Topics

Tektronix 7L12


hardyhansendk
 

Hi
I am trying to fix an tektronix 7L12 spectrum analyzer!
When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are shown clearly with same offset!.
Have any off you some experience with this spectrum analyzer?
Regards
Hardy


Miguel Work
 

Hi,


Do you have a button that said start / center above frequency indicator?

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de hardyhansendk via groups.io
Enviado el: miércoles, 27 de enero de 2021 7:56
Para: TekScopes@groups.io
Asunto: [TekScopes] Tektronix 7L12

Hi
I am trying to fix an tektronix 7L12 spectrum analyzer!
When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are shown clearly with same offset!.
Have any off you some experience with this spectrum analyzer?
Regards
Hardy







Scanned by McAfee and confirmed virus-free.
Find out more here: https://bit.ly/2zCJMrO


 

On Wed, Jan 27, 2021 at 07:55 AM, hardyhansendk wrote:


When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are
shown clearly with same offset!.
Did you try adjusting the Horizontal Position knob, right side, in the middle?

Raymond


cmjones01
 

On Wed, Jan 27, 2021 at 3:13 PM Raymond Domp Frank <hewpatek@gmail.com> wrote:
On Wed, Jan 27, 2021 at 07:55 AM, hardyhansendk wrote:

When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are
shown clearly with same offset!.
Did you try adjusting the Horizontal Position knob, right side, in the middle?
Also, on my 7L12, the MHz dial is really very approximate: it's
usually within about 20MHz of the correct value, drifting somewhat as
it warms up. Mine might be broken, of course, but it's always been
like that since I've had it. Looking at how the whole thing works, I'm
not surprised: it's just adjusting the front end YIG oscillator and
there's nothing to correct it to a precise frequency. To see the 0Hz
spike at the correct position on the screen, the MHz knob could be set
anywhere between 9970-0030MHz in my experience. Use of the calibrator,
or some knowledge of what frequency you're looking at, is really
necessary.

Chris


 

On Wed, Jan 27, 2021 at 03:29 PM, cmjones01 wrote:


Also, on my 7L12, the MHz dial is really very approximate: it's
usually within about 20MHz of the correct value, drifting somewhat as
it warms up.
You're right of course, Chris, it's not a frequency meter. The specifications mention a readout accuracy of +/- (10 MHz + 1% of the dial readout).

Raymond


 

On Wed, Jan 27, 2021 at 07:55 AM, hardyhansendk wrote:


When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are
shown clearly with same offset!.
Are you using the calibrator (and horizontal adjustment) for setting/calibrating the horizontal position? The DC ("0 Hz") position is not useful for that. Use e.g. 50 MHz and always set dialing CW, since there is some play/hysteresis.

Raymond


hardyhansendk
 

Hi
Yes there are a start and center button
Hardy

-----Oprindelig meddelelse-----
Fra: TekScopes@groups.io [mailto:TekScopes@groups.io] På vegne af Miguel Work
Sendt: 27. januar 2021 14:42
Til: TekScopes@groups.io
Emne: Re: [TekScopes] Tektronix 7L12

Hi,


Do you have a button that said start / center above frequency indicator?

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de hardyhansendk via groups.io
Enviado el: miércoles, 27 de enero de 2021 7:56
Para: TekScopes@groups.io
Asunto: [TekScopes] Tektronix 7L12

Hi
I am trying to fix an tektronix 7L12 spectrum analyzer!
When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are shown clearly with same offset!.
Have any off you some experience with this spectrum analyzer?
Regards
Hardy







Scanned by McAfee and confirmed virus-free.
Find out more here: https://bit.ly/2zCJMrO






--
Denne mail er kontrolleret for vira af AVG.
http://www.avg.com


hardyhansendk
 

Thanks Chris
Yes i guess you are right--it is not a accurate instrument--will try to align the 1 lo.
Hardy

-----Oprindelig meddelelse-----
Fra: TekScopes@groups.io [mailto:TekScopes@groups.io] På vegne af cmjones01
Sendt: 27. januar 2021 15:30
Til: TekScopes@groups.io
Emne: Re: [TekScopes] Tektronix 7L12

On Wed, Jan 27, 2021 at 3:13 PM Raymond Domp Frank <hewpatek@gmail.com> wrote:
On Wed, Jan 27, 2021 at 07:55 AM, hardyhansendk wrote:

When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are
shown clearly with same offset!.
Did you try adjusting the Horizontal Position knob, right side, in the middle?
Also, on my 7L12, the MHz dial is really very approximate: it's
usually within about 20MHz of the correct value, drifting somewhat as
it warms up. Mine might be broken, of course, but it's always been
like that since I've had it. Looking at how the whole thing works, I'm
not surprised: it's just adjusting the front end YIG oscillator and
there's nothing to correct it to a precise frequency. To see the 0Hz
spike at the correct position on the screen, the MHz knob could be set
anywhere between 9970-0030MHz in my experience. Use of the calibrator,
or some knowledge of what frequency you're looking at, is really
necessary.

Chris





--
Denne mail er kontrolleret for vira af AVG.
http://www.avg.com


hardyhansendk
 

Hi Raymond
I use all of them cal-zero dc and external generator--all with same displayed offset frequency--wonder if one can adjust the first lo!
hardy

-----Oprindelig meddelelse-----
Fra: TekScopes@groups.io [mailto:TekScopes@groups.io] På vegne af Raymond Domp Frank
Sendt: 27. januar 2021 16:04
Til: TekScopes@groups.io
Emne: Re: [TekScopes] Tektronix 7L12

On Wed, Jan 27, 2021 at 07:55 AM, hardyhansendk wrote:


When measuring a frquency-say 50Mhz-it is offset on screen--the zero hertz are
shown clearly with same offset!.
Are you using the calibrator (and horizontal adjustment) for setting/calibrating the horizontal position? The DC ("0 Hz") position is not useful for that. Use e.g. 50 MHz and always set dialing CW, since there is some play/hysteresis.

Raymond





--
Denne mail er kontrolleret for vira af AVG.
http://www.avg.com