Hello N1BUG,

Friday, November 16, 2018, 3:03:46 PM, you wrote:

> Hi Markus,

> Mine too! I would strongly prefer that every exciter and amplifier
> be linear but sadly that is not the case in my station. The other
> monster in the chase is frequency stability. ;-)

> I do have a SSB HF transceiver and a home built downconverter for LF
> transmitting. I used this for some CW and JT9-1 QSOs. Unfortunately
> it is of no use for slow modes. The converter has a 10 MHz OCXO
> which is very stable but the HF transceiver operating at 10.136 MHz
> has a cyclic thermal drift of about 6 or 7 Hz every time my furnace
> comes on and changes the room temperature! Transmitting, even at low
> power will also cause problems with heat. This is no good at all. I
> could try to put some kind of heater (like a crystal oven) on the
> transceiver's TCXO and try to add some insulation around it. This
> would not be easy due to its location on a large PCB and limited
> space. I doubt I could make it good enough.

> Better of course (and very interesting!) would be to replace the
> TCXO with an external GPS locked oscillator but I do not know if I
> am up to this challenge. It would require some very delicate surgery
> I guess.

> In an ideal world the HF transceiver TCXO would be replaced by a
> GPSDO, the 10 MHz OCXO in the downcoverter replaced by a GPSDO, the
> downconverter rebuilt to be linear, the amplifier replaced with one
> that is linear, and the LO in the SDR receiver replaced by a GPSDO.
> Unfortunately we do not live in an ideal world and probably none of
> that is going to happen. :-)

> 73,
> Paul



> On 11/16/18 9:18 AM, Markus Vester wrote:
>> Hi Paul,
>> 
>> guess my preferred method is a linear SSB exciter which can do
>> all sorts of modes, including specialties like chirped Hell and
>> picture transmissions, or 1-dB stepped power tests. On the other
>> hand with one sitting here this is easily said ;-)
>> 
>> Stefan and Tom have successfully employed a Raspberry Pi, which
>> can produce modulated RF directly on one of it's digital output
>> pins. This has been used for WSPR but I guess it could also make
>> DFCW.
>> 
>> Best 73, Markus (DF6NM)
>> 
>> 
>> -----Ursprüngliche Mitteilung----- Von: N1BUG <[email protected]> 
>> An: rsgb_lf_group <[email protected]> Cc: lowfer
>> <[email protected]> Verschickt: Fr, 16. Nov. 2018 12:34 
>> Betreff: Re: LF: Methods to transmit DFCW
>> 
>> Thanks Andy. I have no proficiency at all in PIC or Arduino 
>> programming. In my younger days I wrote some reasonably complex
>> DOS programs but a lot has happened since then an the old brain
>> isn't what it used to be I'm afraid.
>> 
>> I am not against *trying* to learn but will consider this a last 
>> resort if no more complete or operator friendly system can be
>> found.
>> 
>> 73, Paul
>> 
>> 
>> On 11/14/18 10:42 AM, Andy Talbot wrote:
>>> Depends how proficient you are with PIC or Arduino or Whatever
>>> programming. There are still AD9850 moduiles to be found on
>>> Ebay - that are not completely obsolete or sold-out yet.
>>> 
>>> Write your controller code to switch between two or three (for
>>> DFCWi) frequencies under control of the ON7YD software,
>>> toggling RTS / DTR on a COM port interface (use an FTDI USB one
>>> if necessary)
>>> 
>>> 
>>> www.g4jnt.com
>>> 
>>> 
>>> 
>>> On Wed, 14 Nov 2018 at 11:50, N1BUG <[email protected]> wrote:
>>> 
>>>> I am looking for a better method to transmit DFCW for 2200
>>>> meter QSOs. For my QSO with 2E0ILY I used a QRP Labs U3S for
>>>> the transmitter. This worked very well for DFCW60 when I was 
>>>> transmitting every other night. For any QSO attempts
>>>> involving quick change from RX to TX it would be difficult
>>>> because of the time required to program a new message!
>>>> 
>>>> One possibility would be to modify this method used by N1VF
>>>> for JT9 QSOs with a U3S:
>>>> 
>>>> https://bgelb.github.io/u3s-qso.html
>>>> 
>>>> I am a little concerned about messing up my trusty U3S but I
>>>> may try that.
>>>> 
>>>> It looks like the easy way is the old QRS software by ON7YD.
>>>> This is very interesting but I don't have a suitable
>>>> transmitter. Are there any published designs for DFCW
>>>> transmitters which could be controlled in this way? I wonder
>>>> if parts would still be available? I am guessing these used
>>>> synthesizers which are not current generation any more. :-)
>>>> 
>>>> Any other suggestions?
>>>> 
>>>> 73, Paul N1BUG


Sadly VK3RF has stopped making these, I have had one in my TS-590S for
years and it works great. Disconnect the Trimble Thunderbolt reference
and it reverts to its own TCXO. There may be alternatives...

-- 
Best regards,
 Chris                            mailto:[email protected]