Date   
Re: Bitx40 All done

W1PJE
 

Do you have to be careful when drilling the acrylic to avoid cracking?

Phil, W1PJE

Worth it!

Dexter N Muir
 

I'm just getting started with my BITX40 kit, without Raduino (at present). First power-up was *incredibly* noisy. with audio seemingly OK. I've since ratted a 1000uF/16V electro cap and 27 ohm (2W?) resistor from a defunct PC power supply and used them to filter the power supply (a junk-sale purchase never since used). Whoopee (I don't Yahoo)! Clean audio - minimal hiss at full volume, indicating healthy rig. No antenna yet, so the rest still unknown, but I've now verified the purchase was worth it! Thanks, Farhan and crew, and folks and hints from here ...

Re: noise

John Sharpe
 


Hi, Jerry,

very weird is a good description.

As you suspected, the rig did not want to transmit with the 10 nf capacitor across the antenna.

I moved the capacitor to C1 - added it parallel to C1 - and it fixed the receive audio, but again did not want to transmit with any power.

(I thought C1 would be out of circuit during transmit, but I’m not great at reading the schematics!)

Back to square 1, I removed the capacitor and I can transmit ok, but back to noisy receive.

I checked C1 and it reads as 1200 pf instead of the 470 pf on the schematic. That might be my inaccurate capacitance meter.

The Bitx has had a big burst of RF from a nearby transmitter, maybe that upset something.

I’ll keep experimenting. I do have a good antenna (ZS6BKW) so plenty of signal going into the Bitx.

John, VK2VOL




On 8 Jul 2017, at 12:32 am, Jerry Gaffke via Groups.Io <jgaffke@...> wrote:

My thought is that this is very weird.

I'd be checking all those connections around the antenna with an ohmmeter.
Make sure everything you think is connected is really connected.

If you want to try transmitting with the rig in such a questionable state, 
maybe start out with a 10v power supply into the IRF510 and increase it to 12v 
only if a watt or so is getting through to the dummy load.  If you do have a bad
connection at the antenna BNC, the high SWR could blow the IRF510.
Especially if you are feeding the IRF510 more than 12v.

Jerry



On Fri, Jul 7, 2017 at 07:21 am, John Sharpe wrote:
The breakthrough stopped (surprisingly) when I grounded the centre contact of the antenna input. 7mhz  SSB signals came through fine!
 

A suitable case ?

 

This with a proper bezel can give the Bitx40 a great look!

https://www.banggood.com/RD-DP-And-DPS-Power-Supply-Housing-2-Kinds-Aluminum-Housing-Constant-Voltage-Current-Casing-p-1146253.html

73

--
Raj, vu2zap
Bengaluru, South India.

Audio Instability Cure

 

I had a low level buzzing sound in my Bitx40 when the volume was at a low level.

I disconnected the center brown lead of the volume control and added a 10K
resistor from the pot to the wire and problem solved.

Cheers

--
Raj, vu2zap
Bengaluru, South India.

Re: BITX40 Microphone options

 

On my analog VFO board #66, I measured across C107 - a level of 500+ mV pp gives full power with the level control
R136 midway.

With the supplied mic I can't get the power while speaking in a normal level. With a normal voice I should be able to
see 3-4 watts!

Raj, vu2zap


At 08/07/2017, you wrote:
On Thu, Jul 6, 2017 at 07:24 am, Raj vu2zap wrote:
With my lung capacity down I can't do "haaaaloo" level of yelling anymore so I am using an amped motorola mic.

What voltage (Vpp) do you look for going into the bitx's mic in?

Re: Bitx40 All done

 

Winner!


At 07/07/2017, you wrote:
I think some projects look kinda cool with a clear case.




Jack, W8TEE

Re: BITX40 Microphone options

Andrew Kasurak
 

On Thu, Jul 6, 2017 at 07:24 am, Raj vu2zap wrote:
With my lung capacity down I can't do "haaaaloo" level of yelling anymore so I am using an amped motorola mic.
What voltage (Vpp) do you look for going into the bitx's mic in?

Re: 80m hexfet power amplifier by W7ZOI

Richard Andrew Knack
 

I had my WA2EBY toroids wound for me by the same guy who does the toroid sets for Elecraft, to Elecraft's approved standards. I am waiting for the rest of the parts to arrive from Mouser, with the exception of the SMD resistors, which are on order from China. The ones from Mouser are on back-order, and won't arrive until NOVEMBER (!), and I really don't want to wait quite that long...

Rich
KC8MWG



On Friday, July 7, 2017, 9:04:32 PM EDT, Jack Purdum via Groups.Io <econjack@...> wrote:


Diz's company, Kits And Parts, is a gold mine for hard-to-find caps and toroids. A friend of mine has one of his One Watters and it's a fun little rig. Keep him in mind when you're building.

Jack, W8TEE



From: Leonard <dredger@...>
To: BITX20@groups.io
Sent: Friday, July 7, 2017 8:23 PM
Subject: Re: [BITX20] 80m hexfet power amplifier by W7ZOI


"Yeah, I forgot about Diz. He's good. He also has a toroid kit for the
WA2EBY LPF assembly, but not a cap kit as far as I know...

john
AD5YE"

Diz might put together a mica cap kit for the wa2eby amplifier. Someone would have to ask him. That's how the toroid kit came to be. I asked him. I bought all of the mica caps from Mouser.

Mouser parts list


Low pass filter test with network analyzer

Leonard




Re: 80m hexfet power amplifier by W7ZOI

Jack Purdum <econjack@...>
 

Diz's company, Kits And Parts, is a gold mine for hard-to-find caps and toroids. A friend of mine has one of his One Watters and it's a fun little rig. Keep him in mind when you're building.

Jack, W8TEE



From: Leonard <dredger@...>
To: BITX20@groups.io
Sent: Friday, July 7, 2017 8:23 PM
Subject: Re: [BITX20] 80m hexfet power amplifier by W7ZOI


"Yeah, I forgot about Diz. He's good. He also has a toroid kit for the
WA2EBY LPF assembly, but not a cap kit as far as I know...

john
AD5YE"

Diz might put together a mica cap kit for the wa2eby amplifier. Someone would have to ask him. That's how the toroid kit came to be. I asked him. I bought all of the mica caps from Mouser.

Mouser parts list


Low pass filter test with network analyzer

Leonard




Re: 80m hexfet power amplifier by W7ZOI

Leonard
 


"Yeah, I forgot about Diz. He's good. He also has a toroid kit for the
WA2EBY LPF assembly, but not a cap kit as far as I know...

john
AD5YE"

Diz might put together a mica cap kit for the wa2eby amplifier. Someone would have to ask him. That's how the toroid kit came to be. I asked him. I bought all of the mica caps from Mouser.

Mouser parts list


Low pass filter test with network analyzer

Leonard


Re: 80m hexfet power amplifier by W7ZOI

John Backo
 

Note that this particular design is for 80 meters.
It is tough to make the IRF530 work on 40 or 20 meters,
much less at 15 meters or above...

Use the IRF510 or equivalent (BUZ21/24/44) instead.

john
AD5YE

Re: Field Day 2017

Dexter N Muir
 

I'd consider each as a (varying with audio) resistor. At that rate, 3 in parallel would severely drop the available DC 'bias' power, and audio to any or all would be considerably reduced. Phase difference might also degrade things ...  I'd not bother.

Re: Speaker output low and garbled

John Backo
 

If fixing the connections does not help, the only thing to do
really is take it out and rewind the coil.

There is a lot of information around on how to do that. Watch out especially
for sharp edges on the ferrite toroid; they can and do short out the wiring sometimes.
You can file the edges, but it is a real chore. If the toroid is big enough, some wind it first with
tape to blunt the edges. That does little to the inductance and can help in avoiding
scraping the wire.

Use new wire -- the old wire is suspect. Usually something
around #24 magnet wire is what is used.

john
AD5YE

Re: Speaker output low and garbled

Michael Hagen
 

First, flux the connections and re-solder the connections.

Put the heat to it, maybe a bad solder joint or enamel was not all off the wire?

Just a guess?

The only other guess is that somewhere along a "Twist" something is shorting?


Mike, WA6ISP


On 7/7/2017 4:27 PM, Michael Davis wrote:
What is the best way to troubleshoot a toroid? My receiver is occasionally dead until I tap #? toroid, then it "jumps" to life. It remains working unless I accidentally hit that toroid again. It has 6 legs, 3 on each side soldered to/through the board. If I contact/tap each of the legs, there is no effect, so I think the problem is somewhere within the actual twists and coils. Can it be caused by the coil contacting the core and shorting? I am tempted to add some super glue to the coils while it's working and hope it stabilizes and eliminates the problem. 

Sent from Mike's iPad WA1MAD









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

Re: Speaker output low and garbled

Michael Davis <maddmd818@...>
 

What is the best way to troubleshoot a toroid? My receiver is occasionally dead until I tap #? toroid, then it "jumps" to life. It remains working unless I accidentally hit that toroid again. It has 6 legs, 3 on each side soldered to/through the board. If I contact/tap each of the legs, there is no effect, so I think the problem is somewhere within the actual twists and coils. Can it be caused by the coil contacting the core and shorting? I am tempted to add some super glue to the coils while it's working and hope it stabilizes and eliminates the problem.

Sent from Mike's iPad WA1MAD

Re: Field Day 2017

Michael Davis <maddmd818@...>
 

I have a bag of 30, tiny electret mic elements. I am thinking of connecting 3 in parallel electrically to see if It will improve or even work on my Bitx. Not sure how it will affect the input impedance match or audio level, if at all. Any thoughts?

Sent from Mike's iPad WA1MAD

Re: 80m hexfet power amplifier by W7ZOI

John Backo
 

Yeah, I forgot about Diz. He's good. He also has a toroid kit for the
WA2EBY LPF assembly, but not a cap kit as far as I know...

john
AD5YE

Re: 80m hexfet power amplifier by W7ZOI

John Backo
 

Mike:

As noted in the notes to the amplifier, Farhan uses ceramic capacitors AND
recommends a maximum RF voltage of 50v or so.

Mica caps are the best for such an application, but good ones
nowadays are very expensive. Dan's Small Parts and Kits has some.
He used to have many more but surplus ones are getting rare (n.b.).

Note that there are some some still made, but their quality is questionable,
at least from my experience. Mouser at least checks the quality...

john
AD5YE

Re: 80m hexfet power amplifier by W7ZOI

Vince Vielhaber
 

Did you try kitsandparts? They have 'em [depending on value] as low as 1.30 ea.

Vince.

On 07/07/2017 05:35 PM, Michael Hagen wrote:
What do folks do for the Mica Caps in all these band pass filters.

In the old days I had lots. I know they are great and usually over 200V.

But I see they are $2-3!! EACH! Ouch! Mouser has some.

Mike, WA6ISP


On 7/7/2017 12:36 PM, Jerry Gaffke via Groups.Io wrote:
If you have a Bitx40 it already has a comparable IRF510 linear amp,
giving around 20 to 25 Watts when powered from 24v.

I do like the LED RF detector on the output.

Jerry


On Fri, Jul 7, 2017 at 10:10 am, Daniel Isaza wrote:

Thanks a lot Farhan!
That's perfect, I'm building it today. What a nice and simple
circuit, respectable power output and also a great detailed post
on your blog. FB!
Dan.
--
Mike Hagen, WA6ISP
10917 Bryant Street
Yucaipa, Ca. 92399
(909) 918-0058
PayPal ID "MotDog@..."
Mike@...