multi-band HF antenna using Don W3FPR schematic. For my first
> > "from scratch" project, it is not too bad.
> <snip>
> > Take a look... http://homepage.mac.com/jfmenard/PhotoAlbum55.html
>
> The only thing that bothers me about this circuit is that if the Amp Key
> output from either K2 is disconnected for any reason, transmitting on
> the other one will put RF into the front end of the first one.
>
> I thought of several ways to make the circuit fail-safe with a few logic
> gates, but I'll leave it to the real circuit designers to suggest the
> best way. I would suggest using the 8r signals from the K2s in addition
> to the amp-key output. The 8r is on in receive mode, and you could
> arrange things so that unless either an 8r signal or amp-key ground is
> present, that K2 will always be connected to the dummy load.
>
> --
> 73,
> Vic, K2VCO
>

Vic K2VCO

Re: 2 radios, 1 antenna... finally a prototype!

Don Wilhelm wrote:

> Such fail-safe mechanisisms can certainly be devised if deemed necessary.
> The 8R signal mentioned is actually the inverse of the Amp-Key line, so that
> signal can be produced with an inverter and no additional connections to the
> internals of the K2.

Amp-key is derived from 8r and is in some sense the inverse of it, but
neither 8r not amp-key are high/low outputs. They both have one state
which is indistinguishable from 'disconnected'. If you use amp-key by
itself you can't distinguish between these situations:

1) Amp-key output is open and the K2 is receiving; and
2) Amp-key output is accidentally disconnected and the K2 is transmitting.

8r by itself can't distinguish between

1) 8r is open and the K2 is transmitting; and
2) 8r appears open (accidentally disconnected) and the K2 is receiving.

So I suggest adding logic *inside* each rig to assert a signal (called
'safe') only when 8r is on or amp-key is not grounded. Then you would
connect safe and amp-key to the interface. The interface would connect
rig 1 to the antenna only when rig 2 is asserting safe and not grounding
amp-key, and vice-versa.

Now let's see what happens when things get disconnected. If you
disconnect rig 2's safe line, rig 1 will always be disconnected from the
antenna. If you disconnect rig 2's amp-key then safe will still go low
when rig 2 transmits (because of the logic inside rig 2), disconnecting
rig 1 from the antenna. And vice versa.

Of course, then you would have to turn on both K2s to listen to either
one of them. I am still trying to figure out a way to avoid this without
losing the fail-safe nature of the system!

> One of the ways to accomplish such 'fail-safe' operation is to inhibit
> keying (or PTT) until all other conditions are properly satisfied

I think the complications/limitations that this introduces are worse
than turning on both radios!

--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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Don Wilhelm-3

RE: 2 radios, 1 antenna... finally a prototype!

Vic,

What you say is certainly true - it does take two redundant signals to
provide a fail-safe mechanism that includes one of the signals being
disconnected. We all must examine the exposures and weigh them against the
risks of using simpler, but less protected solutions. There is a compromise
in there somewhere, and each implementer must make his own decisions based
on his own risk assessments.

As we used to say in my engineering group - 'You can endeavor to make it
foolproof, but then some 'fool' will still break it'. Your level of risk
acceptance is uniquely yours - do whatever is needed to produce a risk level
that is acceptable to you.

73,
Don W3FPR

> -----Original Message-----

>
> Don Wilhelm wrote:
>
> > Such fail-safe mechanisisms can certainly be devised if deemed
> necessary.
> > The 8R signal mentioned is actually the inverse of the Amp-Key
> line, so that
> > signal can be produced with an inverter and no additional
> connections to the
> > internals of the K2.
>
> Amp-key is derived from 8r and is in some sense the inverse of it, but
> neither 8r not amp-key are high/low outputs. They both have one state
> which is indistinguishable from 'disconnected'. If you use amp-key by
> itself you can't distinguish between these situations:
>
> 1) Amp-key output is open and the K2 is receiving; and
> 2) Amp-key output is accidentally disconnected and the K2 is transmitting.
>
> 8r by itself can't distinguish between
>
> 1) 8r is open and the K2 is transmitting; and
> 2) 8r appears open (accidentally disconnected) and the K2 is receiving.
>
> So I suggest adding logic *inside* each rig to assert a signal (called
> 'safe') only when 8r is on or amp-key is not grounded. Then you would
> connect safe and amp-key to the interface. The interface would connect
> rig 1 to the antenna only when rig 2 is asserting safe and not grounding
> amp-key, and vice-versa.
>
> Now let's see what happens when things get disconnected. If you
> disconnect rig 2's safe line, rig 1 will always be disconnected from the
> antenna. If you disconnect rig 2's amp-key then safe will still go low
> when rig 2 transmits (because of the logic inside rig 2), disconnecting
> rig 1 from the antenna. And vice versa.
>
> Of course, then you would have to turn on both K2s to listen to either
> one of them. I am still trying to figure out a way to avoid this without
> losing the fail-safe nature of the system!
>
> > One of the ways to accomplish such 'fail-safe' operation is to inhibit
> > keying (or PTT) until all other conditions are properly satisfied
>
> I think the complications/limitations that this introduces are worse
> than turning on both radios!
>
> --
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco