What TX amplifier do you plan to use?

ik1hgi Tony · May 26th 2020

Quote from PE1GLX

Ciao a tutti,

Questo fine settimana ho avuto i miei 2x amplificatori Nokia BLD6G22L 150N / 2 che finalmente trasmettevano con successo DATV a QO100. Dove l'AP assorbe circa 1,75 A senza RF e un po 'sopra i 10A con RF. Dopo 1 ora di gioco ho notato che la potenza andava su e giù (a volte 10A di alimentazione ea volte 5A e anche la corrente di stand-by (no rf) , se menzionati, non funzionavano altri thread ma non riesco a trovare nulla di sbagliato. Qualche suggerimento cosa sta succedendo qui?

Joris

[Attach = '5014', 'none', 'false'] [/ attach]

Display More

Quale amplificatore TX prevedi di utilizzare?

Il mio PA aveva le resistenze, minuscole, che alimentavano il driver e la polarizzazione finale che variavano di valore, quindi la potenza di uscita era fluttuante. Secondo le indicazioni trovate sul forum AMSAT, le ho sostituite. Ora tutto OK Quale amplificatore TX prevedi di utilizzare?

Quale amplificatore TX prevedi di utilizzare? Quale amplificatore TX prevedi di utilizzare?

73 ik1hgi

ik1hgi Tony · May 26th 2020

let's see what happens after making some changes that have recommended me in this forum thanks

73 ik1hgi Tony

PE1GLX · May 26th 2020

Quote from ik1hgi Tony

Quale amplificatore TX prevedi di utilizzare?

Il mio PA aveva le resistenze, minuscole, che alimentavano il driver e la polarizzazione finale che variavano di valore, quindi la potenza di uscita era fluttuante. Secondo le indicazioni trovate sul forum AMSAT, le ho sostituite. Ora tutto OK Quale amplificatore TX prevedi di utilizzare?

Quale amplificatore TX prevedi di utilizzare? Quale amplificatore TX prevedi di utilizzare?

73 ik1hgi

Display More

Hi Tony,

Thanks for the tips, I bridged the resistors that power the bias circuits, The power is stable now, but still too high standby current and too low output power. Next step is to check all bias voltages in the amplifier. (our amplifier have a slightly different layout.)

73 PE1GLX Joris

ik1hgi Tony · May 27th 2020

hello ok well for your stable power, we are two made small changes to this forum, we have unsoldered the small circulator MDX2 difficult, put a trace of 0.1mm wires for the moment I have no suggestions, if we find any happy info to give (pse input we use a small amplifier SPF5189Z power around 80mw)

73 Tony IK1HGI

PE1GLX · May 27th 2020

Quote from ik1hgi Tony

hello ok well for your stable power, we are two made small changes to this forum, we have unsoldered the small circulator MDX2 difficult, put a trace of 0.1mm wires for the moment I have no suggestions, if we find any happy info to give (pse input we use a small amplifier SPF5189Z power around 80mw)

73 Tony IK1HGI

Hi Tony,

If you look at the the picture in #360 you will see that the two first circulators have already been removed. My conclusion at that time was that it did not bring anything so I would not do that again.

but thanks for the tips,

73

Joris PE1GLX

F8CHK · Jun 2nd 2020

Hi all,

Using a Nokia with 2 BLD6G22L 150N/2, after a while I had the same problem as some OM on the list, Bias current disapears...

I am a bit confused with the solution to this problem, some post (#353) refers to a 11 ohms value, and other post (363) to 150 ohms value, or may-be they are not speaking of the same resistors?

Can you help me to be sure?

Tnx and see you on QO-100!

73,

Roland F8CHK

DJ0MY · Jun 2nd 2020

Roland,

they both mean the same resistors. The 150 ohms solution mentioned by some OM was just "what was in the junkbox"....and seem to work.

But actually installed in the factory are 11 ohm (or 2 x 22 ohm in parallel for the larger -160 variant LDMOS).

Did you measure your resistors and checked if they have become faulty (too high resistance)?

73, Oscar

F8CHK · Jun 3rd 2020

Hi Oscar,

Tnx for the reply, this is exactly what I wanted to know! yes my resistors were faulty, and I replace them by 150 Ohms, amp is working again, may be with a slight different bias current.

I think I will go for the 2 x 22 ohms in parallel next time I will open the case!

I am also thinking of using the 28 V bias as a PTT, instead of permanently consumming some 2 amps even in receiving periods, looks like it is possible, what do you think?

73,

Roland F8CHK

PA3GUO · Jun 3rd 2020

few questions

1. Faulty resistors: what was faulty: their soldering, overheated, change in resistance/open/short?

2. Does anyone have a datasheet of the BLD6G22L 150N/2?

Henk

DB8TF · Jun 3rd 2020

PA3GUO: i am searching for the datasheet about one year now without luck.

It seems that this BLD was a special build for the customer.

Around here in this Thread: What TX amplifier do you plan to use?

73s

F8CHK · Jun 3rd 2020

Faulty resistors: in my case it was a change in value, they got a high value, so no bias at all. Why that change? this is the question ! and it appears to arrive frequently...

Hope it will be good for a while now!

73,

Roland F8CHK.

DD1US · Jun 3rd 2020

Hi,

I suspect that the problem occurs when the supply voltage gets switched on with a high slew rate.

Maybe the original power supply has a well defined slope of the supply voltage ramping up.

I had several problems when I started to switch on the supply voltage using a relay in the drain supply.

Before I had tested and several of those amplifiers with a lab power supply and never had a problem.

I am just guessing but maybe my observations can help to trace down the root cause.

Kind regards

Matthias

http://www.dd1us.de

PA3GUO · Jun 3rd 2020

thanks for yr responses. I am working with joris pe1glx to fix his PA.

Henk

F8CHK · Jun 3rd 2020

DD1US , I think I agree with you, because in my case, the problem had appeared when I changed the way the 28 V was apply to the amp. At the beggining I switched the power supply, all was fine. In a second time, I switch the 28 V of the amp via a manual switch, with power supply ON, and the fault appears...

So may-be we need to slowly supply the amp...

73,

Roland F8CHK

DH2VA · Jun 3rd 2020

Has anybody thought about controlling the gate bias voltage startup? First apply drain, then with some delay gate? You could actually use this method as PTT.. This obviously works only for LDMOS, GaAs FETs are a different beast..

OE3GBB · Jun 14th 2020

Hello All,

I have two of these Andrew pallets, which I want to use in push-pull with 90° phasing. These amplifiers are each with two MRF7S21170HS transistors and Xinger XC2110E-03S. I have found some reports from Andrew pallets with other transistors, but not with these ones. From the Xinger parts data sheet I would assume, that each pallet could deliver 100W DATV on 2,3 GHz, from the transistors I would think of 2x170W-6 dB or about 75W in DATV.
Has anyone used this pallet for DATV on QO-100 yet? I would need some experience reports and results in DATV, and also modifications, if necessary.
Thanks in advance.

Gerhard OE3GBB

dg0opk · Jun 14th 2020