VK Logger Ham Radio Forum Archive

That is an interesting observation Peter, the bg7tbl gpsdo designs all seem to run the 10MHz output though a buffer chip, and through that same chip is the 1PPS output. hence why the 10 MHz has a slight modulation of that 1 Hz signal. It is noticable on my signals on 47GHz upwards. Running the Isote...

More testing : The original small OCXO it was supplied with doesn't have enough output to drive the PLL and still have enough voltage to drive the phase detection circuit on the pcb, so it wont lock. I am not using the noisy buffered signal at the socket on the pcb, but connecting directly to the OC...

I can confirm the experiment locking the Isotemp does work and solves the phase noise problem. Next is to test a Trimble brick OCXO and then the Blileys. To fix the as-suppled GPSDO : I suspect that removing the supplied OCXO, powering it from 5 volts from a separate linear regulator then applying t...

Hi Peter, that is the exact pcb thats in the case in the photo i put up but mine doesnt have a vectron in it. Its not real great, same as the green pcb one. The noise looks like it is coming from the pcb rather than the OCXO. To do the Isotemp test I did this: Remove the OCXO. To feed in the 5 volt ...

Cheap GPSDO Pcb experiment to lock an Isotemp. I removed the Bliley OCXO from the green pcb unit pictured in the earlier post. After shifting the internal adjustment of the Isotemp to give a centre of lock range of 2.5 volts to be spot on frequency i connected it to the cheap GPSDO pcb. I didnt even...

As you can see the more expensive ebay unit does a good job and is nearly as good as the Isotemp. For about a hundred dollars more than a cheapy these are the easiest option. With a 10 MHz splitter they can feed several transverters. The cheaper units will probably be suitable for the low bands as t...

Our objective is to have a GPS locked Local Oscillator feeding our transverter/mixer block so when we are working out in the field trying to find a weak station on the other end of a long path we know exactly what frequency his similarly locked signal will be on. (then we just have to aim !) So what...

20190529_142204.jpg 20190526_114649.jpg As you can see from the spectrum analyser screenshot the carrier level above the noise hump is not good at all. and it was the same for both of the tested units. Now lets look at exactly the same test setup using an ISOTEMP 10 MHz oven controlled oscillator. ...

Chinese GPSDO units on ebay are cheap and look good, but how do they perform for us on the higher microwave bands. I have been struggling to get some of the under 200 dollar units to work on my 122GHz gear and similar problems on 76 , 47 and 24. So, whats the problem ? Close-in noise right next the ...

Hi Adam, thanks for the reply, and re the subtle coding changes its a bit above me... i can change frequencies but not much further than that. When you get time then i will be interested to get some prods in the right direction. I had hoped someone had a working template i could just edit for the 76...

Further progress. I found some 14M code on Adam vk4ghz site that runs the si4133D chip, which is the same as on the V2 vk2xdk pll. Tried version 4 and 5. After editing the line picaxe 14M , changing it to picaxe 14M2 it still wont work. run out of ideas to make this go.... the pll runs fine with the...

Tim sent the older pcb V1 code, so i am still on the lookout for the V2 pcb code if anyone has it,
Thanks

Hi All, I have one of these boards and need to change the frequencies.
Does anyone have the pic code handy they could share. It doesnt appear anywhere on the web.
73 Dave vk2jds
Vk2jds@hotmail.com

I dont like the sound of the problem you have identified Brian. We never use them here. Older types used a transformer with a switch setting which tap was applied to the coil in the blanket. These days as has been suggested if the unit is connected to the mains and employs a scr to chop the mains up...

Just clarifying the rx fiter removal method i use. A small oxy/gas CIG torch on a low gas fine point blue flame aimed right in the middle of the filter will quickly release it from the pcb. It provides sufficient heat to release The main earth substrate join, while allowing the pins to soften nicely...

Hi Jayson, closely examine the way you have soldered in your rx filter, there is a chip component nearby and if you accidentaly removed it when getting rid of the old rx filter then that would give the symptom you have. i think the track goes inside the pcb and across into the preamp. If you cant fi...

Any vk2 activity planned by anyone?
its a long drive to the sydney basin for me, so will save the diesel money if no one will be on air.
73 Dave

Yes it was a great afternoon after a very interesting Gippstech. At the sunday lunchtime pizza munchathon I was chatting to Peter Freeman vk3pf and he was exhausted after all the work and had to head home asap. Thanks very much Peter and the crew for the great weekend ! The experience Mark had with ...

Well, Steve vk2kfj, Steve vk2xde, Gary vk2kyp, Roger vk2zrh and myself have our panels here at Gippstech and are looking for expressions of interest in activating 3.4ghz sunday arvo. Are any vk3's available, eg vk3mat, vk3amb or any others? We can listen 147.225 repeater 73 Dave vk2jds Edit : We had...

Aldi has them again and the xyl VK2XPH picked up one for me. Very good thing !
And only $60.
The illumination is bright and the lens is good. I do pcb work and have always used a fluoro tube type of maggy lamp, but this I would recommend.
It draws only 5 watts too
73 Dave