LO Board


dave cossar
 

Hi Brian,

 The idea of having it all on the board appeals to me

But , if you look carefully  the new board does not have an input for a voltage ref

reading the feedback  on Banggood I noticed that one guy had problems getting an

accurate  output  and had n error of I KHz.

 

This is one person only?

Dave GM3WIL

 

 


Colin G4EML
 

Regarding the frequency error. Most of these low cost adf4351 boards have a poor stability reference oscillatory keep the cost down. If you need accurate frequencies you will have to either replace this with a better specified TCXO or feed the board from an external reference. 

Colin. 




On 12 May 2019, at 09:21, dave cossar via Groups.Io <davecossar@...> wrote:

Hi Brian,

 The idea of having it all on the board appeals to me

But , if you look carefully  the new board does not have an input for a voltage ref

reading the feedback  on Banggood I noticed that one guy had problems getting an

accurate  output  and had n error of I KHz.

 

This is one person only?

Dave GM3WIL

 

 


Colin G4EML
 

That should of course have read. ...oscillator to keep the cost down...


On 12 May 2019, at 09:39, Colin G4EML <colin@...> wrote:

Regarding the frequency error. Most of these low cost adf4351 boards have a poor stability reference oscillatory keep the cost down. If you need accurate frequencies you will have to either replace this with a better specified TCXO or feed the board from an external reference. 

Colin. 




On 12 May 2019, at 09:21, dave cossar via Groups.Io <davecossar@...> wrote:

Hi Brian,

 The idea of having it all on the board appeals to me

But , if you look carefully  the new board does not have an input for a voltage ref

reading the feedback  on Banggood I noticed that one guy had problems getting an

accurate  output  and had n error of I KHz.

 

This is one person only?

Dave GM3WIL

 

 


Neil Smith G4DBN
 

I bought one of the original versions with the OLED display and found there was a PCB position for a reference input to replace the wobbly and drifty onboard XO.  It was usually within 10kHz or so, but the drift was terrible.  The software wasn't exactly reliable either, but it was cheap.  It felt like a student project rather than a proper commercial design.  Once I fitted the ref input, it was stable, but very noisy compared with an SV1AFN 4351 board.  I had to fit the SMA socket on the underside of the board and remove a link, also I killed the supply to the onboard XO.  I don't have itany more, I hadn't put it in a case and I dropped an SMA lead on the board while it was powered, and the magic smoke came out.  I gave the display board to someone who had a faulty one.

Maybe the software interface has improved now.  It had simple ramp generation but it felt like it needed a few weekends of serious debugging and a bit more UI development.  The ramps weren't easy enough to use to make it a pleasure, but it was sort-of OK as signal for checking out SHF receivers and for antenna alignment.  Lots of harmonics and quite loud at 10GHz.  I could even see harmonics at 24GHz on my specan.

Banggood does seem to have a decent reputation for ultra-cheap but useable machine tooling, they aren't like some of the fly-by-night ebay suppliers. I haven't bought anything electronic from them, but the suppliers I have used via Aliexpress and UTSource have all delivered non-fake devices, and for the higher-value kit, free express delivery in 4-5 days.  The power gasfets I bought for 5.7GHz are full spec and working fine, so I don't think it is fair to generalise about suppliers from the Far East.  There are good ones and those that are less good. The £11 FETs which I use in the DF9IC 23cm 250W PAs are stunning value, full props to UTSource for those.  Also had good devices from Teng Da, although their prices are not exactly low.

Buying from the Far East needs a bit of research and a bit of risk-acceptance.  It is a bit Wild West and there are charlatans aplenty, but also there are some businesses trading on their reputations. Not an investment for Widows and Orphans, as the saying goes.

I still prefer SV1AFN's kit though.

Neil G4DBN

On 12 May 2019, at 09:21, dave cossar via Groups.Io <davecossar=virginmedia.com@groups.io> wrote:

Hi Brian,

  The idea of having it all on the board appeals to me
But , if you look carefully  the new board does not have an input for
a voltage ref
reading the feedback  on Banggood I noticed that one guy had problems
getting an
accurate  output  and had n error of I KHz.


Brian Flynn GM8BJF
 

Hi Dave
Yes the references are not terribly accurate. Even if they are reasoonably stable there is no way of setting them on exactly on frequency
If you want accuracy you will need to arranage an external ref. Looks like that is what the on board SMA is for. Like Neil DBN I have not had any issues dealing with Banggood and have
been happy with purchases from them.  I have used the little 0.96 and 1.3 inch OLED displays on sig gens I have built up out of these and other chips. They are nice and clear and sharp if on the small side!
73s
Brian GM8BJF