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Monday, 18 June 2018

Splashing Complete

Well,

Following my recent post back here about my bonkers SPE 1.3K-FA Amplifier, I thought I should post an update now it's back from its short vacation in Italy.

It has been back to the factory for three issues:

  • Front Panel missalignment
  • Very noisy fans
  • Attenuator fittment

So, I am please to report all three issues are sorted on the amplifier and the drive levels, whilst still somewhat bonkers, are very much more reasonable and within the range that I can actually control from the radio.

Luckily, my main radio (The TS-990) is extremely well thought out, and within the menu system you can set the granularity of the power out adjustment:


So  I can now set the output level exactly as I require on each band.

Here's a quick video of the amplifier now its back:


You can see the automatic band switching working - I have this working on both the Kenwood and my IC-7610 radios - you can also see that 5W drive now gives me 250W and 8W gives me full UK legal limit.

I haven't yet played with the in-line attenuator I made back here, but will do soon.

I've actually used the output from my MicroHam DigiKeyers to drive the CAT control from the rigs, so I can also keep the CAT line into the computer for logging and other control purposes.

All good.

Sunday, 17 June 2018

It's a Kind of Magic.....

Well,

6M AKA "The Magic Band" sometimes simply amazes me.

Today I have worked Cuba, Puerto Rico, Dominican Republic and Haiti.

Here's my all time 6M QSO log as a map:


Amazing, isn't it?



Sunday, 10 June 2018

TS-990 on 144MHz

Well,

Following some discussions at Ham Radio 2018, Friedrichshafen, I've done another example video of the TS-990 with a G4DDK transverter:


There's a document I've compiled on the transverter setup here.

Here's one of the halls full of goodies that I don't need from the rally - it really was very good:


and some of the test gear on offer:


And here is my very lovely Luna cat enjoying a snooze in the shack:


and finally, Miss Florrie Cat:


Good, egh?

Thursday, 7 June 2018

Taming the Amplifer

Well,

Following my recent purchase of an SPE Expert Amplifier I described here, I've been pondering how to keep the amplifier under control. It is currently back at the manufacturer for three issues:
  1. Extremely noisy fans;
  2. Bent front panel;
  3. Attenuation fitting.
I attended Ham Radio 2018 at Friedrichshafen this year and spoke to the owner (Dr. Gianfranco Scasciafratti I0ZY) of SPE while I was there. I tried to explain my concerns about such low drive level requirements and the reliance on ALC and associated risk of failure; the conversation concerned me because he didn't seem to want to listen to a word I said.

SPE have sent a video of my amp under test:


So hopefully it's on its way back to me now.

I've designed a thingamabob to put in-line with the amplifier as recommended by I0ZY to provide attenuation to the input drive level. Gianfranco suggested that the attenuation could be permanently in-line as on receive it "didn't matter". However, I'm not happy with that so I have come up with the following to switch the attenuation in line during TX and remove it during RX:


In reality the build looks like this:


There are quite a few bits in there, there are two coax relays (50 GBP), the connectors and the resistors in the Pi Attenuator (50 GBP) plus the case and other assorted bits and bobs (75 GBP) - so a total of 175 GBP just to tame the amplifier. Of course, I will need two of these if I want to use the amp as designed with two radios. I find it odd that they would recommend such a solution - why not just put sufficient attenuation in the amp to start with?

The gubbins has a good flat response from 0 to 50Mhz and also give us about 6.16dB of attenuation.


Throughout the build construction Florrie Cat has been assisting:


and somehow, you just know it's not going to end well:


Odd situation, don't you think?

Monday, 4 June 2018

Over the pond on 6M

Well,

After many years of trying, FT8 has given me my first QSO over the pond:



I'm rather delighted - it's quite an opening going on:


Good, egh?

Friday, 25 May 2018

Tuning an ICOM

Well,

I've been fiddling lately with external ATUs and most recently the linear I mentioned last time.

More and more I keep wanting an easy way to generate a tune carrier from the IC-7610. Now, when Kenwood designed the TS-990 (the best radio in the world) they got everything right. There is a tune function you can allocate to one of the user programmable buttons, and also you can set the tune power by band - what could be simpler?

Well, with the latest and greatest Icom radio, you have to stick the radio in FM or AM or RTTY, press the Transmit button after adjusting the power to the required level and sticking a chicken down your trousers and facing north. The last bit isn't actually necessary, I was just checking you were paying attention.

So here we have the answer to the problem:

The switch in the middle of the schematic selects the internal or external ATU and the outside switch (in my case a push button) enables the carrier:



The whole thing connects to the external tuner connector on the back of the majority of Icom radios, which I've made a plug for by butchering an old PC PSU connector:


Easy, don't you think?

Thursday, 24 May 2018

Splashing Out Somewhat

Well,

I decided to get myself a new toy. The idea is that this replaces the linear amp, the antenna switching, the radio switching on HF plus the ATU - all in one box. Also it doesn't need to "warm up" or tuning on each band.

So I brought it home, somewhat excited:


Now, I first tried it with my TS-990 as the exciter. The manual doesn't actually tell me anything about required drive levels, but anything from the TS-990 generates "INPUT OVERLOAD" error - even only with 5W output. So more consultation of the manual and it seems they are keen on you using ALC connections to control the exciter drive levels, so I hook up the ALC line and then this is what happens:


Now that's really quite strange.

Next I try the IC-7610, connect up the ALC and PTT lines and it seems to work OK, however, I have very little control over the RF out - in fact I cant get the amplifier to deliver less than just over 500W output even on the lowest power output setting. That's not very clever - I want to be able to control the RF and gain of the amplifier.

So, some email back and forth to the manufacturer and it seems there are two versions of this amp. One for the US market which includes an attenuator in the drive line so that 25-30W of RF is required for full output, and an EU version without the attenuator.

SPE sent me this table which shows the input RF needed for full output by band and power setting (you can have the amp on Low, Med, High):


So at this point I fell off my chair! This amp eneds only 2W of drive on the low bands for maximum output. The only way that low level of drive is possible with most modern transcievers is by using the ALC all the time to restrict the output of the rig - which is exactly how this amp is "designed" to operate. I think the issue with the TS-990 is that despite ramping the ALC voltage to the most -ve it can, the output is still too high to drive the linear.

Either way, there is no way you can set the controls to deliver, say, 200W output. You can have maximum bananas (which seems to be 500W, 1Kw and 1.3Kw) depending on the Low, Med or High selection of the amp power switch.

The manufacturer recommends you run your rig at FULL RF output and rely 100% on the ALC circuitry to protect the MOSFET in the linear from being fried. I personally don't like this theory at all.

Needless to say the amplifier has been returned today for modification to the USA version so I have some hope of controlling the RF output.

Here you see the drive level of 3W:


which produces 508W out in the "low" power setting:


Bonkers, don't you think?