Hello all,

Recently I acquired a Nokia ex-UMTS PA, one with two BLD6G22L-150BN dual LDMOSFETs. As with similar PA’s one FET is in class AB and the other is a Doherty in class C. Its bias circuit is in part similar to the circuit DB8SDQ describes in his article about the PA with two BLF8G22LS (which are single FETs). DL8SDQ describes in detail how to disable the Doherty and make that FET linear. In order to find out how to disable the Doherty circuit I explored the bias circuit on my board and discovered a pad next to a ground pad labeled PEAK and AB.

I suspected this could mean exactly what it said, and I tried via a successive series of resistors to ground that pad. With zero resistance to ground the gate voltage rose to 2.1 V, similar to the gate voltage on the linear side. At the same time the current increased from 1.5 to 2.5 amps for the whole PA. So grounding this pad effectively disabled the Doherty and made it work in class AB. As Bert, PA3AOD has a similar PA we had a look at his bias circuit. He has a PA with two BLD6G22L-150BN/2. Its bias circuit is different from mine, but it has also two (unlabeled) pads at the same place in the circuit. He tried shorting these pads with exactly the same effect. So if you have one of these PA’s, shorting these pads should be enough to disable the Doherty. Disabeling the Doherty improved linearity and increased output, especially at lower outputs, as was to be expected.

73 Poll

Hello. I decided install the new transverter 430/2400 MHz. in the room inside the house, because the previous transverter, installed near the antenna, is in qrt definitive due to time. However, the 30 meter long RG 213 used for the connection, generates an attenuation of 13.41 dB at 2,4 GHz. The output power of the transverter is 2 Watts, so the power available at the end of the RG 213 is 91.2 mW. I would install a power amplifier near the antenna with a maximum input of 100 mW and get about 10/20 Watts out in the helix antenna for 2,4 GHz. Thank you for any suggestions.

Quote from IK3XKQ

Hello. I decided install the new transverter 430/2400 MHz. in the room inside the house, because the previous transverter, installed near the antenna, is in qrt definitive due to time. However, the 30 meter long RG 213 used for the connection, generates an attenuation of 13.41 dB at 2,4 GHz. The output power of the transverter is 2 Watts, so the power available at the end of the RG 213 is 91.2 mW. I would install a power amplifier near the antenna with a maximum input of 100 mW and get about 10/20 Watts out in the helix antenna for 2,4 GHz. Thank you for any suggestions.

https://www.sg-lab.com/AMP2400v3/amp2400_v3.html

Quote from HB9SKA

What kind of helix antenna do you have ? A RHCP long one with gain or a LHCP short one as feeder ? With a feeder and dish 10/20 Watts are too strong. Look also here:

Antenna

dish offset 90 cm

Quote from PA3BYV

...

Disabeling the Doherty improved linearity and increased output, especially at lower outputs, as was to be expected.

73 Poll

Poll, I tried it. Сonfirm!

Hello Frank,

you are the first to report that the link was broken.

Here the 2 Files again.

German:

https://magentacloud.de/s/MJe7H4L5wmBmrDn

English:

https://magentacloud.de/s/WYkkACnP4nMn8Ci

Sind das diese Punkte?

vy 73 Gerhard

Danke für die Info. Ich muss ohnehin noch einen weiteren Fehler suchen, denn die PA hat bei einer Fehlersuche kurz geschwungen und dann stimmten die Gate-Spannungen nicht mehr. Eventuell ist einer der Transistoren kaputt.

73 Gerhard

Hello,

just received this new type of pallet from Poland. Is someone allready working on it? I am planning to operate both amplifiers together into a combiner. I allready have good results with a similar 2,6 GHz transistor pallet at 100W DATV. So I expect to get a combined linear power of about 160 W DATV out of this new pallet.
My first analysis is, that there might be a problem with the output isolator. It is designed for 2620 - 2690 MHz. Has anyone measured the actual usable bandwith? The second isolator between driver and PA does have a bypass route, so no problem to cure. The 3dB couplers are from 2,3 to 2,7 GHz.

The question is, if I have to desolder the big isolators to use the coax plugs, or just leave it, or just solder an output line to the combiner just behind the SWR measurement.

73 Gerhard

Hi Gerard, I got this same pallet.

Put it on a big heat sink and gathering info.

I first will check the i2c setting and see if we can controll the 4 bias controllers.

Next I will slowly start to connect the power and see what it will do. Unfortunately I am a bit occupied whit a bunch of other projects so you may beat me setting it on 2400.

Looking forward to compair the notes.

Benno, pa3fbx.

I was under de impression the pallet was made for 2100 MHz and not 2600mhz.

Hi Benno,

great to see that others also are working on this pallet.
For me it is also a side project, at the moment just making a first concept.
No, it is definitly a 2,6 GHz amplifier, from isolator and also transistors. But that is fine as those Doherty amplifiers seem to operate without change on the HF tracks also on 2,4 GHz.

The Polisch vendor sold 7 of those, so maybe someone else will join us.

73 Gerhard

Correct, 27*100 is the maximum operation fequency. So the original use at 2620 - 2690 was correct.
I have seen that it is easier to use those transistors at lower frequnecy than to exceed the maximum frequency.
Therefore I like the 27 types for 13 cm.

73

Hi i double checked but i have a similar but not the same amplifier.

They have the same footprint but BLC922XS-400AVT LD mos..

And i have a BLM7G1822S-40PB driver

So we have complete different amplifies

Ok, yes. This is a 2,1 GHz version. Sorry. Maybe at least the I2C behavior is the same. Please let me know.

73 Gerhard

Have Anyone info and getting started for this PA

73 f4fdw Laurent

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