6m & 4m LDMOS Dual band PA

 

I have been fortunate enough to get a really nice reference design pallet LDMOS-PA. As it stands it works from about 47-76 MHz so it was fairly obvious that I had a contender for a dual band amplifier. The device is not yet readily available so I can’t say exactly what it is yet but as soon as it is released I will say and share the test data

I can say that at P1dB with 50V the amplifier will produce 1100W, however for acceptable intermodulation performance 950W is more appropriate. Of course G4NOK does not have an SRP for 6m or 4m and so the legal limits will for both bands will be strictly adhered to.

The amplifier is for a radio club and as such may occasionally be used by inexperienced operators. Therefore it is imperative that control to prevent overdrive, bad SWR, over current and also excessive output power has to be accommodated.

The F1TE control boards fit the bill perfectly in conjunction with a very flat high power directional coupler.

Here is a taster of a few of the bits – I will start the case metalwork next week. More details will be added as I go along.

Of course we will be needing a low pass filter, these are very over engineered but this amplifier needs to be bomb proof. They were made for me by Marco Schippel of FMBroadcastParts.

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6m & 4m Low Pass Filters – the harmonics are dumped into the dummy load and not reflected into the PA device.

High power directional coupler for output monitoring, forward and reflected power (hence SWR) - designed and made by Bert Modderman PE1RKI

High power directional coupler for output monitoring, forward and reflected power (hence SWR) – designed and made by Bert Modderman PE1RKI

More to follow.

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