50mhz activity

The place to discuss reduced bandwidth fast scan amateur television on 70cms and below
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G4HTZ
Posts: 172
Joined: Sat Aug 02, 2014 4:21 pm

50mhz activity

Post by G4HTZ » Sun Jan 13, 2019 10:33 am

Just been reading about G4FRE 50mhz tests ....having returned a few months ago from our middle age gap year to Spain ..I am gradually putting the station back together ...having recently acquired a tilt over 15m mast makes antenna work a lot easier.

Anyway I remembered I had a RN electronics 144 to 50mhz transverter ...guessing this would be suitable for using with my portsdown and minitoune RX ...must box them up one day !!! ....I also have a Gemini dual band 50/70 mhz linear amp which puts out about 300w ...so guess it might be ok for about 100w narrowband datv ??? .... antennas available dual band 6/4m moxon or 3+3 dualband innovantennas yagi ...both about 6dbi gain

So guess the above should work well on 51 mhz ????

Qth here is only 3m asl on east Essex coast ...500m to North Sea ....great sea path to continent..not so good for uk ..but who knows !!!

If anyone interested in any 50mhz tests sometime I will try and get it hooked up ...if not will leave it all in the loft !!!

Steve G4HTZ JO01JN
Steve G4HTZ
Great Wakering Essex JO01JN

g8vpg
Posts: 309
Joined: Fri Oct 11, 2013 9:35 am

Re: 50mhz activity

Post by g8vpg » Sun Jan 13, 2019 12:45 pm

Steve,
My experience has been that amateur "linear" amplifiers sold for ssb/cw use are not good enough for digital ATV use. We really need class A linears, which you can tell because they draw a heavy bias current with no drive.
73 Shaun.

g0mjw
Posts: 868
Joined: Sat Sep 20, 2014 9:15 am

Re: 50mhz activity

Post by g0mjw » Sun Jan 13, 2019 12:52 pm

LDMOS devices as used in the Gemini can produce reasonable power, say 30W if you turn up the bias. As long as the cooling can cope.

Mike

G4HTZ
Posts: 172
Joined: Sat Aug 02, 2014 4:21 pm

Re: 50mhz activity

Post by G4HTZ » Sun Jan 13, 2019 1:38 pm

Hi Shaun and mike
Ok thanks for information...that's a pity re the Gemini amp .
Thanks
Steve
Steve G4HTZ
Great Wakering Essex JO01JN

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