[HBQRP] VFO Complete

[Darrel Swenson]

Hi Steve...

I don't have a lot of time to experiment tonight, but I'm guessing the
frequency if off because of the 27 turns instead of 29.  If I remember
toroid theory right... the number of times the wire goes through the hole in
the core is more critical than the size of the wire.  29 turns of any size
wire (small enough to get 29 turns on the core) should get you near 3 MHz.

Regarding Q2... 2.75 - 1.695 = 1.055V is a little high for the base emitter
voltage drop... it should be .7 +/- .1 or so.  I'm not sure why... maybe
your voltmeter is loading the circuit slightly.  As long as it is
oscillating... I don't think I would worry about it yet.

I'm off to the church to fix the sound system AGAIN... [I think there is a
turkey in there somewhere :)]

I will try to experiment a bit later tonight or this weekend with different
cores and see what I get.

72... Darrel...


-----Original Message-----
From: hbqrp-bounces at mailman.qth.net
[mailto:hbqrp-bounces at mailman.qth.net]On Behalf Of ssellmeyer
Sent: Tuesday, November 22, 2005 3:20 PM
To: Midwest Homebrewers Group
Subject: [HBQRP] VFO Complete


And the toroid saga continues................

This afternoon I was able to wind 27 turns of # 22 gage wire on to the
T-50-6 big yellow toroid core. That was the maximum amount of turns I found
that I could wind on it. I'm sure 29 turns of # 26 would have fit easily
versus the kit supplied # 24.

My power on readings were as follows:

1.  Using a Radio Shack frequency counter and touching the base of Q2 gave
me a frequency readout of 2.625 Mhz. The Elmer 101 book says Approximately 3
Mhz. Hmmmmm, waiting for advice or comments from the rest of you on this.
Good or bad ???
Using my RF probe gave me 1.250 vdc on the base. This is NOT a calibrated
probe by the way so I have my doubts about it's accuracy.

2. Not using the RF probe but just using the regular meter probes I have :
Q2 base voltage of 2.257. Elmer says 2.17. Looks good to me.
Q2 emitter voltage was 2.411. Elmer says 2.4. Again looks good.

3. With L1 jumpered:
 Q2 base was 2.75. Elmer says 2.13.  Hmmmm ??
 Q2 emitter was 1.695. Elmer says 1.5. Hmmm again ??

Maybe I have a "strong" Q2 here??

Now to start reading and figure it all out ! !  Wish me luck on the
understanding part ! !

Steve/WBØQQT




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