[Elecraft] K3: data modes - bizarre behavior

Sun Jan 1 17:09:21 EST 2012

Matt,

What does your frequency matrix say for "center of channel" and
what is RMS Express setting for DATA A dial (USB carrier) frequency?

In DATA A, the dial frequency is identical to the USB carrier
frequency.

73,

    ... Joe, W4TV

On 1/1/2012 4:25 PM, Matt Zilmer wrote:
> Thanks, Joe.  I've been with MARS for a few years now and understand
> the "channel center" frequency matrix.
>
> This is a case where the string setting the K3's carrier freq is
> setting the correct value.  There is something odd at work here.
>
> matt
>
> On Sun, 01 Jan 2012 15:47:51 -0500, you wrote:
>
>>
>> Matt,
>>
>>> I verified that the software is setting the correct carrier freq,
>>> based on the center freq cited by the MARS frequency matrix.  I was
>>> thinking along the same lines as your suggestion below.
>>
>> Standard practice in government operation - including MARS in recent
>> years - is to specify the "center of channel" and *not* the USB dial
>> frequency.  The two frequencies will differ by 1400 to 1500 Hz based
>> on the particular assumptions used for the transmitter with 1500 Hz
>> being slightly more common.
>>
>> I suspect you will find your MARS matrix specifies "center of channel"
>> for all digital and any remaining CW networks while still giving USB
>> suppressed carrier frequency for voice networks.
>>
>> 73,
>>
>>     ... Joe, W4TV
>>
>>
>> On 1/1/2012 2:25 PM, Matt Zilmer wrote:
>>> Thanks for your reply, Bill.
>>>
>>> I verified that the software is setting the correct carrier freq,
>>> based on the center freq cited by the MARS frequency matrix.  I was
>>> thinking along the same lines as your suggestion below.
>>>
>>> If I use program control to set the freq, then I get TX + 1.5 KHz =
>>> RX.  This is with split disabled and RIT / XIT turned off.
>>>
>>> Temporarily, I'm manually setting the carrier freq to 1.5 KHz below
>>> center instead of relying on the control program to do this.  That
>>> solved the problem, but doesn't explain why the radio has carrier freq
>>> centered on the freq only under program control.
>>>
>>> Mysteries....
>>>
>>> 73,
>>> matt W6NIA / NNN0UET
>>>
>>>
>>>
>>> On Sun, 01 Jan 2012 13:21:51 -0500, you wrote:
>>>
>>>> Well, this is normal for digital mode DATA A.  I'm not familiar with your
>>>> particular software, but for PSK31 and similar modes, the K3 VFO A is set to
>>>> a frequency for the carrier.  The audio is on the upper sideband, and is
>>>> centered in the 3 KHz passband which is 1.5kHz up from the carrier.  Thus
>>>> the offset.  Some digital software has an allowance for an offset, but I'm
>>>> not sure about yours.  You might check on this.
>>>>
>>>> Typically if operating on 20 meters with radio set to 14.070MHz, the
>>>> waterfall will be full of traces at audio frequencies spread across the
>>>> passband of your radio.  So you actual transmission freq is the sum of VFO
>>>> plus the audio.
>>>>
>>>> ...bill  nr4c
>>>>
>>>> -----Original Message-----
>>>> From: Matt Zilmer [mailto:mzilmer at verizon.net]
>>>> Sent: Sunday, January 01, 2012 11:31 AM
>>>> To: elecraft at mailman.qth.net
>>>> Subject: [Elecraft] K3: data modes - bizarre behavior
>>>>
>>>> In all this time with K3 #24, I've never been stymied by any issue
>>>> such as described below.
>>>>
>>>> I'm a Navy-Marine Corps MARS member.  We use RMS Express in the WL2K
>>>> system on HF, running WL2K Winmor mode  The software I have is version
>>>> 1.1.3.0.
>>>>
>>>> I also use LP Bridge to create two COM ports: one used for DTR (PTT)
>>>> and the other for control, COM19 and COM20 respectively.  The sound
>>>> card is an EMU 0202.
>>>>
>>>> The problem is this:  When RMS Express takes control of the K3,
>>>> calling an RMS node on HF *always* results in the receive frequency
>>>> being 1.5 KHz too high.  I've had to rotate the RIT between call-up
>>>> transmissions to get the RX on frequency before the initial 5 attempts
>>>> time out.  The TX frequency seems dead-on, because the RMS always
>>>> answers - but RX is 1.5 KHz high.  And yes, I've tested with multiple
>>>> RMS nodes, including my own NMCM RMS here at the shack.  Same problem
>>>> occurs with each, so it's a setup issue with software or the K3 here.
>>>>
>>>> RMS Express sends the following commands after it's set the COM20 comm
>>>> parameters:
>>>>
>>>> 	FR0;	# cancel split
>>>> 	RT0;	# RIT OFF
>>>> 	XT0;	# XIT OFF
>>>> 	MD6;	# TX DATA mode
>>>> 	DT0;	# DATA A sub-mode of TX DATA
>>>>
>>>> The sequence above is sent once at the beginning of an RMS Express
>>>> call-up of the remote node.  Only COM19's DTR is used to assert PTT
>>>> for transmissions.
>>>>
>>>> Just for grins, I checked the various meta-modes the K3 is in.  I
>>>> discovered that even though AI is set to ZERO, I'm still getting IF
>>>> annunciations back from the K3.  Odd, that.
>>>>
>>>> 	K31;	# K3 extended commands enabled
>>>> 	K22;	# K2 extended " "
>>>> 	AI0;	# AUTOINF OFF
>>>>
>>>> Since split and the incremental controls are off and ZEROed, I'm
>>>> totally blind to what's going on.  VFO A is on the correct frequency
>>>> in each case (for each RMS Node), which means to me that RX and TX
>>>> actual frequencies should be the same.
>>>>
>>>> Any ideas what's causing this?
>>>>
>>>> 73 and HNY,
>>>> matt W6NIA, NNN0UET
>>>>
>>>>
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