[time-nuts] LPRO101 Lamp Exciter Frequency

[Roberto Barrios]

> Date: Tue, 3 Nov 2009 23:05:30 +0100 (CET)
> From: "iovane at inwind.it" <iovane at inwind.it>
> Subject: Re: [time-nuts] LPRO101 Lamp Exciter Frequency
> To: <time-nuts at febo.com>
> Message-ID:
> <25191930.94401257285930323.JavaMail.defaultUser at defaultHost>
> Content-Type: text/plain;charset="UTF-8"
> 
> rbarrioss at msn.com wrote:
> Date: 26/10/2009 7.54
> 
> >Yes, everything I've seen 
> points me to think that the oscillator runs at 140Mhz and not 70. .......
> >
> 
> >Please, come back to us when you measure the exciter frequency on your LPRO, 
> thank you.
> 
> Roberto,
> 
> I've done the check. Please excuse me for the delay due 
> to the fact that I have 
> my stuff spread across two locations 250 Km apart. 
> Last week-end I fetched a working 
> Rb and brought it here where I have spectrum 
> analyzers.
> 
> No 70 MHz signal at all, you were right. What I can see is 60 MHz, 
> its 120 MHz 
> harmonic and then the about 145 MHz from the lamp ignition 
> oscillator.
> 
> Probably PE1FBO was misled by me, and I, on my hand, had accepted 
> the occasional 
> 70 MHz reading (made with an hand held counter !) being biased 
> by the FRS specs.
> 
> I apologize.
> 
> 73,
> Antonio I8IOV


Hi Antonio,

 

Thank you for taking the time to confirm this. I purchased a second (working) LPRO and it also confirmed that exciter frequency is actually around 150Mhz, as you just saw. Clapp oscillator equations showed that frequency should be much higher that 70Mhz but you never know...It's nice we've been able to clarify this point... it took quite a bit of effort (and risk) to modify the circuit to resonate exactly at 70Mhz, just to find that the lamp would not ignite :-)

 

I've made a few other interesting discoveries that would make for a nice LPRO Repair Guide revision. I'll share the details when I've got everything properly tied.

 

Thank you,

Roberto EB4EQA

 		 	   		  
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