3.4 GHz Transverter Conversion (3.5 GHz WiFi transceiver)

[VK3PK]

I have attached the Arduino sketch that gives you control of both PLL's, silences the beeper if PLL2 removed.
It will be moved onto the GARC website with the other docs.
At present it does not have the alignment beeper installed, which I will do in due course.
Incidentally PLL2 currently runs at 448 Mhz. so it is right at the band edge of the IF, not 460 Mhz as it may have been suggested..
Lee VK3PK

[VK5TX]

Two of my friends in vk2 are looking at having a play. Is there anyway of getting two of these to Newcastle?

Sent from my D5833 using Tapatalk

[VK3ALB]

Hi VK5TX,

If your friend is Josh he has already contacted me and will be picking some up from us in the next 2 weeks.

[VK5TX]

Thanks

Sent from my D5833 using Tapatalk

[VK3KIS]

I got 3 panels a few months back and managed to brink one of the panels. Can anyone help getting it working again please?

Using version 1 of the documentation I got 55mW out of the transverter. The problem I am having is the IF has a very high SWR into the panel which is part of the problem. I am about to remake the 2 boards again but my hands are not wanting to plan. Has anyone etched a board? If no are there plans to?

73,

Andrew (VK3KIS)

[VK3ALB]

Hi Andrew,

I replied to your request for help some time ago but I guess you didn't receive my reply. Perhaps check in your spam folder for messages dated the 24th of Jan?

Thanks for your interest in our project. I'm responsible for the creation of the manual so I'm always happy to receive comments regarding the content. You also reported some issue with the receiver modification but I didn't get any details. If you can reply here it may help others.

As for the input VSWR I can tell you the original panel featured in the manual has an input VSWR of 2.2:1 as does my own panel and others have reported similar readings. There is no doubt that the dead bug construction approach will have a lot to do with the VSWR as the TX path is not a 50 ohm transmission line but due to the power levels involved there should be no problem. My FT817 does not even hint at a VSWR problem and I'm quite sure a hand held is capable of transmitting into almost anything you offer it.

One approach you might like to investigate to reduce the input VSWR is increasing the input attenuator from 3dB to say 6dB or 10dB. This will produce a lower VSWR at the expense of some RX gain. If you do choose this path I recommend you add a receive preamp to compensate for that loss. A Gali-39 kit from MiniKits should be adequate. Another avenue you might like to investigate is using the MiniKits sequencer kit rather than the IF and DC boards. Just make sure the board fits under the cover.

You didn't explain why you thought your panel was damaged by the input VSWR to the IF board. From bitter experience I can tell you that one sure fire way to kill the PA is to drive it into an open circuit. I've done that twice due to a dodgy connection on the output relay board. The supply current generally rises to over an amp in this situation and the 5V reg output is shorted to deck. I've also got one panel that is quite low in gain and manages about 500mW tops. I've tried replacing the PA chips on failed panels but I don't think I was able to successfully solder the replacements to the ground plane and they failed in quick time.

What are you using to measure the output power?
What is the current draw on TX?
How much signal are you injecting into the input attenuator of the TX?

I can tell you the values given in the manual are very typical. An input of -4dBm at the input attenuator will give a watt out of the PA. Note this test needs to be done BEFORE you connect the IF and DC boards and output relay.

Looking forward to your reply Andrew.

[VK1JA]

Another avenue you might like to investigate is using the MiniKits sequencer kit rather than the IF and DC boards. Just make sure the board fits under the cover.

Hi Lou,

Do you have a suggestions on how/where to wire a minikits sequencer into the panels, for those that won't be using a FT817 etc. The minikits sequencer can be triggered by either RF or PTT which makes it appealing, plus I have a spare kit sitting unused a the moment

[VK3ALB]

Hi Lou,

Do you have a suggestions on how/where to wire a minikits sequencer into the panels, for those that won't be using a FT817 etc. The minikits sequencer can be triggered by either RF or PTT which makes it appealing, plus I have a spare kit sitting unused a the moment

Hi Jayson,

Off the top of my head I think you could use the first delay to switch the output relay and the second delay for TX enable on the board. Don't forget the TX signal needs a series 4k7 resistor.

[VK3PK]

3.4 RX Alignment signal source.
For those that have access to Arduino development tools, here is a slight modification & instruction how to turn a "donor board" into a 3.400 Ghz. signal source, so that you can at least align the RX filters & mixer.
Basically output of PLL1 & PLL2 are mixed in second TX mixer. To change the frequency change PLL2 frequency.
Lee VK3PK

[VK2JDS]

Speaking of donor boards.....

I just had another failure of the tx driver and predriver 3 legged chips. They look like a pga103.
Its the 2 that are under the can that gets removed in the process of tx filter removal on the original donor filter mod.
Does anyone have an idea of what the c018 devices are, or an equivalent, or maybe a cut out of that section of pcb i could procure ?
The 9cm field day on sunday and my only remaining transverter fails, hence a rapid assembly of a spare and a search for these rf devices.

73 Dave

[VK3PK]

Hi Dave,
On one of my donor boards one of the devices is marked CO16, but more interestingly on another board they are both marked G002G, which turns out to be a MMIC - ECG002B-G and that seems to agree with the circuitry on the board. http://www.bdtic.com/DataSheet/TriQuint/ECG002F-G.pdf.
So a Google search with MMIC + C016/18 might get you info on those.

[VK5ZT]

Hi Dave

I reckon a GALI39 would almost be a drop in replacement but would need a different bias resistor. At least they are locally available (Minikits)

As a general comment, I have found these transverter boards are a bit fragile! I have encountered various weird problems, some that I cannot identify a cause for!! (mysterious failures, a shorted track in the middle pcb layer, odd power supply problems, lifting tracks...to name a few).
I suspect some of the panels around were pulled from service due to faults. I had one with a completely dry antenna solder joint...which was open of course! One thing I did notice on one board was a significant voltage overshoot when powering up while the buck boost device settled down!!!

I now have my original panel uploaded with new firmware.....it has a 432 MHz IF and a switch to select old/new bandplan (ie down 2 MHz)

Cheers

Tim VK5ZT

PS...... If you are contemplating having new firmware loaded, don't forget to add the pins for the ISP port...it's the six larger holes near the micro. I fitted two rows of three pins....the snap off ones readily available from Jaycar etc. or in my case, came in the packets with Arduino boards!! Do it anyway while you have the board out...... VK5ZT

[VK3ALB]

Just to add to the knowledge base of these panels - there is no circuit or manual.

These are my personal observations after working on a number of panels for myself and with others. They may help someone.

I have seen two board where the power supply input did not connect to the switching regulator - possibly a broken track in one of the middle layers of the board. My own panel had a jumper wire installed when I took the back cover off.

Average TX output from these panels is around +30dBm (1W) for -4dBm into the modified TX attenuator. However some panels need as much as +2dBm for similar output and some just don't get much past +27dBm (0.5W) no matter how much you put into them.

Don't drive the TX into an open circuit - failure of one or both output devices occurs very quickly indeed. Check your wiring carefully. Failure seems to occur with a short from the PA enable line to GND. The low dropout regulator nearby shuts down because it can't supply the current.

Expect around 1dB insertion loss from the MiniKits relays at this frequency.

I have had one notification of a dead RX where the supply is missing from the mixer chip. I have no more information than that and don't know if that receiver has been repaired.

The middle trimmer on the UHF IF filter board is really important. You need a fine blade to adjust it and when you do you'll see how critical the tuning is. If you're not getting anything out of your RX try giving that middle trimmer a tweak.

While I have made many good contacts with a revision 1 modified board, they could probably all benefit from a bit of RX pre-amplification. The Gali-39 preamp from MiniKits will assist in this regard.

Most panels I have seen are tuned 4kHz to 6kHz high. With a steady hand you can adjust the TCXO to bring them closer to the "correct" frequency. You can of course just keep this in the back of your mind and tune around a bit when looking for contacts. Don't expect everyone to be bang on frequency to you when your dial reads 444.150.00.

The polarization arrow on the inside panel indicates VERTICAL polariztion of the antenna. To operate you panel for horizontal polarisation this arrow should point left or right. Remember you could lose 20dB of signal due to cross polarisation.

[VK5ZT]

Re: Loss of power to the mixer....been there, done that...don't know why it happened!

In my case it was the series diode that drops the 6 volt supply down to around 5.5 (mixer's max supply volts).
The diode actually looks like a transistor but has the two leads on one side bridged...it goes high or open and no more volts!!

It is near one corner of the mixer box on the end nearest the edge of the pcb, from memory.

Hope this helps...

Cheers

Tim VK5ZT

[VK3ALB]

Thanks Tim, I think this is the bad boy. A very easy component to lose when removing the shields too!

Dropper diode for 1st mixer supply.

[VK2KYP]

HI all,
My Panel was working very well until yesterday afternoon, Tx power output +30dBM and I could hear -120dBm.
Now the board draws about 1.5 amps and now difference between TX and RX.

I suspect short circuit PA MMIC's

I used my version of Dave 2jds receive modification using a pipe cap filter between RF stages of the filter, using 1 pipe cap filter my image rejection on
2512 MHz was 25db down

I will report back to confirm if the PA MMIC's are short circuit

73 Gary vk2kyp

[VK2KYP]

Hi All,
Can someone please bring some panels to the Wyong field day?
please message me
Thank you

73 Gary

[VK3BQ]

GARC / lou has a table at the emdrc Hamfest Sunday in Melbourne and tells me he will have some panels to sell, if you are in melbourne, come and get them sunday http://www.emdrc.com.au/ for more information.

[VK3QI]

Further to Andrew's post about some panels being available at the EMDRC White Elephant sale on Sunday.

Some have asked how to up the power output once you get the taste for 3.4 Ghz. On Sunday I will have a number of Toshiba UM2683B amplifiers for sale on my table plus a selection of suitable SMA relays for switching purposes.

If you are not aware of the Toshiba UM2683B amplifiers (nominally 20 watts output) , and how they can be converted to give up to 60 watts output have a look at: http://www.kl7uw.com/DL7YC-3400.pdf

With the A$ having fallen significantly in the last 18 months, the cost of importing these and other 3.4 ghz amplifiers from USA and Israel has become prohibitive.

Check it out Sunday!

Cheers

Peter VK3QI

[VK3ALB]

Sorry - we've sold out and there are no more panels to be had.

For those that want to get on board with this project I suggest you start asking around as hundreds of these panels went everywhere except VK6 and VK8. In the early days we were shipping in lots of three with the intention that one be sacrificed for parts to complete the remaining two. I know many people have not started their conversions so depending on your negotiating skills you may be able to liberate a panel from a ham near you.

We will keep updating the documentation on our website as new information arrives and of course we'll be having another activity day on the 25th of April.

Thanks to all of you that have purchased panels, posted here about their experiences and written to our club. Revenue from this project will help fund the replacement of the roof of our clubroom and the purchase of an air conditioner to keep us comfortable during the weather extremes.

This project has brought many people together and the collaboration has been fantastic.