[Elecraft] Connecting a BigIR

Sun Mar 16 23:04:39 EDT 2025

See below...

> On Mar 16, 2025, at 8:40 PM, Ted Edwards W3TB <w3tb.ted at gmail.com> wrote:
> 
> Hi, Everyone.  I am really glad to see this thread.
> I am currently preparing to put up a BigIR here at W3TB in Tennessee.\
> 
> I should have ordered the "Y" Cable with the purchase -- I did order the S26 Cable, but it is not right in that I have a P3 panadapter along with me K3.  The K3 does have the upgraded I/O Board and panel.  I am now trying to buy one but having trouble getting a response from the SteppIR folks. Maybe they are away traveling to a hamfest somewhere.  
> 
> I probably have a wrong idea here, but looking at page 12 of the KI03B literature where it shows the connections on the back of the P3 makes me think that I could just run the S26 cable from the "computer" back connection on the P3 to the SteppIR control box to get the frequency information to the control box.  In any case, I would rather do the "Y" Cable if I can get one.

You don’t want to do that. The signal has to go back to the KIO3B in order to complete the connection to the USB interface. In other words, if you break the connection, the K3 will no longer talk to the computer.
You really need the Y cable. 

73,
Jack, W6FB

> 
> This has all been very informative in the thread, and I thank you all for it.
> 
> On Sun, Mar 16, 2025 at 2:11 PM Jack Brindle via Elecraft <elecraft at mailman.qth.net <mailto:elecraft at mailman.qth.net>> wrote:
>> Sometimes we type the wrong key; Andy busted my call (W6FB), but I know he meant to type the right number.
>> 
>> As for the SteppIr discussion, I am curious. For those who control a SteppIR from a K3 or K4, how well does it work in split mode? The best test would be for a SteppIR that does 40 meters where split mode operation is common. Since the K3 only sends the Rx frequency in the IF command, you should see “High SWR” on transmit of the Tx frequency is far away. The test would be rx on something like 7120, Tx on 7290. You could try the same test on 10 meters where you could get farther apart frequency-wise, but split mode is seldom used on 10, except for repeater operations.
>> 
>> One other observation - this issue would not happen with a K2, which sends the VFO B frequency in the IF command while transmitting in split mode. In split mode, the K2 receives on VFOA and transmits on VFOB. Life used to be so much simpler...
>> 
>> 73,
>> Jack, W6FB
>> 
>> 
>> > On Mar 16, 2025, at 1:18 PM, Andy Durbin <a.durbin at msn.com <mailto:a.durbin at msn.com>> wrote:
>> > 
>> > I had an interesting off-list email exchange with Jack, W7FB.  That caused me to run a test on a KX3 that I am borrowing.  My tests indicate that a KX3 does not change the frequency encoded in the IF word for the RX/TX transition.  It continues to send the RX frequency.
>> > 
>> > The programmer's reference says
>> > 
>> > "IF (Transceiver Information; GET only) RSP format: IF[f]*****+yyyyrx*00tmvspbd1*; where the fields are defined as follows: [f] Operating frequency, excluding any RIT/XIT offset (11 digits; see FA command format)".
>> > 
>> > It seemed a reasonable assumption that operating frequency meant RX frequency when RX and TX frequency when TX just as implemented in the Kenwood IF word.  It appears that it does not work that way so I'm baffled as to why there is a reference to XIT if only RX frequency is encoded.
>> > 
>> > If my test was valid, and K3/KX3/K4 only send RX frequency in the IF word, then these rigs will not have the same issue with a SteppIR controller as the Kenwood rigs.  The SteppIR controller will never know the Elecraft TX frequency and will only track the RX frequency.
>> > 
>> > Educational for me but maybe a waste of bandwidth for everyone else.  Sorry about that.
>> > 
>> > 73,
>> > Andy, k3wyc
>> > 
>> > 
>> > 
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> 
> 
> -- 
> 73 de Ted Edwards, W3TB and GØPWW
> 
> and thinking about operating CW:
> "Do today what others won't,
> so you can do tomorrow what others can't."