[ICOM] AMP INTERFACE TO 756 PRO II (CONTINUED)

[Larry Benko]

Paul,

I no longer have the 756PRO2 here since I borrowed it from a neighbor 
ham when I made the measurements.  I do have a 756PRO, 746PRO, 765 and 
706mkIIG here.  The last time I measured them the first dot/dash in 
semi-QSK and every dot/dash in full-QSK mode was shortened overall about 
8ms and slightly more on the 706.  The shortening was a constant time 
amount and not dependent on CW speed and I was using an external keyer.  
The Logikey K3 keyer I use has the option K=05 set to extend all CW 
dots/dashes by 5ms.  This was an attempt at a compromise since I operate 
full-QSK only some of the time.  Please let me know if you make any more 
measurements since my measurements did not match yours.  I made the 
original measurements as part of some other measurements and I was 
transmitting 100w into a dummy load and sending a continuous string of 
dot and dashes at 30wpm (dot = 40ms.).  I will try to borrow my friend's 
756PRO2 again and remake the measurements.

73,
Larry, W0QE

paul at w8aef.com wrote:

>
>
> I used my Tektronix 465 dual trace oscilloscope to make my 
> observations. If/when I put the radio back on the bench I will look 
> again but when I made the original observation I concluded that it was 
> in the digital portion of the radio controls, and I don't want to go 
> there.
>
> And the fault was observed while operating into any one of several 
> monoband antennas, 20 wpm cw qsk, Alpha 76 at full power out.  The 
> trouble shooting was done into one of my several dummy loads.
>
> Further, my 761 and 765 did not have this characteristic.
>
> As an aside, how much is the first dit truncated during cw (non qsk) 
> on your PRO2?
>
> de Paul, W8AEF
>
>
> ----- Original Message ----- From: "Larry Benko" <w0qe at bnk.com>
> To: "ICOM Reflector" <icom at mailman.qth.net>
> Sent: Friday, June 17, 2005 11:58 PM
> Subject: Re: [ICOM] AMP INTERFACE TO 756 PRO II (CONTINUED)
>
>
>> Paul,
>>
>> I 100% disagree with you.  I have measured several Icom rigs 
>> (706mkIIG, 746, 746PRO, 756, 756PRO, 756PRO2, 765) and on all radios 
>> both the "SEND" line and the relay precede any RF by 9 to 11 ms. on 
>> key down and both remain active for approximately the same time after 
>> the rf quits on key up.  I have made some postings to this reflector 
>> with the absolute data in the past.  Search on my call to find it.  
>> If you have evidence based on scope measurements (do not run scope in 
>> alt. channel trigger mode) please post it.   My amp is keyed directly 
>> from the send line through a transistor buffer allowing more than 1 
>> radio to key the amp. and have never had any problems.  If you have 
>> problems I would suggest you try the experiment when operating into a 
>> dummy load.  If your problems go away then the problem is RF getting 
>> into the circuit.  While RF might get into the send line a relay is 
>> much more RF resistant.
>>
>> 73,
>> Larry, W0QE
>>
>
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