Re: 144MHz Gain block

Andy G4JNT

Transerter interfacing is a bit of a pain

Of course, starting from scratch the 1mW output from the Elad on its LP port is perfect for driving Tx mixers directly.   The RF is generated at a sampling rate of 368MHz, so only a bit of alias filtering is needed - a three section elliptic with the zero at 223MHz is more than adequate.   (On Rx it needs 30dB or more of gain and bandpass filtering to get rid of other alias responses).

But with all my transverters designed for FT817 compatibility, that's the way they're staying

On Thu, 22 Nov 2018 at 17:17, SAM JEWELL via Groups.Io <> wrote:
That’s what I thought. I was disappointed (perhaps not surprised though) that i could not get 2W out at any frequency,  but the gain was a surprise. As used on the output of one of my transverters, I decided to ditch the first stage and just run the second stage. I am not sure what the device is. Possibly RFMOS fet. It does need forward bias, whereas the first stage is just a high gain MMIC? The second stage bias is on the  board. The whole thing runs happily on 12V. It brings the Iceni or Anglian transverter output up enough to drive one of the SGLabs 23 or 13cm transverters if you don’t want to modify one of those for the lower input. 
Sam,   G4DDK

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On Thursday, November 22, 2018, 5:09 pm, Andy G4JNT <andy.g4jnt@...> wrote:

Danke ...

I've ordered one.   1MHz to 1GHz , 2 Watt saturated.

Hopefully the raw device will be identifiable, but as usual with these Chinese modules, probably cheaper buying ready built like this than it is to get the components.

On Thu, 22 Nov 2018 at 17:00, SAM JEWELL via Groups.Io <> wrote:
Yes, Andy the little ‘2 Watt’ 2 stage wideband amplifiers on EBay will do 1W at very good linearity. Really awful much above that and excellent at 500mW. They will do HF through 500MHz. Performance is much worse above that. If you need low gain then ditch the first stage. Over 50dB gain at low HF!
They have a small, but adequate heatsink on the rear of the board.
I don’t have an Ebay reference, but you can’t fail to see them once you start looking.......

Sam, G4DDK

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On Thursday, November 22, 2018, 4:26 pm, Andy G4JNT <andy.g4jnt@...> wrote:

I need a gain block to go from a little under 0dBm up to a bit over 27dBm or 500mW.   This is needed to make my Elad FDM-DUO "look like" the FT817 for driving transverters.
But it's a very inconvenient gain arrangement to get using gain blocks
PGA-103 etc go to 50mW and needs the input attenuating.  Then any discrete device after that has to be wound back so much it gets silly. 
Meaning :   Atten - Gain - Atten Gain

Is there an off the shelf solution to 27dB - 30dB gain  up to 1 Watt output?  Or will it have to be a pair of bipolars with old-fashioned discrete circuitry

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