Carl, I still need help & I have a question.

[Tilladude]

Carl, first let me apologize for the Mr. Carl thing my stupid gene took over that day. Now then I'm still having a problem toasting R10 and I also noticed that Q3 is getting awful warm as though it's in max conduction. I tried Qiaozhi's suggestion but the problem persists.

On page 8 of the manual on the HH, center column about damping res. "but for the 500uH coils described in the coils section." The coil you mention is a 10" with 26 trns.
of 26 ga. wire which produces a coil in the mid 300uH range. Is the 500uH a typo or are the coil calculators I'm using binarilly challenged.

Many thanks,
Dennis
In sunny but cool Tillamook

[WM6]

On page 8 of the manual on the HH, center column about damping res. "but for the 500uH coils described in the coils section." The coil you mention is a 10" with 26 trns.
of 26 ga. wire which produces a coil in the mid 300uH range. Is the 500uH a typo or are the coil calculators I'm using binarilly challenged.

Hi Dennis

For debate and not to substitute Carl's expert view.

Real coil inductance depend on how (tight before all) you wind turns of wire together. This can vary even 100uH in described coils. Furthermore it depend on used inductance meter too, you do not get the same result if measured frequency of inductance meter is 100kHz or it is (the best) 1kHz. Depended on used inductance meter results can vary even 100uH too in such case. And not least (software) coil calculator are not the same (not the same formulas used, with not the same parameters). Such calculations can vary even 100uH too.

Fortunately, PI detectors are very forgiving regarding coil inductance and can well survival real tolerances in coil inductance. Not with same depth characteristics, but can survival. In first line it is important to chose adequate damping resistor to real inductance of your coil. To reach this goal we need a scope and try to get right decay signal shape on display .

[Tilladude]

WM6<

I had to blink my eyes and now munch on a few words. I wound a 10" coil with 27 turns of 24 ga. wire, (didn't have any 26 ga. & 28 would have too high a resistance) I laid on a layer of 1/8" spiral wrap followed by a layer of 1/4" spiral wrap and then measured it.

My meter is a Tenma CRL meter using 1KHz for inductance. The online calc said 27 turns would be .3621mH @ 1.8221 Ohms but the Tenma said .530mH @ 2.05 Ohms, go figger. Now I need to put the shield on it and see what happens when it's hooked up to the the unit.

TTFN,
Dennis

[Carl-NC]

Dennis,

Sorry, actually I missed your last post. Any coil from 200-500uH should work fine on HH.

I suggest you remove the coil and run it with just the damping resistor. Then do your debugging. Make sure the gate is getting pulled all the way off. Make sure the duty cycle looks right. If you can take photos of waveforms & post them then we can help more. Or just bring it down to Sweet Home!

No, haven't been to Tillamook yet, dying to see the blimp hanger (I'm a huge warbird fan) and get some tasty cheese.

- Carl

[Tilladude]

Once upon a once there were two hangars but a silly person allowed the storage of hay in one of them, physics and nature did their thing and poof, now there is only one hangar.

Crazy thing is that for many years there was a wood products mill in that hangar with a wigwam burner just outside and never a problem was had.

Would you believe that since I retired from the service and moved back to Tillamook (spent 7 yrs. here on active duty) and I have yet to go out and see those beautiful old birds, shame on me.

I'll give your suggestions a whack and see what happens. Only tried once to take pics of my scope and didn't have a lot of luck, I'll do some experimenting and see if can perfect the technique.

Many mucho thanks,
Dennis

[fidamohd82]

i have the same R10 problem so can you give any advice

[Qiaozhi]

i have the same R10 problem so can you give any advice

Check out Carl's reply in a previous post.

[Tilladude]

After a long sabbatical I am picking up my Hammerhead and trying to figure out what is happening. Carl... I was going over the the manual again and noticed something that raises a question, namely, what is the correct circuit configuration for the gate input to Q3? In the schematic on pg.2 you show a jumperable connection taking the gate input from either the collector of Q2 or between R8 and R9. At the bottom of pg.3 you show the fig.5 Oscillator & Transmit in which R7 & R8 are deleted and the gate input is taken off the emitter of Q2. Which is the right way to go, hopefully this might stop the frying of R10?

Tilladude aka Dennis

Addendum: In lookig over the board more closely I don't find R7 so apparently that part of question is resolved.

[Tilladude]

Lets start with an oops, I found R7 (old eyes). Now having found R7 I removed it and R8 and configured as per. fig. 5 and fired it up, no smoke. Then I hooked up a coil (420uH & 2.4 ohms) and well another one, ohm resister, bites the dust. Time to cook some dinner. Dinner done, it was tasty, replaced the crispy critter, last one, and disconnected the coil laid on the voltage with crossed fingers, no smoke. I'm not going to reconnect the coil until I can lay in a supply of 1 ohm bullets.

Dennis