开云体育

I was interested in Karl K0MWC's suggestion to use a PE digital attenuation chip to address the problem of variable power out on the ?BITx.? (Refer: /g/BITX20/message/42298).?? I was not so thrilled to note that this chip is only available as a "microscopic surface mount" package.

So, I did a bit of searching online and found an alternative device (less precision but we can live with 1dB steps) that is available as a pre-built module (using an HMC470 chip) for around US$13 ex China. This seems quite a nice little module that could be used as follows:

On TX:? control drive level to the pre-driver stage

On RX: as an RF gain control (selectable in the menu and using the encoder to control 32 steps from 0dB to 31dB of attenuation)?

AND

??? ??? ??? as part of an AGC circuit to reduce gain for strong signals.

I have summarized the discussion of all the options for addressing variable output power from the ?BITx in a news article on ubitx.net here:

I ordered a couple of the modules, and I will tell you the outcome of my experiments in 2-3 months time.? It takes a while for parcels to arrive from China down here.?? Somebody else might beat me to it hopefully (like they did with the little mic compressor/noise gate chip) and can let us know how this scheme works!

BTW - if you use two modules in series you can get 62dB of attenuation! That would be great for AGC control!

73?? Mike ZL1AXG

开云体育

I usually get my orders within a week. For the connectors, you need to look for the 2500 series wafer connectors:

--
Karl Heinz - K5KHK

开云体育

开云体育

Sorry......

That's not the Tayda I have ordered from?

I have never had Tayda take over? a week?? And yes they also sell on eBay with Free Shipping.

But the eBay prices from Tayda are more than ordering direct.

So have you had Long delivery time?

I have no investment in them!

Mike, WA6ISP

They were actually out of them when I ordered these. ?It usually takes me just as long (longer sometimes) to get stuff from Tayda as it does out of Hong Kong or Mainland China and it's the same exact stuff. ?I actually get it cheaper off of eBay. ?But then you must work for Tayda as much as you plug them - LOL.

Jim?

------ Original Message ------

From: "Michael Hagen" <motdog@...>

To: [email protected]

Sent: 2/22/2018 9:10:30 PM

Subject: Re: [BITX20] wiring harness bitx40

Don't Forget Tayda for all Molex style connectors and pins and headers!

What a deal they have!

Mike, WA6ISP

On 2/22/2018 6:53 PM, Jim Sheldon wrote:

I have just the 8 pin ones, not the 2 and 3 pin.? I bought them in male/female sets out of Hong Kong off eBay as they were cheap enough and the only place I could find them in stock anywhere.? I mainly need the male PC board mount ones so the 8 wire females (already cabled) are mostly surplus.?

W0EB

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

开云体育

Don't Forget Tayda for all Molex style connectors and pins and headers!

What a deal they have!

Mike, WA6ISP

I have just the 8 pin ones, not the 2 and 3 pin.? I bought them in male/female sets out of Hong Kong off eBay as they were cheap enough and the only place I could find them in stock anywhere.? I mainly need the male PC board mount ones so the 8 wire females (already cabled) are mostly surplus.?

W0EB

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

I have just the 8 pin ones, not the 2 and 3 pin.? I bought them in male/female sets out of Hong Kong off eBay as they were cheap enough and the only place I could find them in stock anywhere.? I mainly need the male PC board mount ones so the 8 wire females (already cabled) are mostly surplus.?

W0EB

How many do you need?? 8 wire?? I have a bunch for the uBITX that I'm not going to use.? I have a goodly handful of 8 wire female plugs with wires already attached, color coded ALMOST like the uBITX.? From left to right, Violet, Blue, Green, Orange, Yellow, White, Red and Black.? I bought them as pairs, wired female and PC mount male (I need most of those but could spare one or two if you need them too).

Look me up on QRZ and email me -? I won't hurt your pocketbook too bad.

Jim Sheldon, W0EB

For uBitx and Bitx40 connectors, google for "KF2510"
Originally by Molex, I believe.
You will likely be adding the wires, I haven't seen complete harnesses, but then I haven't looked very hard.
Here's an old thread:??/g/BITX20/topic/5162271

Ok Thanks? That clears that up
--
73, W9KJO
Walter

开云体育

Well, the Encoder is usually handled differently on UBit vs BitX.

When changing from a pot to an Encoder on BitX,? I went for the interrupt routine method.

I added 10K pullups and 0.01uF debounce caps.? The inputs are put on interrupt pins.

Ash handles the Encoder different in uBit.

There is a routine that reads them as inputs?? I think?

73's

Mike, WA6ISP

Is this for the MBITX?

Could someone draw this up?? I'm not sure I understand what is being described.? A little schematic would clear it right up.

--
73, W9KJO
Walter

-- 
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID  "MotDog@..."
Mike@...

anyone know where to get replacement harnesses for the bitx40 ... ?

Is this for the MBITX?

Could someone draw this up?? I'm not sure I understand what is being described.? A little schematic would clear it right up.

--
73, W9KJO
Walter

As N5IB said, the ALPS information is good to know. I've been involved with the "RadI2Cino" pretty much from the beginning and the 10K in series with .01uf to ground (.1 on the ones I've built myself) helped a bit.

I've built an open frame "Test Bed" where I can plug any Raduino card in and run it through it's paces so I added another pair of 10K, 1/8 watt resistors from VCC to the two encoder inputs on the board. (I did these on external plug connections I have on the test bed).

WOW! This settled the really cheap and modified (to take the detents out) encoder on the test set right down. Tuning is extremely smooth and I don't notice ANY digits showing up and then backing up again as it did before.

I can highly recommend adding a 10K external pullup to both the encoder A and B inputs as well as an additional 10K in series with .1uF capacitor to ground on both the A and B inputs to the Raduino card.

It was a nice surprise addition and I won't leave them out again.

Jim Sheldon - W0EB

ALPS, a maker of rotary encoders, recommends 10K pullup to Vcc, then 10K in series with 0.01 uF to ground.
The internal pullup in the ATMega is loosely specified - somewhere in the tens of K, max 50K

On our "RadI2Cino" we provided pads for the RC series pair to ground, but not for any additional external pullup.

N5IB

Thanks Mike.
73, John