> Date: Tue, 26 Apr 2005 07:17:50 -1000
> From: Ken Brown <ken.d.brown@verizon.net>
> Subject: Re: [TenTec] cw creation
> To: Discussion of Ten-Tec Equipment
> <tentec@contesting.com>
> Message-ID: <426E77BE.5060107@verizon.net>
> Content-Type: text/plain; charset=ISO-8859-1;
> format=flowed
>
> Sounds like an interesting rig.
>
> If the 1 kHz sine wave has some harmonic content
> (it is not perfectly
> sinusoidal), this rig could generate as many as five
> signals:
>
> 1) the desired signal 1 kHz above the indicated
> frequency
> 2) the second harmonic of the tone generator would
> still be inside the
> SSB filter and would be a signal 2 kHz above the
> indicated frequency
> 3) the "carrier" which should be well suppressed,
> but often is not
> 4) the opposite sideband of the desired signal, 1
> kHz below the
> indicated frequency
> 5) the opposite sideband of the second harmonic of
> the tone generator,
> 2kHz below the indicated frequency
>
> 3, 4, and 5 are supposed to be greatly suppressed if
> the rig is aligned
> properly. Number two depends on the purity of the
> tone generator.
>
> If it is a phasing type SSB rig that doesn't use a
> sideband selecting
> filter, there could be more harmonics from the tone
> generator, each
> another 1 kHz further from the indicated frequency,
> and more on the
> opposite sideband too. Phasing type SSB rigs do get
> out of alignment and
> the opposite sideband rejection gets poorer, as well
> as the carrier
> rejection.
>
> In many cases I think it would be easier to use
> another BFO crystal and
> unbalance the balanced mixer. There are fewer things
> to go wrong.
>
> Yes, using the tone modulated SSB transmitter method
> can be done and has
> been done. This is not exactly "a great many rigs",
> but there are no
> doubt more. Do you know of some more?
>
> >I have an ex-embassy commercial transmitter, the
> Sunair GSE-924 that
> >injects a 1 kHz sine wave while in USB mode to
> produce CW. This is a
> >pretty impressive rig, no cooling fan 30 w AM, 100
> SSB and 100 CW. I
> >have an idea that it was not much used in the CW
> mode. They do warn you
> >that the transmit frequency is 1 kHz above the
> indicated frequency while
> >in the CW mode.
> >
> DE N6KB
The SBE (Sideband Engineers) SBE34 also used a tone
modulator to generate CW.
In their case, the tone modulator was optional and
simply plugged into the microphone jack.
Doug/WA1TUT
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|