Still two orders of magnitude off.

My typo, I used a pair of .22 pF for .44pF (closes I could get).?

I have a suggestion when someone suggests a vendor.? The idea came to me when Vince found a 1/4" shaft audio pot (great find by the way).

On Fri, Dec 29, 2017 at 03:39 pm, Vince Vielhaber wrote:

Just heard back from Adafruit. This pot: for $1.50 is an audio taper and has a 6mm shaft (1/4" is 6.35mm).

I've never ordered from adafruit because for the longest time they wouldn't ship usps to me so the shipping was a killer.? I see they finally will ship usps.?? What else should I buy from them?? I'm not talking about the standards I can find anywhere but it seems like each vendor has a few things that are very difficult to source anywhere else.? An example would be the M7 nuts for the chinese encoders that Jameco seems to have the market cornered on.? Like most of us I have paid more in shipping than the part costs just to get something I need only to remember a day later I should have ordered something else or spent more time filling my cart on Tayda to hit $5 than it took to find what I was looking for in the first place.? So my suggestion is this, if you are naming a vendor try to also list a few things that are great cart fillers or hard to find anywhere else.? I realize with everyone chasing different projects this isn't always practical or useful, but it might be.

470pf? in an NPO or C0G or silver mica would be ideal.
Voltages there are quite low, less than 5v, so most any voltage rating.

> I've temporarily repaired with a pair of .22uF in parallel.

That would give you 0.44uF, which is 440000pF.?
Not good, I'd be surprised if it worked at all.



On Sat, Dec 30, 2017 at 08:07 pm, D. Daniel McGlothin KB3MUN wrote:

I need part specification for BITX40 capacitor C7. I know it is a 470 pF. Is it an NPO? what voltage rating?

I need part specification for BITX40 capacitor C7. I know it is a 470 pF. Is it an NPO? what voltage rating?

I need part specification for BITX40 capacitor C7.  I know it is a 470 pF.  Is it an NPO?  what voltage rating?

This week past, I put together my BITX40.  Observing very weak audio signal, I was following the receiver diagnostics video (  ) and found unexpected behavior when probing the band pass filter.  I also found that I have a bad audio jack linking the headphone jack and the speaker (probably a overheating problem).

Anyway, I was re-soldering the BPF inductors (L1..L3).  While there, I decided to resolder the capacitors (C1..C7) as well.  C7 came off when soldering one end (the other end "broke" off, and the chip came off on the iron).

I've temporarily repaired with a pair of .22uF in parallel.

Thanks,
Daniel KB3MUN

Hi Jerry,

Sorry for the delay (holidays you know).??

I do have a number of the 100N50 resistors and find that they work great.

Yes, I saw the notes from Jack but I am unclear about the?operation.? Software apparently is in his book and likely available in QST sometime in 2018.??

Can I just use the circuit w/o the nano,?I assume the resistor divider is for sampling by the nano???If?I connect the rig across the 50 ohm load and measure the voltage across the capacitor, what is the relationship of voltage to power (is it simply V^2/R)?

---

From: [email protected] <[email protected]> on behalf of Jerry Gaffke via Groups.Io <jgaffke@...>
Sent: Tuesday, December 26, 2017 11:39 PM
To: [email protected]
Subject: Re: [BITX20] Very low power output (BitX40), everything appears to be working but setup driving me crazy!

?

How reasonable do you want to be on the cost thing for your wattmeter?

Could build a dummy load with wattmeter along the lines of the one Jack described, reads peak power:
? ??/g/BITX20/message/36955
In post 37017 Mike describes using these $0.10 resistors:? ???So you need a 50 ohm load resistor of some sort plus a diode (a 1n4148 or 1n914 would do) plus 2 resistors and a cap.?
Use your DVM to measure the voltage from the cap.? Total cost is around $1 from Mouser, plus $10 shipping.

Some really nice 50 ohm RF loads on ebay, need an awful big heatsink if giving it 250W
I've got some of these on order, should show up in a month or so.
? ??

1Pc x Load Resistance RFP 250-50 250W 50 Ohm 250N50 TC RF Resistors. High-frequency high-frequency dummy load 250w 50 Ohm. 3, Silver microstrip pin as much as possible with the input signal parallel. | eBay!

Alternately, no dummy load but include an inline SWR meter for daily use with the rig:
? ? /g/BITX20/message/36987

Re: Dummy - groups.io groups.io No, it's not meant to be left in line, as it sucks up all the power and is not a "sampling" wattmeter. Peter Parker had a really simple sampling as a tuning indicator ...

Cheapest solution:
Stick with the CB wattmeter, but ask local hams to check it against some better instruments.
It's probably just fine for what you are doing.

?Jerry, KE7ER



On Tue, Dec 26, 2017 at 07:53 pm, Gene Nitschke wrote:

Is there a good (reasonable cost) watt meter that would be better to use in these situations?

Can I just use the circuit w/o the nano,?I assume the resistor divider is for sampling by the nano???If?I connect the rig across the 50 ohm load and measure the voltage across the capacitor, what is the relationship of voltage to power (is it simply V^2/R)?