Re: Cricket 40


John Lonigro
 

Frank:

I powered my KX3 this morning first with an Astron linear supply.  I turned off the AGC, set the radio to 7040 kHz, and cranked up the audio gain to max.  There was no antenna on the radio, so all I heard was background noise.  Personally, the hum from the Astron sitting a foot away was about as loud as the noise coming from the radio.  Next, I removed the Astron supply and attached my 18 volt string trimmer battery running a buck converter that I bought online.  The voltage was set to 13.2 volts.  I can't remember where I bought the converter or what brand it is.  If you'd like, I can look at the converter PCB and see if there are any identifiable markings on it.  I think I paid $3 or $4 for it when I bought it a couple of years ago.  Anyway, I honestly couldn't tell any difference in noise level when using the two different supplies.  I'm sure if you put a scope on it, you could see a difference.  According to that informative video we were pointed to a few days ago, the noise gets worse as the load increases.  The KX3 current drain on receive isn't very much but I suspect it's a whole lot more than that of a Cricket 40.  Otherwise you couldn't power it long with a 9 volt battery.  Furthermore, I suspect a Cricket 40 on transmit doesn't draw much more current than the KX3 on receive does.  So without having a Cricket 40 (or an antenna), I would think you'd be OK.  You aren't risking much money in either case, about the price of a high quality 9 volt battery.

I hope this data point helps.  If you need further information, let me know.

72,

John, AA0VE


On 1/2/20 5:40 AM, John Lonigro via Groups.Io wrote:
Frank: 
I don’t have a cricket. I will try to do a comparison using my kx3 later this morning and will let you know. I don’t have an antenna put up right now though. 
John AA0VE




On Jan 1, 2020, at 9:29 PM, Frank Perkins <N6CES.r@...> wrote:


Hi John,
Just curious if there is any noise radiation from the buck as compared to a linear voltage regulator.
Frank N6CES

On Wed, Jan 1, 2020, 9:57 AM W6BOW via Groups.Io <DBuckter=aol.com@groups.io> wrote:

Buck converter tutorial, YouTube ...
https://youtu.be/CEhBN5_fO5o

Don - W6BOW


On Jan 1, 2020, at 10:04 AM, John Lonigro <jonigro@...> wrote:

You can purchase a "buck converter" for very few dollars from multiple sources.  It will convert 12 volts to whatever voltage you need.  I don't know about shipping charges, but the converter itself costs on the order of the price of a name brand 9 volt battery.  I use one to convert an 18 volt Li-ion battery for my string trimmer to 12 volts for my QRP rigs.  I don't need my string trimmer more than a few months each year.  The converter, which easily fits in an "altoids" or similar box, makes the battery useful all year long.  And it seems like a pretty clean voltage too. 

72, Happy New Year, and don't forget the Second Sunday Sprint coming up in about 11 days,

John, AA0VE

On 1/1/20 8:54 AM, Viktors Miske wrote:
I came across this the other day. Might help.
https://4sqrp.groups.io/g/main/message/15983?p=,,,20,0,0,0::relevance,,And+a+Cricket+can,20,2,40,7587611


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