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HF amplifier purchase

Started by Klaus Kragelund March 3, 2020
Hi

I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test 

Tried to find gear that would do that, but they all have 50 ohms output 

Anyone got a link for a amplifier that can do this?

Thanks 

Klaus 
On Tue, 3 Mar 2020 15:42:00 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>Hi > >I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test > >Tried to find gear that would do that, but they all have 50 ohms output > >Anyone got a link for a amplifier that can do this? > >Thanks > >Klaus
How much current do you need? Can you drive both ends opposite phases? Some of the THS-series opamps might do it. Maybe use an eval board. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
onsdag den 4. marts 2020 kl. 00.42.04 UTC+1 skrev Klaus Kragelund:
> Hi > > I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test > > Tried to find gear that would do that, but they all have 50 ohms output > > Anyone got a link for a amplifier that can do this? > > Thanks > > Klaus
think this'll work? https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/eval-ada4870.html#eb-overview
On 2020-03-03 15:42, Klaus Kragelund wrote:
> Hi > > I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test > > Tried to find gear that would do that, but they all have 50 ohms output > > Anyone got a link for a amplifier that can do this? >
That is usually only the rated load impedance, it's not an internal resistance. Even though a professor (!) at my university was teaching that. A modern transistorized ham radio amplifier has a very low output impedance, a few ohms, but it would (hopefully) go into overload protection if you load it with less than 50ohms at full power. Starting at 10kHz would be a challenge, you may have to buy or rent a real EMI susceptibility test amp for that. 40Vpp ain't much though unless this has to drive a near-short at lower frequencies. Ham radio amps start at around 1.5MHz and then go to 30MHz. How much lower they can go depends on the construction. -- Regards, Joerg http://www.analogconsultants.com/
On 2020-03-03 18:42, Klaus Kragelund wrote:
> Hi > > I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test > > Tried to find gear that would do that, but they all have 50 ohms output > > Anyone got a link for a amplifier that can do this? > > Thanks > > Klaus >
Last time I needed something like that I used an 811A. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
On 3/3/2020 5:42 PM, Klaus Kragelund wrote:
> Hi > > I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test > > Tried to find gear that would do that, but they all have 50 ohms output > > Anyone got a link for a amplifier that can do this? > > Thanks > > Klaus >
Have you looked at ENI amplifiers, I think most of them are class A. Probably expensive, here's one, 100watts, 10kHz to 12MHz. 50 ohm output. "The 2100L will work into any load impedance. Into a short circuit or infinite load at some phase angles it may protect itself at power greater than 80% rated power output. Any power reflected due to output load mismatch is absorbed in the amplifier. Therefore, although the output impedance is 50 ohms (maximum VSWR: 2:1), the amplifier will work into any load impedance." "Continuous operation into any load or source impedance"
> https://www.theemcshop.com/dc-220-mhz-rf-amplifiers/1336-used-ei-eni-2100l-rf-power-amplifier-10-khz-12-mhz-100-watts.html
Mikek
On 3/3/2020 7:08 PM, amdx wrote:
> On 3/3/2020 5:42 PM, Klaus Kragelund wrote: >> Hi >> >> I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test >> >> Tried to find gear that would do that, but they all have 50 ohms output >> >> Anyone got a link for a amplifier that can do this? >> >> Thanks >> >> Klaus >> > > &nbsp;Have you looked at ENI amplifiers, I think most of them are class A. > Probably expensive, here's one, 100watts, 10kHz to 12MHz. 50 ohm output. > &nbsp;&nbsp; "The 2100L will work into any load impedance. Into a short circuit > or infinite load at some phase angles it may protect itself at power > greater than 80% rated power output. Any power reflected due to output > load mismatch is absorbed in the amplifier. Therefore, although the > output impedance is 50 ohms (maximum VSWR: 2:1), the amplifier will work > into any load impedance." > "Continuous operation into any load or source impedance" > >> https://www.theemcshop.com/dc-220-mhz-rf-amplifiers/1336-used-ei-eni-2100l-rf-power-amplifier-10-khz-12-mhz-100-watts.html >> > > &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Mikek > > > >
Sorry, they really love these, $9,400!> https://www.ebay.com/itm/ENI-E-I-2100L-RF-Power-Amplifier-10-kHz-12-MHz-100-Watts/303262630551?hash=item469bdc8297:g:NdQAAOSwVRpdYGJY
On Tue, 3 Mar 2020 15:42:00 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>Hi > >I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test
40 Vpp is 14 Vrms
>Tried to find gear that would do that, but they all have 50 ohms output
To drive 14Vrms into 50 ohms requires 4 W power or 0.3 Arms current. A small HF amplifier could easily deliver that, but the problem is the required large frequency range 1:2000, so the question is how well the internal transmission line transformers will handle this frequency range. At least the internal transmission line transformer ferrite material may have to be changed.
>Anyone got a link for a amplifier that can do this?
Some 1:4 or 1:9 external transmission transformers could use to feed also loads of 5.5. 12.5, 200 or 450 ohms.
On Wednesday, March 4, 2020 at 12:57:56 AM UTC+1, John Larkin wrote:
> On Tue, 3 Mar 2020 15:42:00 -0800 (PST), Klaus Kragelund > <klauskvik@hotmail.com> wrote: > > >Hi > > > >I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test > > > >Tried to find gear that would do that, but they all have 50 ohms output > > > >Anyone got a link for a amplifier that can do this? > > > >Thanks > > > >Klaus > > How much current do you need? Can you drive both ends opposite phases? > > Some of the THS-series opamps might do it. Maybe use an eval board. >
I would like to have an instrument, so I do not need to spend time on setup etc. But, I had the same trail of thought, so I ordered this one as a backup solution: https://dk.farnell.com/texas-instruments/ths4031evm/evaluation-module-amplifier/dp/3125639?CMP=i-bf9f-00001000 Cheers Klaus
On Wednesday, March 4, 2020 at 12:59:22 AM UTC+1, Lasse Langwadt Christensen wrote:
> onsdag den 4. marts 2020 kl. 00.42.04 UTC+1 skrev Klaus Kragelund: > > Hi > > > > I need to drive a coil with 40Vpp at 10kHz to 20MHz for a test > > > > Tried to find gear that would do that, but they all have 50 ohms output > > > > Anyone got a link for a amplifier that can do this? > > > > Thanks > > > > Klaus > > think this'll work? https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/eval-ada4870.html#eb-overview
Yes, this could work for sure :-)