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habamp use as amp for a DTX1 ??
Posted: Fri Oct 10, 2014 2:52 pm
by G4HTZ
just getting the bits together for 70cms DATV
bought a DG0VE converter and have a tetra amp on its way
on the TX side am considering the DTX1
I have a HABAMP which i was going to use as a preamp before I bought the DG0VE converter
would the HABAMP be suitable to use as a amplifier for the DTX1...it produces about 27dbm at 70cms followed by a filter...if so I could use this as a low level drive for the tetra amp
Re: habamp use as amp for a DTX1 ??
Posted: Sat Oct 11, 2014 7:13 pm
by M0DTS
Hi Steve,
The HABAMP will give about 30mW from DTX1 if the gain figures are correct.
But the problem looks like the filter, it rolls off by about 5dB from 437-438MHz where we normally operate.
Rob
Re: habamp use as amp for a DTX1 ??
Posted: Sat Oct 11, 2014 8:11 pm
by G4HTZ
Ok rob
Thanks for info
Steve
Re: habamp use as amp for a DTX1 ??
Posted: Sun Oct 12, 2014 10:33 am
by 2E0DTX
Hi -
Why not take a look at the filter here
http://www.dtx1.info/NewProducts.html
The DTXF-70 would be the one to look at.
73's
Laurence 2E0DTX
Re: habamp use as amp for a DTX1 ??
Posted: Sun Oct 12, 2014 6:02 pm
by G4HTZ
Need to get power up from the -5dbm to a few watts ...will need a amp of some kind to take the low level
Re: habamp use as amp for a DTX1 ??
Posted: Mon Oct 13, 2014 7:35 am
by g4wvu
IIRC the Nokia Tetra amplifier lumps can be driven from as low as -15dBm if you include all the drive stages - don't have details to hand but will look out shortly.
Re: habamp use as amp for a DTX1 ??
Posted: Mon Oct 13, 2014 9:09 am
by g4wvu
On Robs site some details specifically low level drive
http://www.m0dts.co.uk/?tag=432MHz&item=68
Re: habamp use as amp for a DTX1 ??
Posted: Mon Oct 13, 2014 1:42 pm
by G4HTZ
Yes will have to investigate that mod further
Cheers
Steve
Re: habamp use as amp for a DTX1 ??
Posted: Tue Oct 14, 2014 7:32 am
by g4wvu
Good luck - I will be doing similar when I get around to modifying the Nokia lump I have here. I will look to about 0dBm level as I have a MMIC drive amp in my DTX1 to raise it to a comparable level as an SR Systems TX (max about +6)
I will leave high bias level on the amp as original I think (linearity)
73s
Mark
Re: habamp use as amp for a DTX1 ??
Posted: Tue Oct 14, 2014 4:11 pm
by G4HTZ
Ok mark
May be possible to work you on 70cms atv some time
Often get gb3lo and TN down here on 24cms with a slight lift
Good luck with tha amp ...still waiting for mine to arrive
Regards
Steve