Halve freq gen's 800-960MHz?

[Lou Mathews]

I have a Marconi FM signal generator, model TF 2013, that was designed
for cell phone testing. The frequency range produced is 800-960MHz.

Can someone tell me how feasible it would be to halve the above range
to 400-480MHz, perhaps by bypassing one of the mutiplier stages?

I would suppose that replacing the cystal may cause problems in other
parts of the circuit.

I don't have a circuit diagram at this stage, but can get one
depending on the concensus here.

Or perhaps I can find it by poking around with a DFM.

Thanks for any suggestions.

Lou

 

[Leon Heller]

I have a Marconi FM signal generator, model TF 2013, that was designed
for cell phone testing. The frequency range produced is 800-960MHz.

Can someone tell me how feasible it would be to halve the above range
to 400-480MHz, perhaps by bypassing one of the mutiplier stages?

I would suppose that replacing the cystal may cause problems in other
parts of the circuit.

I don't have a circuit diagram at this stage, but can get one
depending on the concensus here.

Or perhaps I can find it by poking around with a DFM.

Thanks for any suggestions.

Most Marconi signal generators (I've got a couple of 2019As) use PLL
synthesisers, with a VCO running at the output frequency. Changing the
frequency range would involve a lot of redesign work, it's probably not
worth it. You could just use a flip-flop on the output, if a square wave is
suitable for you.


Leon

 

[Andrew Holme]

Most Marconi signal generators (I've got a couple of 2019As) use PLL
synthesisers, with a VCO running at the output frequency. Changing the
frequency range would involve a lot of redesign work, it's probably not
worth it.

The 2019A uses a doubler for 520 - 1040 MHz.

 

[Don Pearce]

I have a Marconi FM signal generator, model TF 2013, that was designed
for cell phone testing. The frequency range produced is 800-960MHz.

Can someone tell me how feasible it would be to halve the above range
to 400-480MHz, perhaps by bypassing one of the mutiplier stages?

I would suppose that replacing the cystal may cause problems in other
parts of the circuit.

I don't have a circuit diagram at this stage, but can get one
depending on the concensus here.

Or perhaps I can find it by poking around with a DFM.

Thanks for any suggestions.

Lou

I would suggest that instead of halving, you mix the output with an
oscillator at 1200MHz. This will drop the output range to 400 -
560MHz, but with all modulation settings maintained intact.

d

Pearce Consulting
http://www.pearce.uk.com

 

[Don Pearce]

I would suggest that instead of halving, you mix the output with an
oscillator at 1200MHz. This will drop the output range to 400 -
560MHz, but with all modulation settings maintained intact.

d

Pearce Consulting
http://www.pearce.uk.com

Oops! Excuse my crap maths - head definitely not on straight. Mix with
an oscillator at 1360MHz for signals from 400MHz to 560MHz, but
remember to invert the modulation.

d

Pearce Consulting
http://www.pearce.uk.com

 

[Fred Bloggs]

I have a Marconi FM signal generator, model TF 2013, that was designed
for cell phone testing. The frequency range produced is 800-960MHz.

Can someone tell me how feasible it would be to halve the above range
to 400-480MHz, perhaps by bypassing one of the mutiplier stages?

I would suppose that replacing the cystal may cause problems in other
parts of the circuit.

I don't have a circuit diagram at this stage, but can get one
depending on the concensus here.

Or perhaps I can find it by poking around with a DFM.

In that frequency range, something like this would be cheap, assuming
you can't modify the 2013:
View in a fixed-width font such as Courier.



-----
| |
800-960 >-+------------------| mxr |-------+
| | | ----
| ---- |splt|
| | ----
| | | | ---
| ----- | +--|BPF|--> out
| 400-500 | vco | | ---
| ----- |
| | |
| | ----
| | | x2 |
| | ----
| | |
| ---- | |
+--| phi | --- | -+-
| |---|LPF|----+ |BPF|
+--| det | --- -+-
| ----- |
| |
+-------------------------------+

 

[Fred Bloggs]

In that frequency range, something like this would be cheap, assuming
you can't modify the 2013:
View in a fixed-width font such as Courier.



-----
| |
800-960 >-+------------------| mxr |-------+
| | | ----
| ---- |splt|
| | ----
| | | | ---
| ----- | +--|BPF|--> out
| 400-500 | vco | | ---
| ----- |
| | |
| | ----
| | | x2 |
| | ----
| | |
| ---- | |
+--| phi | --- | -+-
| |---|LPF|----+ |BPF|
+--| det | --- -+-
| ----- |
| |
+-------------------------------+

Should be this:
View in a fixed-width font such as Courier.


----- ---
800-960 >-+------------------| mxr |-----|BPF|
| | | ---
| ---- |
| | |
| | ----
| ----- |splt|
| 400-500 | vco | ----
| ----- | |
| | | +----> out
| | ----
| | | x2 |
| | ----
| | |
| ---- | |
+--| phi | --- | -+-
| |---|LPF|----+ |BPF|
+--| det | --- -+-
| ----- |
| |
+-------------------------------+