New QRO mobile HF/VHF Linear Amplifier

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Unit 148 Mobile
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New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 09 Aug 2018, 07:05

I hope this project of mine will be of interest to the mad few.

A few CAD images to wet your appetite.

Basic spec planned;

1500W pep output with very low IMD.

Dual 50V LDMOS in the output.

In-board DC top DC converter allowing direct connection to vehicle's stock battery system although this may need beefing up.

160 - 6m coverage.

Built-in active attenuator so will be suited to any transceiver with 10W to 150W RF output.

I'm considering a remote under-dash mounted head unit with 7" touch-screen display. Prototype chassis size 30 x 10 x 50CM.

Enjoy.

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 09 Aug 2018, 07:06

PAmp-rear-v2.jpg
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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 09 Aug 2018, 07:10

Internal rear of chassis.
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Re: New QRO mobile HF/VHF Linear Amplifier

Post by radiogaga » 09 Aug 2018, 08:07

I'm no expert but it does look pretty. Do those sizes allow a heatsink? My only experience is the internet trawls in the past.

I have this saved:https://www.w6pql.com/parts_i_can_provide.htm#hfthings

and the sink for that would be too tight on your case.

I'm sure you have have it all covered.

Good luck!
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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 09 Aug 2018, 13:08

Hi RG,
Internal heatsink within a sub-chassis chimney design. The Meccal (Italy) heatsink is from memory 300mm wide, 450mm deep and 80mm high with a 15mm flange. I will mill this so there will be a flush mounted copper heat spreader within the dimensions of the heatsink rather than sitting on top like most commercial amplifiers.
I think I posted incorrect dimensions of the chassis in my first post in as much as the width will be 35cm and not 30.

The heatsink is mounted hard up against the chassis front panel and the vertical slots accurately match those of the heatsink profile. The internally mounted fans suck air in from the front with the exhaust out the rear. This is way more efficient than the typical CB and some amateur commercial fan hood's.
Further down the road I may be able to reduce the dimensions of this chassis but I need a large enough area right now to mount all the pcb's to reach a proof of concept and do some testing.

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 09 Aug 2018, 13:12

Please recheck my original dimensions. They are in CM which are correct! 😊

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 09 Aug 2018, 13:13

Plenty of room for a very large heatsink.

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by radiogaga » 09 Aug 2018, 13:13

... Sorry got my inches and cm confused.... No comments !

Still looks very pretty. Are you following any of the plans/kits on the W6PQL? It appears you are looking to achieve the same thing?

Keep the posts coming.

:thumbup:
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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 09 Aug 2018, 16:07

Well, the PQL amplifier is a base station amplifier whiler this project as the title states is for a mobile amplifier.

I will not be using PQL's design. I plan on basing my amplifier around the RF2K, a German designed kit: http://rf-kit.de/en/ however I will not be stacking PCB's on top of one another preferring a more aesthetic layout like my current Metron. Image enclosed of this 30 years old amp.

The largest surface area will be taken up by the DC to DC converter which puts out 48V at 50A,

RF2K PA module & Metron images also enclosed.

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 10 Aug 2018, 12:04

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 26 Sep 2018, 19:22

Some initial renders of the planned case.

I took the name and changed the model number to reflect the higher output of the original Metron mobile amplifier from the 1980's used in my avatar

Some changes to do to the OLED which I took from a FM transmitter but you get the idea.

You can double click on the images for super high res.

What do you all think?

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Blackolive » 27 Sep 2018, 13:23

Very neat. Just a thought as its being designed for mobile use. is there any metal at the sides under the outer panels for the inclusion of threaded holes for a mobile mounting bracket

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 27 Sep 2018, 15:36

Good observation.

There will be however due to size and weight I think the only place where this would be located is in the boot (trunk). I will insert hank-bushes and a mounting tray will sit underneath the amplifier.
Testing a 1kW PA module over the next few days but at present I think we're still short of amperage at 14V for this let alone a dual LDMOS version for the full 1500W.

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by theEarwigger » 30 Sep 2018, 13:45

Very Nice.

I wish my car was big enough to have a battery capable of powering it... curse that 400W UK ham radio power limit!

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Re: New QRO mobile HF/VHF Linear Amplifier

Post by Unit 148 Mobile » 02 Oct 2018, 17:41

Hi Rob,

How are things with you?

I've not mailed you for any updates for a while!

The alternator produces the current the battery just takes the shock :-)

David
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