Re: Future KX3/KX2 accessories

[Brian D. Comer]

As some additional insight into the care needed when working with some of
the most popular USB interfaces.

I have recently been  working on understanding the lack of sensitivity in a
900 MHz ISM device. This device is controlled by an FTDI245RQ USB interface.
The clock for this device can be an internal 12 MHz oscillator or a 24 MHz
external oscillator. The internal oscillator has very poor phase noise and
its 76th harmonic, present on the USB data lines, is strong enough to
de-sense a 900 MHz RX over a 7 MHz wide band. The DE0-Nano FPGA development
board which has a similar USB controller but with an external 24 MHz clock
also radiates significant energy on the 38th harmonic of its clock.




Message: 5
Date: Thu, 30 Mar 2017 10:12:21 -0700
From: Walter Underwood <[hidden email]>
To: Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] Future KX3/KX2 accessories?
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=utf-8

Thanks for confirming my guess.

I remain amazed that serial connections are used so much in amateur radio.
Outside of amateur radio, I?ve used RS-232 connections once since the early
1990?s. In 2002, I connected a console to an HP-UX to rebuild the kernel and
get it on our net. I threw away all my RS-232 connector building stuff a
decade ago. Then I got into amateur radio.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Mar 30, 2017, at 8:32 AM, Matt Zilmer <[hidden email]> wrote:
>
> Hi Walter,
>
> In the K3S, we could move the KIO3B digital electronics to the upper
section of the main board, far away from the RF board.  The main board is
also a multi-layer type, so we could sandwich most of the noisy digital
signals between signal ground planes, shielding them pretty effectively.
This solved the problem of digital noise getting into the K3S rx.  In the KX
radios, digital noise would be in close proximity RF boards, so that
opportunity is not available to us.
>
> 73,
>
> matt W6NIA
>
>
> On 3/30/2017 7:58 AM, Walter Underwood wrote:
>> That was my single complaint with the KX3, even before I bought mine. My
current setup is a rats nest of wires.
>>
>> On this list, five years ago, Elecraft said that the USB chips were too
noisy to be inside the radio. I presume they found a way to deal with that
for the K3S, but they have more room to work with there.

>>
>> wunder
>> Walter Underwood
>> [hidden email]
>> http://observer.wunderwood.org/  (my blog)
>>
>>
>>> On Mar 30, 2017, at 4:03 AM, Peter Pauly <[hidden email]> wrote:
>>>
>>> USB Audio. Should have been in the radio from the beginning,
>>> especially the
>>> KX2 since it's new.
>>>
>>> On Thu, Mar 30, 2017 at 2:42 AM, Karl DK5LP <[hidden email]> wrote:
>>>
>>>> My greatest wish:
>>>> A schematic for the KXPA100/KXKAT100.
>>>>
>>>>
>>>> vy 73 de
>>>> Karl-Heinz, DK5LP /  AK5LP
>>>>
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> --
> Matt Zilmer, W6NIA
> www.elecraft.com
> Office: 831-763-4211 x125
> Mobile: [phone]
> [Shiraz]
>
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