2.4 GHz Amplifiers for Es'hail-2

Latest News and Discussion about the use of the DATV transponder on Es'hailsat 2
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2.4 GHz Amplifiers for Es'hail-2

Post by G3VZV » Sat Aug 04, 2018 5:00 pm

I have, in my garage, an unmodified Andrew UMTS amplifier that is referred to in an article in Scatterpoint back in 2013
http://www.microwavers.org/scatterpoint ... t_1303.pdf
Just wondering if anyone else has any experience with modifying and using these for DATV? Also wondering which other amplifiers might be available/suitable for use when Es'hail-2 is activated.
thanks and 73
Graham G3VZV

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Re: 2.4 GHz Amplifiers for Es'hail-2

Post by g0mjw » Sat Aug 04, 2018 5:45 pm

Hi Graham,

Unfortunately, while good, that article missed out a lot of the information that was available at the time. There seemed to be a rush to publish quickly rather than checking what was out there already, which was a lot, including schematics.

I wrote an article on modifying these using an Arduino Nano to provide diagnostics and protection.
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However, these amplifiers are for 2.1 GHz and going to 2.3 GHz, without modification of the RF matching was already pushing it. Going up to 2.4GHz is maybe pushing too far, untested. That does not mean it won't work, but it is likely to work a lot better with some retuning. The good news is they run off -48V so you can use a standard telecoms supply, but also the internal system is 28V which might be better as the existing PSU is a limiting factor for CW output. If you want to operate well backed off for DATV, its fine as it is. I also have a spare in my garage.

Meanwhile, there are other options - Stealth Microwave do a range of highly linear amplifiers and people will be very familiar with the 20W 3.4GHz units with the purple heatsinks that were widely available surplus a year or two ago. So available I remember the box containing 2 of them, with PSUs were going for £5 to £10 at Didcot last year. There were also 50W units but these were much rarer.
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Anyway, they also made identical looking amplifiers covering 2.4 GHz. The trick to identification is to understand the model number - e.g. SM3437-43 is an amplifier covering 3.4-3.7GHz at 43 dBm (20W). The SM2325-47 covers 2.3-2.5GHz at 47 dBm (50W) and there is a 44dBm (25W) model. They do appear, from time to time at Rallies and on Ebay.

This forum does not allow PDFs to be uploaded but google SM2325-47 should come up with the info.

There are quite a few other options but I would try to modify your Andrew PA first.


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Re: 2.4 GHz Amplifiers for Es'hail-2

Post by G8PEF » Sat Aug 04, 2018 8:30 pm

Graham's post, and the link to the Scatterpoint article reminded me that buried deep on my desk at work I have one of the ILAM modules, which (IIRC) is good for 120W (voice modes), albeit requiring about 22A at 28V to do it.

Does anyone have any idea as to whether this would make a good candidate for Es'hail-2? If so, what sort of o/p power do you think I could realistically get out of it for TV modes?

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