For those of you that are interested in antennas here is a picture of my
new 6 element beam for 70 MHz. There is just about enough clearance
to fit it on my mast.
I am currently looking at a Freescale MRFE6VP6300H 300 watt LDMOS
device as a replacement for the venerable MRF151G in one of my amplifiers.
The device is in the same package, runs off the same voltage, and the Freescale
Appnote uses a very similar matching circuit to the AR305 based circuit I
currently have. It will be interesting to see how well it works. The Freescale
device has a much higher gain and it considerably more rugged than the
MRF151G also Digikey sell them for less than the 151 can be bought on eBay.
By now those of you that follow my Amateur Radio meanderings
have probably realised the glacial pace that I operate/deveolp at.
After an out of the blue email from New Zealand about something
I posted in 2008 I have decided to get my 70 MHz setup sorted.
I built the 10 - 175MHz amplifier design from
Communications Concepts a few years ago but apart from proving
I could get 300 watts out of it I have never used it in anger.
Well that is all about to change! I have modified the old G3WPO
transverter I use on 4m to work with the amplifier. To drive the
transverter I have decided to use a FlexRadio FLEX-1500.
After my experience with the broken antennas a couple of weeks ago
I have decided to buy an antenna rather than make one, that way
if the worse happens I won't feel so bad about all the wasted time.
Currently I am considering an antenna from InnoVAntennas I have
heard good things about their range of antennas.
Keeping the theme of my laid back approach to radio I quite like
4m contests. There is plenty of time to chat with people (as there are so
few of them), propagation is better than 2m and occasionally you get
sporadic E openings. I just hope in the 2 years I have been away from
4m contesting it has not turned into another band full of pratts!
About 10 years ago I wrote an application that implemented
the serial tone modem which forms part of MIL-STD 188-110A.
It worked but the performance was never great and I couldn't be
bother to tweak it.
Well I am glad to say Steve N2CKH has taken up the challenge and after
many hundreds of hours with the program and a Rockwell HF
channel simulator he has managed to get the program to perform
within a whisker of hardware modems from the likes of
Rockwell, Harris etc. Well done Steve.
His application is for use in US MARS and the modem seems to be
proving its worth during exercises. I watch with interest as to
how things develop.
Oh dear how silly I feel. A few days ago I was lowering
my Tennamast to add an HF dipole to the top and I forgot
to engage the locking bolt. Consequently the Tennamast tilted
over in an uncontrolled manner and completely trashed my
24cms and 70cms ATV antennas. They are just a mangle of
Aluminium now. I won't make that mistake again!
I was planning to replace the 24cms antenna but I am a bit
gutted about the homebrew 70cms antenna because I spent
an awful lot of time making it.
Currently I have a HF Cobwebb antenna up on the mast and
no ATV antennas. I shall return!
