PAs for Portsdown

Discussion about this major DATV Project. See also https://wiki.batc.tv/The_Portsdown_Transmitter
radiogareth
Posts: 15
Joined: Wed Jan 06, 2016 9:46 am

Re: PAs for Portsdown

Postby radiogareth » Sun Nov 19, 2017 7:54 pm

Wondering what people are using as PA's on 70MHz (low band Pye sets at much reduced power maybe), 144 and 1250?

M0SKM
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Location: Houghton Regis, Beds
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Re: PAs for Portsdown

Postby M0SKM » Sun Nov 19, 2017 8:45 pm

Hi
I'm using the HF amplifier kit from Minikits; works well on 50/70MHz. You'd have to adjust levels for good linearity.

http://www.minikits.com.au/electronic-k ... -Amplifier

Steve

g0mjw
Posts: 330
Joined: Sat Sep 20, 2014 9:15 am

Re: PAs for Portsdown

Postby g0mjw » Sun Nov 19, 2017 9:15 pm

I have a linear broadband amplifier that will do up to a watt and a 500W I0JXX pallet amplifier that when correctly biased can do up to about 25W. I am planning to use just the 1W initially which will be 10W ERP.

Mike

radiogareth
Posts: 15
Joined: Wed Jan 06, 2016 9:46 am

Re: PAs for Portsdown

Postby radiogareth » Mon Nov 20, 2017 5:01 pm

Interesting. These http://www.ebay.co.uk/itm/170W-FM-VHF-8 ... SwQaJXSBqU go like a rocket and other than needing 28 volts for max beans may be useful. As a guide, It will deliver 110W out on 4M with 2.5 watt drive. So throttled right back we might see 20 watts?? I'm NOT an RF expert in any shape or form, but a happy experimenter.....
It also does 6M and 2 M although the input matching may need tweaking.

G4uvz
Posts: 9
Joined: Sat Dec 09, 2017 10:30 am

Re: PAs for Portsdown

Postby G4uvz » Sun Dec 10, 2017 8:50 pm

OK I have 10mW coming out of my Portsdown ! I understand that most use a Mitsubishi module for 2 and 70cms I have a wideband ' linear; amp which is delivering around 200mW
So my question which ones do I need and where do you get them?
Adrian

g0mjw
Posts: 330
Joined: Sat Sep 20, 2014 9:15 am

Re: PAs for Portsdown

Postby g0mjw » Sun Dec 10, 2017 8:58 pm

Minikits are a good suppler http://www.minikits.com.au/ specifically http://www.minikits.com.au/electronic-k ... high-power

RA60H3847M1 RF Module 60W 378-470MHz for 70cm
RA18H1213G RF Module 18W 1240-1300MHz for 23cm

For 2m have a look at M0DTS web page. http://www.m0dts.co.uk/index.php?tag=146MHz

Roberto Zech DG0VE https://www.dg0ve.de/en/ or Bert Modermann PE1RKI http://www.pe1rki.com/ for ready made units.

Mike

G4uvz
Posts: 9
Joined: Sat Dec 09, 2017 10:30 am

Re: PAs for Portsdown

Postby G4uvz » Sun Dec 10, 2017 10:28 pm

Thanks for the info ..but not sure that it is what I want! Really want to homebrew and I thought that I could get a 60-80 watt module and under run ? The minikkits only seem to do an 8 watt 2 M unit?
I was totally confused with the M0DTS site!

M0SKM
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Location: Houghton Regis, Beds
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Re: PAs for Portsdown

Postby M0SKM » Sun Dec 10, 2017 11:09 pm

Try this link for the high power RF amplifiers. Select the appropriate board for the band; and the choice of Mitsubishi modules to match will be revealed.

http://www.minikits.com.au/electronic-k ... high-power

Also this link on the M0DTS site for a 2 metre PA.

http://www.m0dts.co.uk/index.php?item=144

Steve

g8gtz
Posts: 764
Joined: Wed Apr 07, 2010 6:26 pm

Re: PAs for Portsdown

Postby g8gtz » Mon Dec 11, 2017 9:05 am

https://wiki.batc.tv/146_MHz_amplifiers

Has more detail on the M0DTS PA (CQ-TV 247 and 249) and also the Mitsubishi brick amplifier which several people use (including myself) - module from Anglia components and PCB from Sam G4DDK.

73 Noel

G4FRE
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Joined: Fri May 26, 2017 6:57 am
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Re: PAs for Portsdown

Postby G4FRE » Mon Dec 11, 2017 12:47 pm

The last link is broken (error 404) , the gm3sek 60w circuit is at

http://www.ifwtech.co.uk/g3sek/vhfdx/gm ... -board.jpg (.jpg missing from the end of link)

Dave
g4fre


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