Topics

Has anyone bought one of these ...........


Neil Smith G4DBN
 

I bought one to see how it works. You need small fingers, but the thing does what is says on the tin. One output port is fixed frequency, selected on the top line, it has a seven-digit entry box and on-screen keypad for entry. The second output port is for the sweep function, there you set start, stop, step size and step period.  You can start and stop the sweep using two on-screen buttons.  It defaults to 100kHz step once a millisecond.  Top end frequency is 4.4GHz as it says. After a decent warmup, it was about 4.4kHz LF at 4.000000 GHz.

Not looked closely, but there is a setting for crystal frequency set at 30MHz, so it might be possible to inject a locking reference.  There is an unpopulated SMA socket location that could be for an external ref or maybe a VCO.  No sign of any documentation at all.

Looking at the noise, it seems to have rather noisy sidebands at -60dBc out to 100kHz, then it falls away fast to the noise floor of my 8562 at -80-ish.  Could be because I am using a USB power lead inverter thingy.  I'll get it on to a clean supply via the power socket instead and see how it compares.  It looks like it has a programming header, and there are four push buttons which do nothing obvious.

The harmonics at sub-GHz frequencies are terrible, it looks like it might be a square wave, with odd harmonics falling away only slowly, so it would need a serious LPF for anything requiring a pure tone.  Above 2GHz, it is much cleaner, and at 3.9GHz, the second harmonic was 60dB down and the third better than 80dB down. 
Output is about 0.5dBm at 200MHz and 2.4dBm at 2GHz, back down to 1.4dBm at 3.9GHz.
Spurs are about -70dBc

I only bought it to use as a signal source for 3.4GHz because my Agilent runs out of puff at 3GHz. Might find a few more uses for it, but it isn't going to replace the E4421B.  I might put it into a box, it is very convenient to use if it is running from a battery.
Neil G4DBN


Mike
 

Hi

No because you have not provided the items name.

73’s

Mike g4wyz


Neil Smith G4DBN
 

Ha, sorry, I thought I'd copied in the question from the original poster (Gordon I think?), my bad. I was talking about:

35M-4.4G ADF4351 DDS RF Signal Generator + TFT LCD Development board STM32F103

http://www.ebay.co.uk/itm/371612229664

Neil G4DBN


GORDONJ REASON <gordonj.reason@...>
 

these dds modules are falling in price too ............... 

On 04 August 2016 at 17:25 "Neil neil@... [ukmicrowaves]" <ukmicrowaves@...> wrote:

 

Ha, sorry, I thought I'd copied in the question from the original poster
(Gordon I think?), my bad. I was talking about:

35M-4.4G ADF4351 DDS RF Signal Generator + TFT LCD Development board
STM32F103

http://www.ebay.co.uk/itm/371612229664

Neil G4DBN

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


 


 


Mike
 

Thank you Neil

Mike G4WYZ