Tetra nokia amps for atv??

[G4HTZ]

Just bought 2 nokia tetra amps for 70cms use ....once modified they will give about 250w out

Has anyone used one for ATV...

Thanks
Steve

[M0DTS]

Hi Steve,

Yes i use one for ATV and SSB here.
Be careful not to run them at high output continuously when testing as the output coupler will burn out very quickly at 150w+, Fine at high power for cw/ssb duty cycle.

I managed ~200w out of mine but it gets a bit compressed there, you will get about 60w of clean Digital ATV on 70cm with it.

Rob
M0DTS

[G4KLB]

Yes, several people are using them for DATV, they work very well.
I would not do the bias mods, best left in class A, in my opinion.
Spectral regrowth appears at around 80W, I have run one at 100W.
I haven’t done the mods to replace the sage line, so couldn’t run higher power anyway.
One of mine drops 20W with the lid on! So still some work to do this end.
You did well to find them, seem to be a fortune on ebay now!

Have a look at Rob M0DTS mods http://www.m0dts.co.uk/index.php?tag=432MHz&item=68

Colin G4KLB

[G4KLB]

Just beat me to it Rob!

[G4HTZ]

Thanks for the replys

Picked up 2 and a 28v supply for £230 ...one has been modified so will use that for ssb ...and will try the other one for atv unmodified as suggested

Yes seen some on eBay for £275

Cheers
Steve

[G4HTZ]

I see from robs website that they can except a low level drive ...so am I correct in assuming something like DTX1 could be used at this low level drive input

[G4KLB]

Yes that should work, I run a SR systems which is low level and have to fit 18dB of attenuation!
You will have to check what the DTX1 gives out, but I suspect it will almost be exactly what you need.

Colin G4KLB

[M0DTS]

Yes the DTX-1 will be somewhere near, make sure you have a good filter after the DTX-1 as at this low input everything gets amplified a lot!

The nokia amps were going for £30-50 at one time but the source has dried up now i think...

Rob