[OZAPRS] Re: 40m Traffic & TX DELAY

Peter Mallett zl2bau at xnet.co.nz
Sun Apr 5 09:00:10 EST 2009


Ray Wells wrote:
> In my early days of running HF for the BBS I experienced some variable 
> results that I attributed to TXD being marginal. Setting TXD to 450mS 
> ironed out that problem and it remains the value I use with The 
> Kenwood TS430, a Tracker Lynx and a couple of Codans.
>
> There is another setting which, although largely deprecated, can prove 
> useful on HF, and that's TXTAIL, the purpose of which is to hold the 
> TX up to ensure the data has cleared the radio. It's like TXD in reverse.
>
> It's certainly still available as an option with KISS TNC's in Linux 
> kernel ax25, and my Baycom USCC> 4, four port internal card has it as 
> well.
>
> Ray vk2tv
>
> Tony Hunt wrote:
>> David. I dont know what others are running but I run 480mS .. I 
>> messed about
>> with TXDelay on 30m a while back with Tiny Trackers and found that 
>> figures
>> closer to 500mS seemed more reliable. I remember some earlier TNC2 
>> firmware
>> for VHF that came out with default Txdelays of 300mS . Surely its 
>> going to
>> be higher as a rule on HF !!
>>
>> I wonder what everyone is running as a rule?
>>
>> Of course it all depends on different radios your running etc etc.. 
>> It also
>> depends on different receivers that others are running and software and
>> squelches etc. Those latter things are all out of your control..
>>
>> I picked some frames up from you on 40m early this morning around the 
>> grey
>> line at 0413 local. The same with ZL4TZE-4 at the same time. So Ive 
>> got 8
>> stations on the heard list so far.
>>
>> Tony Hunt  VK5AH
>>
>> ----- Original Message -----  
>>> Date: Sat, 4 Apr 2009 14:14:08 +1000
>>> From: David and Justine Olsen <davejust at bigpond.net.au>
>>> Subject: Re: [OZAPRS] 40m Traffic & TX DELAY
>>> To: Australian APRS Users <ozaprs at aprs.net.au>
>>> Message-ID: <5DF92CC8-3A97-461B-97F8-2B9C3E37F8F3 at bigpond.net.au>
>>> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
>>>
>>> I have a very short packet, but my Tx delay is 300mS
>>>
>>>
>>> David
>>>     
>>
>>
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>>   
>
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Hi Ray & All,

                    I have always used 500ms for TXDELAY and 100ms for 
TXTAIL on HF and found it to work very well.

If one has trouble with the station at the other end not hearing you all 
the time, try extending the TXTAIL a bit as that usually helps.

The TXDELAY should of course, take in all factors, rig power up of 
transmitter, switching time from RX to TX and the most important things 
like, allowing for a receiving station who may have a commercial rig 
with squelch built in.

There are many factors on HF, propagation being the "unknown" factor.

Regards ..... Peter

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