[amsat-bb] Potential 23cm FM transmitter

Mac A. Cody maccody at att.net
Wed Jan 31 01:46:38 UTC 2018

This is my third attempt to post this message.  It seems that the AMSAT-BB
blocks messages with JPEG attachments.  Below is a Google translation of
the article on the 23cm transceiver inDKARS magazine.


Mac Cody / AE5PH

This month provided by Hans van Alphen, PAØEHG

Nice new transistor for 23 cm PA

Since the beginning of this year NXP has a nice power LDMOS transistor 
in the range for the 23 cm band.
The transistor type: MRFE8VP13350 assumes pre-matched adaptation and is 
designed for industrial, scientific and medical applications. The 
transistor is capable of supplying 350 watts in the frequency range 700 
to 1300 MHz, which is also ideal for our 23 cm band.
With a typical LDMOS supply voltage of 50 volts, approximately 10 to 14 
amps is required to get the 350 watt output with a control of 8 watts, a 
comfortable 16 dB gain.

Italian Technology Broadcast offers 490 Euro ex VAT a module for sale 
consisting of a built pallet with all parts on it and a copper base of 
9.5 mm thick that needs to be mounted on a cooling plate.

Further information and how to order this unit can be found via:

For those for whom this power is not yet sufficient, NXP has also 
announced a bigger brother, the MRF13750H, which can deliver an output 
of no less than 750 Watts in the band from 700 MHz up to and including 
1300 MHz. With almost 20 dB gain, approximately 10 Watts is sufficient 
to send the transistor. This transistor will probably soon be on the 
market and possibly also as a complete one
power pallets become available. Data from this transistor can be found at:

70 cm EME with only 10 watts
On 2 December 2017, the M6EBQ succeeded in making a 70cm EME QSO with 
DL7APV with only 10 Watt output. The connection in WSJT was made with 10 
W output from a Yeasu FT857 and as antenna a DG7YBN 70-17m 17 element Yagi.

The antenna used to design by DG7YBN uses a flat folded dipole with 
which very favorable characteristics can be achieved.

The antenna has the property that the side lobes at the back are very 
well suppressed and thus a very good front-rear ratio for the length of 
this antenna.

With 3.63 meters in length and a gain of 17.3 dBi and a front-back ratio 
of no less than 38 dB, this is also a very suitable antenna for 
contests. Of course, therefore, there is also little noise picked up and 
the antenna is also very suitable for moonbounce.

Information on how to make this antenna can be found at:

On 01/26/2018 01:43 PM, Brad Brooks wrote:
> For those who receive the DKARS magazine, there is a very interesting article. The transceiver described is for ATV, but it looks like like it will tune to the AO-92 uplink frequency. Seems to put out 400mw FM out. I am not able to take time now to review deeper (stealing away from work) but I look forward to parsing through the schematic/links this weekend. I am forwarding this notice for anyone who will be able to get there sooner. I think there is some potential here, and I would like to know other’ opinions.
> Www.dkars.nl
> 73 Brad WF7T
> Nashville TN EM66
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