[Elecraft] KX3 Computer Interface for digital modes

[Igor Sokolov]

Jim,
Nowadays  even SO stations are much more complicated then just transceiver 
and linear amp. There are filters, RX antennas, power splitters in stacks 
which need to be controlled and require additional delays. 8ms is very often 
not enough to compensate for all the delays. I had to build small circuit 
that makes use of  inhibit signal in  my K3 to extend rigid 8 ms built into 
K3 although it would be more logical to have programmable TX delay built 
into the transceiver. For SO2R the problem is even more complicated because 
of the need for lock out. Now think of MS station with 4 or 5 ops sharing 
antennas and amps and using lock out. How would they do with just 8ms or 
worse QSK only TRX?


73, Igor UA9CDC

----- Original Message ----- 
From: <k3ndm at comcast.net>
To: <jim at audiosystemsgroup.com>
Cc: <elecraft at mailman.qth.net>
Sent: Sunday, July 29, 2012 11:24 PM
Subject: Re: [Elecraft] KX3 Computer Interface for digital modes


> Jim,
> Yeah, I knew that there was a problem with many of the amplifiers. I just 
> don't know how pervasive the problem is. I know Tentec and a few others 
> have a way to deal with the problem. And, I just haven't needed to deal 
> with the issue since I was playing with 10KW amplifiers when I was working 
> for TMC down in Virginia more than 40 years ago. I knew there was a reason 
> I didn't want to go high power. ;-)
>
> I totally forgot about the preamp switching problem. That too is something 
> that I haven't needed to deal with in a lot of years. Way back when, most 
> of us used preamps just ahead of our downconverters. There were a few 
> smarter hams around who figured out the the transmission line from the 
> antenna to the preamp was adding dramatically to the noise figure. It was 
> they who started to mast mount their preamps; it was the same crowd that 
> used the noise figure equation and were smart enough to know that line 
> loss = negative gain. It's terrible to get old and forget those early 
> lessons.
>
> 73,
> Barry
> K3NDM
>
>
> ----- Original Message -----
> From: "Jim Brown" <jim at audiosystemsgroup.com>
> To: elecraft at mailman.qth.net
> Sent: Sunday, July 29, 2012 3:56:28 AM
> Subject: Re: [Elecraft] KX3 Computer Interface for digital modes
>
> On 7/28/2012 9:36 AM, Barry LaZar wrote:
>> The real issue is amplifier turn on timing.
>
> And the switching of relays for mast-mounted preamps used in serious
> VHF/UHF stations.
>
>> As I don't use an
>> amplifier as QRO to me is a 100 Watts. I can't address the issue from
>> experience. However, I suspect that there is an easy fix since all high
>> power users face the same issue, particularly on CW.
>
> But it is NOT an issue for ALL those who use power amps, it is an issue
> for those who use badly engineered power amps with slow relays! It is
> NOT an issue for my me with my good quality Ten Tec amps, designed c.a.
> 1980, which use good vacuum relays, nor with my Elecraft amp, nor, I
> suspect, is it an issue with most Alpha and ACOM products.
>
> The problem is with CHEAP amps -- ever look inside an Ameritron? -- and
> with home builders playing it CHEAP. Example: I recently posted asking
> about build quality of relay switching systems for antennas, and more
> than half of the replys included phrases like "you can use so and so's
> much CHEAPER relays" and "so and so's system is much cheaper." Mom and
> Dad were both accountants, but they also taught me the difference
> between quality and junk, and when it was worth spending ENOUGH to do it
> rignt.
>
> Now, the nature of some relays is such that fast switching is not
> consistent with good RF performance, and I suspect that the high quality
> coax relays that Lance and others are talking about to switch preamps
> and to switch 2M and higher power amps are inherently not that fast.
> But for conventional ham power amps at HF, decent relays ARE fast enough
> to switch with the delay times provided by rigs like the K3 and
> FT1000-series.
>
> 73, Jim K9YC
>
>
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