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Thanks Raj, very much appreciated! I will have to do this mod then which does not jeopardise the output power!

I only just noticed it after I posted my reply to Iz, but your mod is now up on the website! A very simple fix, albeit requiring the ordering of surface mount parts ...? The question is why does it

Mike, see my SIMPLER spur fix without loss of Po! Tested on two boards here.. Raj

Iz Spurs news item: http://ubitx.net/2018/09/15/details-of-the-anti-spurs-mod-added-45mhz-filter/ Just 3 parts and you will have that one licked.?? However, it may just be an expensive way of

I found good reduction of spurs with the following mods: 1. Replace L5 with an SMD inductor 680nH or 681, mount at right angles to old toroid 2. Replace L7 as above. The 45MHz filter is not required

Mike, what are the three parts to resolve spurs? I might have missed something.

Eliott The latest version of the uBITx is the v4, which doesn't have an audio chip at all (it has discrete transistors). The v4 board MAY have audio issues ... a small proportion of owners have

this is a very well designed amp. the extensive use of feedback helps preserve linearity. we don't get the BS170 transistors in india for some strange reason. i might as well just order this to play

The contacts are below, close to the ground plane possible less coupling and short so less inductance. Raj Pic: from the net. Emacs!

OK 13db gain for the final stage. As many of us have 0.7-1w qrps what is the (approximate) absolute maximum rating for the input power of the final stage without going nonlinear? 0.5w or more?

Should be easy enough to replace Q13 with a through-hole 2n3904. And should work fine. You need to first remove the old surface mount MMBT3904 at Q13. Heat up the pin that's alone along one side with

Nice analysis. Could you please try with smd inductor 100uH, Please !! regards vu3zmv

Hello. It looks like I've damaged Q13 on my Bitx40 v3 board, this is annoying because the diodes for the protection modification are sitting on my bench not installed.? I happen to have some 2N3904

Sure is fun with good test equipment........ I deleted the last picture because it may cause confusion. #1 The first plot is the coupling between the Armature and the coil for a small 10 pin Omron

Just one more comment to Hans. I have order a kit, going to build a monobander 10/11m SSB rig. But, I am just reading through the PA's manual, and really, your manuals are second to none!? Absolutely

Hi All. Just remembered, the GQRP SPRAT magazine recently had an article for a +-30db amp based on the MMBTH10 if I remember correctly. It used 4 of them. Ill see if i can find more details to share I

Well you know how these things are, every time you vary one thing, something else changes... so it's hard to be totally precise. But approximately the gain is split equally between the two stages.

Jerry, I agree that we need more than one MMIC for the TX gain stages. My initial idea was/is? to replace the "famous" Q90 with a three transistor W7ZOI amp (gain = 15 dB) may be using even BFR106

You could update the firmware, 1.1 is out. A few things. Are you using a Nextion, have you built the extra stuff necessary (ie, another arduino nano?). (I have a question about that, there's got to be

Kees Has anyone tried adding a 0.1 mfd across each of the relay coils, and additional 0.1 mfd to ground from various places in the DC going to these relays. Suspicion is that some of the unwanted