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10GHz update

A while ago I mentioned a possible new 10GHz product that might appeal to SOTA activators. It will be a low-cost transverter (2m IF) and has been designed to be significantly more “plug and play” than current 10GHz gear. It will be capable of working over any line-of-sight path in the UK with a margin using a 20dB horn. The longest LoS path is just over 240km.

I am told that there is now an alpha model working and beta models will be available in a few months. I am hoping to get a SOTA s2s contact with the designer using his alpha model over the next few weeks.

I’ll keep you all posted.

73

Richard
G3CWI

PS the current price of a DB6NT 10GHz transverter is 537 Euros; the DEMI transverter is over $500. These prices are for units that are not usable as they stand but require additional hardware. My friend is aiming for a price of about £200.

In reply to G3CWI:
Very interesting Richard!

Look forward to further info.

73

Jack (;>)

In reply to G3CWI:

My friend is aiming for a price of about £200.

At that price it could look good on the end of my dish! Failing that, anyone up for some WBFM? :slight_smile:

73, Gerald G4OIG

In reply to G3CWI:

Sounds interesting. Is there any idea of the expected output power and input noise figure?

Andy
M0FMF/p

In reply to MM0FMF:

The basic unit will have modest performance. It has been designed as successor to wideband gear; but with significantly better performance than that could ever achieve. It will be proper narrowband gear capable of SSB/CW. The actual design concept is rather clever - being both cheap and effective. Power output will be in the 10s of milliwatts range and RX NF will probably be around 8dB (I am guessing here).

I like the idea so much that I intend building a 4m transverter based on the same concept. That will likely run 100mW with a 6dB NF.

73

Richard
G3CWI

In reply to G3CWI:
I have never ever played on 10GHz. With a price point around £200 I would find it quite tempting to consider having a go. It all sounds very interesting indeed. I will await the future announcement of the product.

Andrew, G4AFI

Further info from my friend:

The basic up/downconverter will generate about 0.1mW, possibly a little more.
The noise figure will be around 12dB. The local oscillator will start with a
1ppm TCXO. A feed for an offset dish is designed and ready to prototype, and
I’ll also make a pre-drilled box available.

A primary aim of this project is to make the transverter very easily
upgradable. I plan to supply built and tested system components which can be
built into a system which can grow with the purchaser’s interest.

The next step will be a board with intermediate amplifiers to ~10mW on transmit
and a noise figure of about 5dB on receive. To go to this level will need a
bandpass filter between the up/downconverter and amplifiers to reduce the
transmit spurious products to an acceptable level and protect the receiver
from potential sources of out-of-band interference.

My plans beyond that are based around a 1.5W+ PA and a 1dBNF front-end.
A better, GPS-based LO reference is also on the cards.

Should anyone query the potential effectiveness of a 0.1mW transmitter, it’s
worth doing some sums!

Let’s use the longest line-of-sight (LOS) path in the UK (240km) as an
example:

The free-space path-loss over 240km at 10GHz is ~160dB.

If the gain of two 50cm diameter dishes (~33dB each at 10GHz) is subtracted
from the free-space loss is subtracted, the power arriving at the receiver
input is ~94dB below the transmitter power.

So with a -40dBW transmitter, we’d see -134dBW at the receiver input.

A 3kHz bandwidth receiver with a 12dB noise figure has a noise floor of about
-160dBW, therefore the received signal/noise ratio will be about 26dB. Of
course, if you use CW, the reduced effective bandwidth will result in even
greater effectiveness!

The basic up/downconverter with a suitable antenna should be capable of
working any LOS path with ease, and to be able to cope with many singly
obstructed paths, particularly on CW. It will also be capable of exploiting a
number of other propagation mechanisms such as tropo ducting, maritime super-
refraction, and even more intense rainscatter. Alternatively, a lower gain
antenna such as a 20dB horn would give good results over any usual LOS path.

Running a similar system back in the mid-1980s, my best DX was 250km during a
tropo opening.

In reply to G3CWI:

Sounds excellent. The Excelics PA blocks (50 ohm in and out so just add volts and bias) require about 7dBm worst case for 30dbm out. The small add on amp would drive one with ease and the Excelics devices are only about 35Eu.

Andy
M0FMF/p

Doing a few more sums, one system to another similar one will give a 6dB s/n ratio on SSB over a 100km path if 20dB horns are used (most likely antenna for SOTA ops). CW will be better (of course). There are a great many interesting paths to try over this sort of range. For example, Snowdon to Shining Tor will work on CW and possibly SSB.

If you are working someone with a more conventional system running 1 Watt and with an RX NF <2dB range will be far better.

73

Richard
G3CWI

In reply to G3CWI:

This is on ebay:

May be of interest to a SOTA activator?

73

Richard
G3CWI

In reply to G3CWI:

The following offering from ADI looks potentially useful for 10GHz and
they have a reputation for handing out free samples if you ask nicely.

http://www.analog.com/en/rfif-components/rfif-amplifiers/adl5606/products/product.html

73

Rick

In reply to M0RCP:

Rick, I just had a look at the data sheet. The graphs of gain and P1dB are heading downhill rapidly at 2670MHz so I don’t think there will be a lot left at 10GHz.

Scattering parameters are given up to 4GHz - the gain drops from 25dB at 1GHz to 7dB at 4GHz.

It would also be a pain to solder - it’s only 4mm by 4mm and it needs a lot of vias underneath and near it to take the heat away!

It’s designed for 1800MHz to 2700MHz so will be great for 13cm though!

Thanks for the pointer - an interesting device.

73
John GM8OTI

In reply to GM8OTI:

Whoops, yes it was 13cm I had in mind. So totally OT.

Rick

In reply to M0RCP:

Ah now that’s promising. Are you up for an attempt at a 13cm SOTA contact sometime? Apart from Robert GM4GUF I don’t know any other activators with 13cm.

Sorry, still OT :wink:

73
John GM8OTI