Posts by DJ0MY

    Leo Bodnar GPSDO is not Sine Wave output - see data on their website...

    Both output signals square wave at 3.3V CMOS levels with 50 Ohms characteristic impedance. Their output drive levels can be adjusted and outputs can be enabled and disabled independently.

    Output power level (measured at 10MHz, fundamental power channel):

    +13.3dBm, drive setting 32mA

    +12.7dBm, drive setting 24mA

    +11.4dBm, drive setting 16mA

    +7.7dBm, drive setting 8mA

    Its mentioned here:…duct_info&products_id=234

    So all is 100% OK, hi hi...

    73, Oscar


    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

    Maybe your diameter is too large resulting in too low resonance? Or the plastic tubing has an effect on reducing the resonance frequency as compare to air wound helixes?

    73, Oscar

    Thanks Sandor. Highly appreciated! (WhatsApp was not showing any User name on my phone, so I was not aware it was you)...

    In parallel I've also got those 2x22 ohms measured by Arved M0KDS....(for the -160 version) to whom I also send my thanks...

    73 and thanks for all the help

    My Amplifier is repaired in the meantime. It was the faulty resistors that are feeding into the bias circuit with 28V...

    Mine were 3.7kohm and replaced all by 11 ohms and works perfectly.

    In the -160 version they use two in parallel (instead of only one in the -150 LDMOS version).

    Maybe a good mod for -150 type users to solder in two 22 ohms in parallel.

    Maybe more durable, hi hi...

    73, Oscar

    Thanks Heiner, but not really, since this is a totally different PA (this is the "small" Polish PA) but Bias circuit seems to have some similarities....also this one is a single package (more similar to the -160 devices) and not a dual package (like the -150 devices)...

    Will continue searching.

    73, de Oscar

    Hello friends,

    so far no sucess in spotting faulty C's or R's (3.7kOhm and 37kOhm feeding the two BLD6G22L-150BN/2 bias regulator ICs and also 3.7kOhm feeding the 2nd stage regulator). Those values are much different than the 150ohms that Dave G3XOU reported here (Post #190). I am not sure what the nominal values should actually be.

    C's at least do not seem to be short circuited, but since its not recommended to power it up with an open lid I am not sure how to do further measurements in e.g. powered state or using thermal spray as someone sugessted here in an old post?

    Did someone successfully added external biasing to the PA variant with BLD6G22L-150BN/2?

    The BLF8G22LS-160BV version uses only one single bias feeding line per device, which makes it easy.

    The -150 version however since it is a double package would require feeding at four points of the final stages.

    The "inner" two points on the PCB seem to be fed from an inner PCB layer coming from the bias circuit.

    Did someone already try to locate some convenient common point per device in the area of the biasing circuit where to interrupt original and connect external biasing for the -150 device PCB layout and is willing to share insights?

    The -160 seems to be soo much easier to feed with external Bias in this respect without having to think much about routing of the wires ec., hi...

    73, Oscar

    I did the snowflaking tonight to my Nokia-Siemens PA and after I mounted everything very nicely together, the lid was closed and I fired everything up with a very gentle drive of my Pluto + CN047 I was wondering about too low output as compared to the unmodified tests made before.

    Driving the drive up very much I got something like 10-15W out at best.

    Much less than in the previous unmodified state.

    I then measured the IDq of the 28V supply and instead of seeing the usual nominal 1.9A that I saw before now there is only around 250mA oscilating sometimes up to 350mA (at least its moving slowly up/down and is not absolutely steady)

    Looks like I have a faulty bias regulation like many other have reported here? I wonder why this happened so suddenly.

    (but seems also a similar "sudden death" as the others here who experienced the same)

    I need to see if I can locate the faulty R and/or C and temporarily fix it....(any hints on how to locate them?)

    Or discard it and just use external biasing...which is perhaps the best solution.


    You should measure it under load at the Pluto...I recall my readings to be much lower, but have no access to a suitable scope right now...maybe someone here could measure some proper measurements at the Pluto TRX chip input.


    I have it also directly connected to one of my Pluto's and no problems at all since a few months.

    I remember that I did some measurements right after the modification with a RF Probe and Oscilloscope and the amplitude at the lowest output setting was not really reaching critical levels (but I forgot how much it was exactly - maybe someone else could measure and post here?)

    73, Oscar

    First I draw the theoretical footprint of the sat based on the position and distance from the earth. Then I generated the DXCC list.

    See files attached.

    Nice DXCC List. Seems that OX (North America) is issing in the list, which has a low elevation access to QO-100 from some of the villages on the East Coast. Otherwise a nice complete list.

    73, Oscar

    Just as a reference - I was using RS15 (and its ancessors) during the "good old times" - in the old days just 25W on a 1/4 groundplane was more than sufficient to work the RS birds on the uplink.

    But this might be different now of course.

    Keep us informed about the progress.

    73, Oscar

    Yesterday I fired up mine (BLD6G22L-150BN2 variant) for the first time without smoke, hi hi.

    I just tried it first in unmodified way. (only replaced the Input and output connectors, nothing else so far)

    All Bias currents looked just fine as described here and (so far) no problems with unstable internal bias circuits.

    But this could still happen, like others have experienced...

    The amp produced nice strong signals, hi hi (I drove it up to approx. 8A at 28V, but cannot check output power right now).

    However I noticed that audio was not sounding very clean as with my other amps (SG Labs or PA3AXA), a bit rough, specially when underdriving the amp for lower power output. Could this be related to the Doherty mode or to the Bias being optimised for contiunous data modes?

    Regarding snowflaking I need to upgrade my measurement devices first, so I am not really ready for that yet (or at least have it calibrated against a good reference).

    I wonder if the modification of the Doherty circuit is worth it? And perhaps also externally biasing it?

    DB8TF In an older post you decribed your biasing circuit, but would be great if you could draw it on a piece of paper and post it here for more clarity?

    Someone also mentioned (I think it was Sandor DM4DS on some other channel) that the 1st stage amp presents a total system limitation on 2.4GHz and is partially responsible for the -10dB amplification many people see on 2.4 vs. the original design frequency.

    Can someone confirm this is the case?

    So one of my next first things would be to remove it and do a direct connection to the second stage (similar as in YO5ER photo and others). It seems to me there are still some hams playing with this amp type so all hints published here could help others. Thanks for all the great posts so far.

    73, Oscar

    Based on the pictures I would agree that the skew angle is not set correctly, but above all I would not really trust that adjustable LNB arm either. It seems that not only the angle is variable but also the height? (since it uses a longitudinal hole) ?

    Definitievely worth tweaking after you made sure that the azimuth is 100% corrently set to maximum signal.

    When using the SDR in wideband mode (e.g. displaying around 1 - 1.5 MHz bandwith of spectrum) you should clearly see with your dish size at least 1-3dB noise level incease in the middle of the passband as compared to the noise levels seen on the spectrum display outside of the passband)

    73, Oscar

    I am just in preparation of firing up and modifying my Nokia UMTS PA (the one with 2x BLF8G22LS-150) that I've got last year from the source in Poland mentioned here.

    In order to get a decent PWR cable connection I just made small PCB adaptors for the 2x5 pin heders (2mm types)...

    Since the price was identical for 4 pieces or 20 pieces I ordered 20 pieces - so I have many spare ones now :-)

    If someone is interested in a pair of these PCBs for their amp let me know by direct message.

    73, Oscar