[Top] [All Lists]

Re: [TenTec] almost OT (involves Omni VI)

To: tentec@contesting.com
Subject: Re: [TenTec] almost OT (involves Omni VI)
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
Reply-to: geraldj@storm.weather.net,Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 14 Dec 2007 11:25:01 -0600
List-post: <mailto:tentec@contesting.com>
On Fri, 2007-12-14 at 07:28 -0600, atrampler@att.net wrote:
> I've noticed that with my Omni VI (opt 3) on 40 meters I will clearly hear 
> key clicks from some stations, with what sound like true keying sidebands 
> when they are stronger than S9+10 or so, and keying with a bug or straight 
> key.  These clicks or keying sidebands can be 5 kHz away and still S9+, and 
> are not nulled by using the 500Hz 9MHz filter.
This can be generated at their transmitter with simply a too rapid rise
and or fall of the keying envelope, or can be generated in your receiver
because of audio generated AGC and the inherent delay of the crystal
filters. PAs that are over driven into class C can enhance clicks too.

To see if its your receiver, or them, back off on the RF gain so your
AGC has little effect. If the clicks disappear, its your receiver and
its fast attack AGC, else its them and they need to do a bit of key
circuit shaping to narrow their signal. One of the Orion complaints last
year was that at lower than full power the rise time was shorter than
set in its parameter. Hence a parameter value that would have been
clean, was not so clean at lower power where the ALC was stopping the
rise before the DSP shaping had all taken place.

> There are some stations where I pick this up even if they are using a keyer...
> So...question 1: can the use of a straight key or bug produce keying 
> sidebands or clicks if good solid contact is not being made (as sounds to be 
> the case in this situation); and
A bouncing contact could make clicks worse.

> Is the Omni VI especially sensitive to the received CW wave form (perhaps due 
> to something in its AGC structure)?

Its been more of a problem in early TT radios.
> I have listened with AGC fast, slow and off...and these keying sidebands 
> and/or clicks are still there.  
> So is it me...or just that many crappy signals on 40 meters?
> Art, K0RO

73, Jerry, K0CQ

TenTec mailing list

<Prev in Thread] Current Thread [Next in Thread>