Thanks for the info, Tim.
Maybe I am being too conservative with the -3 dB on the ALC, but I do not want
to put out some of the "garbage" that I sometimes see when listening to JT-65
signals. A setting on the VAC TX gain of -1 dB would not put out anything close
to 100 watts on my rigs, so apparently it a characteristic of JT65-HF. I have
copied Joe Large, developer of the program, for some input (no pun intended!).
Ed, K0KC
________________________________
From: Tim Ellison <t.m.ellison...@gmail.com>
To: flexra...@yahoogroups.com
Cc: Ed Wilson <ed.wil...@ymail.com>; Dave Beumer WØDHB <d...@w0dhb.net>;
"Flexradio@flex-radio.biz" <Flexradio@flex-radio.biz>
Sent: Thursday, October 20, 2011 4:50 PM
Subject: Re: [Flexradio] VAC and JT65-HF
Your PA is fine.
The amount of drive is dependent on the AF gain being fed from the
digital mode program. If it is not putting out 0 dB, then a VAC
TX gain setting of 0 dB will not produce very near 100 watts PEP
with a tone.
You ALWAYS want to use DIGx modes for digital mode operation
because it bypasses all of the voice signal processing (EQ,
compander, leveler) that can adversely effect the AF generated by
the digital mode program.
You also NEVER want to exceed 0 dB on ALC, as this is "clipping"
the DSP and that is never good for digital modes. I never exceed
-1 dB to allow for some headroom. With Fldigi, I get 90W out on
PSK31 with the VAC TX Gain = 0
Tim Ellison
On 10/20/2011 3:27 PM, Ed Wilson wrote:
>Dave,
>
>I can get 100 watts out in the tune mode (and CW when I
use that mode).
>
>Ed, K0KC
>
>________________________________
>From: Dave Beumer WØDHB <d...@w0dhb.net>
>To: 'Ed Wilson' <ed.wil...@ymail.com>; Flexradio@flex-radio.biz;
>flexra...@yahoogroups.com
>Sent: Thursday, October 20, 2011 2:48 PM
>Subject: RE: [Flexradio] VAC and JT65-HF
>
>Ed
>
>When I get a chance later today I’ll see the max power I
can get out of JT65 alc -3 drive slider 100 into a dummy
load.
>
>Have you tested your max power out hitting “TUN” and
running Drive to 100 ? Maybe your overall output power is
low.
>
>Dave
>
>From:Ed Wilson [mailto:ed.wil...@ymail.com]
>Sent: Thursday, October 20, 2011 10:39 AM
>To: Dave Beumer WØDHB; Flexradio@flex-radio.biz; flexra...@yahoogroups.com
>Subject: Re: [Flexradio] VAC and JT65-HF
>
>Dave,
>
>Thanks for the hints.
>
>First of all, the dummy load does not make any difference
compared to the antenna since the VSWR is essentially 1:1
with the antenna.
>
>I did try PSK31 using DM780 and I was able to obtain about
50 watts output with the ALC reading -3 dB...I believe
that I moved the slider up to -3 to obtain this reading.
>
>My transmit filter is 0 to 3K, so I do not think that
should be a problem.
>
>Ed, K0KC
>
>
>________________________________
>
>From:Dave Beumer WØDHB <d...@w0dhb.net>
>To: 'Ed Wilson' <ed.wil...@ymail.com>; Flexradio@flex-radio.biz;
>flexra...@yahoogroups.com
>Sent: Thursday, October 20, 2011 12:23 PM
>Subject: RE: [Flexradio] VAC and JT65-HF
>
>Ed
>
>Have you tried to get higher power with other digital
modes ?
>
>I can get 60+ watts out on PSK with Drive at 100, ALC
level of -3 with
>level slider -1 .
>
>Are you certain your xmit filter is not attenuating the
output.. have you
>tested with a dummy load ?
>
>Dave
>
>-----Original Message-----
>From: flexradio-boun...@flex-radio.biz
>[mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Ed Wilson
>Sent: Thursday, October 20, 2011 8:50 AM
>To: Flexradio@flex-radio.biz; flexra...@yahoogroups.com
>Subject: [Flexradio] VAC and JT65-HF
>
>Colleagues,
>
>I have been running JT65A using the JT65-HF software for
the past month or
>so with good results (several hundred contacts with at
least half DX). I
>have a Flex-5000 and I am running PowerSDR 2.2.3 under
Windows 7/32. I have
>set my Drive control to 100 and have adjusted the VAC TX
gain for an ALC
>reading of -3 dB (-6 on the slider control). With these
settings I get from
>25 to 30 watts out, depending upon the band. This power
output is adequate
>for JT-65A, but what if I wanted to run more power? The
only way that I can
>get my power output into the 100 watt range is to do so by
increasing the
>VAC TX gain to a value of at least 0 and then the ALC is
up to +3 dB, which
>probably would create splatter all over the slice of
spectrum set aside for
>JT65A.
>
>Also, any other suggestions for DSP or other settings that
would optimize
>J65A operation with PowerSDR would be appreciated.
>
>Thanks,
>
>Ed, K0KC
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