How to decode when signals over load JT65-hf ? - JT65-HF

The old Google Groups will be going away soon, but your browser is incompatible with the new version.
Message from discussion How to decode when signals over load JT65-hf ?
Received-SPF: pass (google.com: domain of k5oai....@gmail.com designates 209.85.214.176 as permitted sender) client-ip=209.85.214.176;
Message-ID: <4F92CCDC.6050...@gmail.com>
Date: Sat, 21 Apr 2012 10:06:04 -0500
From: Sam Morgan <k5oai....@gmail.com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:11.0) Gecko/20120327 Thunderbird/11.0.1
MIME-Version: 1.0
To: "jt65-hf@googlegroups.com" <jt65-hf@googlegroups.com>
Subject: How to decode when signals over load JT65-hf ?
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

I thought I would share a trick I found this morning
and ask how others deal with overloading.
Maybe program overloading is the wrong term?

Here is an example of I am referring to...

I saw a JA calling CQ so I start trying to answer him
his signal is showing as a +1 in JT65-hf's audio
and the report it is later going to send him is -19

after 4 attempts to answer him I QRO from 5w to 20w
hoping maybe the extra 6db will bring me up out of his noise
great, now he is answering me with my signal report of -20
I send him his report of -19
and then when it's his turn to respond with an RRR

205 cycles down someone comes on, that is so strong,
they send JT65-hf up into the red with readings over 8
and instead of seeing 7-8 different decodes
JT65-hf is so overloaded it doesn't decode anyone

disabling multi and switching to single bw of 20
still doesn't help, no one decodes,
if I reduce the volume I might lose the JA altogether
and I can't get it reduced enough anyway

on a whim, I took a chance and turned on the K3's NOTCH filter
and tune it to where most of the strong signal is notched
I can't vary the width but I can manually vary the center frequency
so I covered the left side and maybe 60% of the rest of his signal
now JT65-hf is back reading down around 2-3

(the strong signals were still causing the floor to rise
2-3 points above where it was before)

and I was able to receive the JA's RRR
and later his 73 to complete the exchange
that was a close one, I almost lost him,
had he not stuck around and kept sending
while I tried to fiddle with everything.......



OK here was my operating situation:

the attenuator was already in and the RF gain on the K3 was already down
as low as it can go and still get enough of signals I want
(I've tried this with the RF maxed and letting the AGC do all the work
and also tried it like this, the slightly reduced rf gain seems the best)

I have tried turning down the volume of the sound card (SignaLink USB)
but it seems if I get the volume down where JT65-hf isn't in the red
I often have already lost the signal I wanted to decode

maybe reducing the bandwidth to focus on only the station I want,
but by the time I get the filter narrowed down and shifted over
it may or may not take out the problem station, so that's iffy

hint: no matter which way I pointed my vertical
the fb and side rejection failed to sufficiently reduce
the signal strength of the 'offending' station
so that won't work for me, j/k

So, my question is what tips and tricks do others use
to deal with signal over loading in JT65-hf,
so you can decode the signals you want,
other than going to a different band? ;-/


-- 

GB & 73
K5OAI
Sam Morgan
Create a group - Google Groups - Google Home - Terms of Service - Privacy Policy
Account Options
