LF: Re: [rsgb_lf_group] WD2XES WOLF

[Andy Talbot <andy.g4jnt@gmail.com>]

Good news:

Firstly, the LM317 regulators in the PA are, in fact, both safely within their working limits.  One delivers 24V to relays and also pre-regulates the input to a 12V regulator.   At 24V output there is plenty of headroom with 50V, or even a 55V input rail.   The other LM317 supplies Tx/Rx switched  20V, not 12V as I thought, to the TDA2030 driver chip and FET bias supply.

Secondly:

If I use 2 PCs, combining audio to feed the upconverter just needs two resistors and works perfectly.   I did try running Wolf and WSPR-X software on one PC but, not-surprisingly, they can't be persuaded to drive the same soundcard output.   Reconfiguring to use the main soundcard for one of them would upset my settings for future stuff...

Here is a plot taken from eth transmitter output of the Wolf and WSPR signals (the latter is the test tune signal) transmitted simultaneously .   Amplitudes were adjusted to be within a fraction of a dB of each other on a single tone.

I won't do anything for a day or two, but will announce in advance when running this dual mode test

Andy  G4JNT

On 2 March 2016 at 11:42, Andy Talbot <andy.g4jnt@gmail.com> wrote:

My LF Upconverter is a narrow band one with about 400Hz of useable spectrum http://www.g4jnt.com/ThirdMethodUpconverter.pdf   , so if WSPR-15 were placed at, say, 137604Hz at the lower end of its proper allocation,  with WOLF at  137630Hz it could be persuaded perhaps.   Will ponder and think about the best way of mixing them.  And, more to the point, generating them simultaneously.

But....

Priority first really ought to go to undoing the bodges and short cuts on the old Linear LF PA that I did back in the dark ages.   Like feeding LM317 regulators with 50V !   But, to be fair, the old circuit diagram found in the archives here did label Vdd  "28 - 40V" so was probably aware of that issue back then.  

I also noticed that when running it the other night, it rained during the last couple of hours which detunes the antenna slightly.   The resulting reactance caused the PA DC current to increase from 9A to ~13A.  It survived happily enough, but I have no current limiting or automatic overload protection.

Andy  G4JNT

On 2 March 2016 at 10:45, Sgelliston sgelliston@gmail.com [rsgb_lf_group] <rsgb_lf_group@yahoogroups.co.uk> wrote:

 

Can you transmit DSB? 
LSB = WOLF-whatever-speed 
USB = WSPR-15
That would be interesting!
73
steve
G3XKR

Sent from my Xperia™ tablet

---- Andy Talbot andy.g4jnt@gmail.com [rsgb_lf_group] wrote ----