[Elecraft] JT65A output power variations.

[Lance Collister, W7GJ]

Hello Rudolf,

I use JT65A all the time with my K3 for 6m EME, and I have always used USB mode for 
it.  I have no trouble with the USB setting...I have never even tried the DATA 
options.  I have the standard 2.7 kHz filter, and set the audio just like I do for 
USB voice.  I make sure to have the ALC fill the 5 bars on the meter, and I use 20 dB 
of compression to make sure that all the tones come up to the proper power levels.  I 
use the LINE IN on the rear panel for my incoming JT65A tones from the computer.

I find the K3 a great rig for JT65A because I can make a flat bandwidth 300 Hz to 
2200 Hz, and decode callers over that entire frequency range.  I usually run JT65A 
with the NB on the first setting (IF NAR 1), DSP OFF and the AGC off.  It is an 
amazing mode because it has 10 dB sensitivity over CW.  Most of the time on 6m EME, 
signals are too weak to hear, but they are nicely displayed on the SpecJT screen and 
decoded on the JT65A screen.

Now that we are at the bottom of the sunspot cycle, the ionospheric propagation is 
very poor.  However, because the geomagnetic field is usually very quiet these days, 
this is the VERY BEST time for 6m EME!  That is why there has been so much growth in 
6m EME over the last year, and there have been such successful DX operations by small 
6m stations using JT65A mode with just a single yagi aimed at the horizon.

GL and VY 73, Lance

hb9ari wrote:
> Hello,
> 
> As i use principally JT65A (snice ~ 2years),
> i've remarked transmit output power variations
> depending where the audio is located in the waterfall,
> as i'm not speaking English, it's difficult to explain correctly;
> if i'm ~ in the middle of the waterfall (~ 1200Hz)
> i get over 3dB in output power variations; for an expected
> 50W output power, between some tones of the JT65A
> modulation, the output level can vary from 20W
> to 60W; if i'm working away from the "middle",
> variations are lower and acceptable but most
> of time, "central" frequencies are used...
> I've always worked with this "problem" as i
> expect some AGC effect by the receiving side...
> I would appreciate to have an explanation
> of this effect.
> 
> Many TNX for an answer.
> 
> 73 QRO de Rudolf, HB9ARI
> 
> PS With the same sound card and software,
> using my "old" FT857 (non D) TX/RX, the
> output power variation is well under 1dB
> until the audio band edges.
> 
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> 
> 


-- 
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8, E51SIX)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: (406) 626-5728
URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11/6m DXCC #815

Interested in 6m EME?  Ask me about subscribing to the MAGIC BAND EME email reflector!