Amplifiers

[G7JTT]

Hi all after putting the Portsdown together what are people doing to get from the flea power to usable output ? I've used Robs M0DTS design for 2m using the RD06/RD15 and on 23cm I have a surplus 1800mhz PA that gives me around 10W, but what are others using ? has anyone come up with something cheap and easy for 70cm ? I see that the RD15 can be used upto around 500mhz at reduce gain has anyone tried it at 70cm ? I did buy one of the broadband 2w pa's off ebay but that proved to be a waste of time in its original state, although I haven't given up yet I've bypassed the first stage and reduced the bias on the final stage to 4.5v and it seems a lot better with well reduced output (need to get it checked on a analyser next).

Cheers John

[G4KLB]

70cm only needs a brick amplifier and filter.
You will need to attenuate the input from the Portsdown or it will give 50W out

70cm PAs.jpg (474.6 KiB) Viewed 5161 times

70cm PA 33.jpg (471.12 KiB) Viewed 5161 times

[G4HTZ]

I ordered a 60w 70cms amp from Roberto DG0VE.....Roberto reckons it will give out about 15w on DATV
http://www.dg0ve.de/en/poweramplifier%200,1-%201ghz.htm

[G7JTT]

Whilst the brick option is going to be an easy route its by no means a cheap one, what I'm after is just a few watts on 70cm so when portable don't have to think about too many amps and battery drain. I have got a 10W brick for 70cm but although that works with my handheld but just wont work with the portsdown. I have found my old MM 70cm ATV and that has a 20W PA which seems able to give a couple of watts from the portsdown but dont really want to remove it from a working bit of kit. There are some very cheap GSM bricks on ebay but I wonder how easy it would be to get them down on 70cm ? Eventually I'll go down the brick route for home, but got to get some antennas up first ! No antenna clause, but seeing as everyone has their sky dishes up no will start putting things up.


John

[G4HTZ]

Whilst the brick option is going to be an easy route its by no means a cheap one, what I'm after is just a few watts on 70cm so when portable don't have to think about too many amps and battery drain. I have got a 10W brick for 70cm but although that works with my handheld but just wont work with the portsdown. I have found my old MM 70cm ATV and that has a 20W PA which seems able to give a couple of watts from the portsdown but dont really want to remove it from a working bit of kit. There are some very cheap GSM bricks on ebay but I wonder how easy it would be to get them down on 70cm ? Eventually I'll go down the brick route for home, but got to get some antennas up first ! No antenna clause, but seeing as everyone has their sky dishes up no will start putting things up.


John

John
I have a ex pmr amp for 70cms which might suit your needs ....if you email me I will send you some pictures of it ....if you want its free essexsteve@icloud.com

[G7JTT]

Just wanted to say thanks to Steve G4HTZ for the donation of the amp and Dave G8GKQ for the help setting up the levels for a clean 4-5W on 437mhz. So I'm now QRV on 4 bands 2m,70cm,23cm & 3cm all QRP at the moment but that suits me. Thanks to everyone involved in the project and all the help received.

John G7JTT