Search This Blog


Saturday, 11 April 2015

Transverting - Finished!


You may remember the 4M transverter I started making here:

I mentioned that I was waiting for a zlpll from here:

to complete the project.

Well, it arrived today and I have installed it in the tranverter:

Marc, ON5VW was kind enough to offer me an on air test, so this is my signal as received in JO10 over the water in Belgium:

So that's the final proof of concept - all working as planed!

Good, egh?

Wednesday, 8 April 2015

Transverting - Complete!


The 4M Transverter I started back here:

Is now **nearly** complete.I say nearly as I am still waiting for a ZLPLL board from here.

The interior has been completed and all wiring completed, here's a shot mid way though that process:

Now, you may remember that I have a Gemini 4M & 6M amplifier. Well, this was configured for a 25W drive level when I bought it, so I needed to modify it for the lower drive level of this transverter. The amplifier includes an attenuator which needed to be replaced. Here's a view of the Gemini with the covers removed:

In the photo above I have highlighted with a red circle the component that needed to be replaced. You can hopefully see that I have also had to remove the internal covers from the RF board screened enclosure to access the part.

Here's the RF board with the new attenuator installed:

This is working beautifully from the transverter now and giving me full power out from the transverter drive levels.

Good, egh?

Thursday, 2 April 2015

Transverting - Even More More!


Following from the start of the 4M Transverter project I posted about last time:

I've done some more today.

The power amp module is built and mounted on the rear of the enclosure with an aluminium heat spreader:

The rest of the enclosure is prepared:

The internal wiring is almost complete, I've just run out of SMA cables - which is a bit of a bummer! I'm also waiting for the ZLPLL from here to complete the project properly.

Not a bad start though, egh?

Transverting - Even More!


Following the success of my 2M transverter project back here:

which I showed off working here:

I decided that I would like to have a bash at making one of these transverters for 4M. Sam, G4DDK agreed to supply me with a kit of parts for a 4M variant of the Anglian. There are about 40 or so component changes. This meant that the board needed the SMD soldering to complete the unit - the 2M version required no SMD soldering!

So here is the project in it's infancy:

And here with quite a few more components in place:

and here with it complete and in the tin screening box:

I've run all the basic tests and both the RX converter and TX converter are working fine. There is a 42MHz local oscillator (70 - 42 = 28) - as with the 2M variant, I have ordered a ZLPLL board from here:

to provide an external frequency reference to stabilise the on board LO.

I've started the PA board to go with the unit; it should deliver about 7W output.

I've decided that to avoid any switching between transverters I will leave the 2M box interfaced to the TS-990 and use this 4M variant with the FT-DX5000. That has a transverter output which is -10dBm rather than the 0dBm I require. I may have to experiment a little with the levels but I should be able to drive the 4M Gemini amplifier perfectly with this combination.

Let's see.

Freddy cat has been doing a fine job of being almost completely in the way throughout.

Local conditions.

Tuesday, 10 March 2015

My SWRs got no nose - How does it smell?


You may recall the 6 Element LFA 2M Yagi I installed back here:

plus the masthead amplifier I built and installed back here:

There has been something very strange indeed going on with this antenna. Here's the evidence as I see it:

  • The SWR varies - not while in use, but sometimes it's not as good as it was when I left it!
  • It is either good or bad, I have never seen it go from good to bad while in use;
  • When it's bad the Gemini linear trips with high SWR (which is good)
  • The bad SWR does seem to be more present when it's cold
  • When it's bad the SWR seems to be about 1.8:1
  • Having had the antennas down many times to look at this problem, the only thing I am suspicious of is a "back to back" N-Type connector that's up in the air. Everything else seems OK to me.
When I installed the pre-amp, I didn't want to hard wire it in so it was a permanent installation - I therefore decided to hard wire it to the cable tail that connects to the antenna, and fit an N-Type connector to the other lead from the pre-amp. This other lead is connected to the Westflex 103 that feeds back to the shack by means of a "back to back" N-Type plus the N-Type fitted to the end of the Westflex - got it?

So - the connectors are all expensive (not that this means they are good quality, but they look good to me) and they are compression fittings. No amount of wiggling these connectors will make the SWR change. 

I have concluded that the only thing that might be causing my problem is the back to back N-Type connector. To remedy this I have purchased a Female N-Type in-line connector which I can fit to the end of the pre-amp tail, thus eliminating the need for the back to back connector. 

Today I brought the  antennas down and found that by adjusting the 2M antenna, I could reduce the SWR further than it was when I started. Now, due to my suspicions, this was the return loss trace from the 2M beam last time I finished fiddling with it:

So, according to this I had an SWR of 1.55:1 last time I finished with the antenna, after my fiddling today, today my AA-170 analyser is saying this:

which is a return loss of 22.68 dB and an SWR of 1.16:1. My return loss bridge on the spectrum analyser is saying this:

which is that the return loss is 22.12dB and an SWR of 1.17:1 - which is pretty damn close to the analyser or perhaps the AA-170 is close to the SA. What I am trying to say is that the results are astonishingly similar!!

This suggests that I hadn't adjusted the antenna properly when I finished with it last time - perhaps I just got bored? Who knows!

I haven't fitted the female N-Type and will wait and see what, if anything changes going forward. If I have any recurrence of this jumping SWR the pre-amp will have to come down and the female N-Type connector fitted.

Odd, egh?  

Thursday, 5 March 2015

TS-990 on 2M 144MHz - no way!


I've also created this video this morning showing the TS-990 being used with my homebrew transverter for 2M from here:

and the masthead amplifier from here:

All works rather fantastically, even if I do say so myself!

This is a video receiving the GB3VHF beacon on the TS-990:

Local conditions.

Meteor Scatter with the TS-990 - Are you sure?


Fiddling around in the shack this morning and I thought I would share with you a video of the TS-990 being used in conjunction with Gemini 4 linear for Meteor Scatter in JT6M mode.

Local conditions.