Remote PTT for SGLabs Transverter

[VK2BLS]

Hi, in an effort to maintain the ongoing life of Logger Forums, here is a small 'Show & Tell' contribution.

I recently completed my 13CM Spectrian amp upgrade based around an SGLabs transverter/FT817 and the 'PyroJoe' 30W amp board (eBay).
Big thanks to info from VK2.. VK3.. VK4.. VK5.. VK7.. etc who all had valuable info posted on this Forum of their 23/13/9CM etc. projects and tests to refer to for guidance.

I got the 12V, 30W version (actually 25W @ 2.4) going initially located in the shack with a 20 metre run of LMR400 to the 1M dish, mounted on my balcony. Lots of loss at 13CM.
In an effort to reduce coax loss, I decided to relocate the PA/Tvrtr unit closer to the dish. Mounting the PA box at the dish was not on. Mounting under the eve was possible, but it gets hammered with Wx from the west.
I compromised and mounted it just inside the lounge room wall, abt 3.5M coax from dish. The SGLabs transverter can operate from VOX which is fine at 2W, but not ideal driving a PA.
The SGLabs transverter can be internally selected for VOX, PTT or VTT to operate Tx. I already had it set for 'hard line' PTT in the shack, but needed to remotely PTT the PA.
By selecting VTT you can operate the SGLabs Tx remotely with +12V through the coax instead of running a 12V PTT cable to the PA box.

I found a 'cheap' Bias Tee on eBay that works a treat. The FT817 'ACC Mini Din' output plug gives you a (TX GND) pin closure to earth when you PTT.
I pick up a mini 12V relay and then send +12V through the Bias Tee to the SGLabs for PTT Tx.

73 Darrell vk2bls

[VK4RF]

Many thanks Darrell. Gives me a few ideas to work with here also.

[VK7HH]

Excellent work Darrell. Job well done and good idea.

What coax are you using from the transverter to the antenna? I can't quite tell in the photo. Perhaps picking up some scrap LDF-450 would be possible with a couple of N connectors. 5 metres of this is only about 0.6dB of loss. Alternatively LMR400 would be around 1dB and slightly more flexible.

73
Hayden

[VK2BLS]

Hi Hayden,

The grey junction box previously housed my 13CM SGLabs Tvrtr. I use a custom built length of LMR400 + N connectors ordered from 'Times Microwave', (excellent quality).
The short length of LMR400 connects via N:SMA patch leads in the weatherproof JBox, then the SMA's fit through a 'smallish' hole in the wall to the PA/Tvrtr box inside.
The LMR400 connects directly to the dish N connector, flexes nicely when rotating the pole and was easier for me to cope with than a rigid cable.
I relocated the 13CM SGLabs out of the JBox, but the clamps hold the dish and IF cables secure and no need for w/proof wrappings of connectors inside the box.

73 Darrell
vk2bls

[VK7HH]

Nice work Darrell.

Good to see a bit of interest on the 13cm band recently too, good stuff.

[VK2BLS]

Keep the Forums going...

My FT817 does not have an accessory socket like my FT100D, where I can get a hard wired PTT from the rig while utlizing the Data & ACC Mini Din sockets for something else. On the FT817 You can pick up (tx gnd) & (gnd) pins from the ACC Mini Din to use for external PTT, which I did with a h/brew patch cable.

This was fine when using my trusty Signalink for digi modes as it does not need the ACC socket. However, a problem arises when you wish to use the ACC socket to connect to a PC or other Interface etc. as I found when I wanted to connect my 'U5 LINK' back up........ You can't plug in the patch cable as well! So, I have made up a little inline 'breakout box', where I can access the (tx gnd) & (gnd) pins again. Then I can connect the PTT line back into my Bias Tee box for remote PTT.

73 Darrell
vk2bls

[VK3ALB]

Hi Darrell,

Good job on pulling this all together. If you don't mind getting inside your radio with a soldering iron you can simplify your installation somewhat. You do away with your external bias tee and build it into your radio. Once you've modified your radio the comport problem goes away as you no longer need a breakout box.

If you think this is something you might like to try, have a look at my QRZ page and see the FT817 bias tee modification notes.

[VK2BLS]

Thanks Lou, good tip and link, would be a cool mod.
73 Darrell