WD8BXS
alter Hase
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V6 new issue
« on: 04. June 2018, 21:49:21 »
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Just finished a V6 build, all works well, but, getting high current on 40 meters only. Almost 3 amps for 9 watts.
Other bands are about 1.9 amps for 10 watts.
Any ideas ?
I removed C78 and no change.
Thanks,
Chuck
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Thanks,
De WD8BXS vy 73
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DF5LI
alter Hase
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Ich liebe meinen SParrow !
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Re:V6 new issue
« Reply #2 on: 05. June 2018, 08:44:49 »
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You have removed C78, then the only remaining components for 40 m are in the 40 m LPF. You should carefully check those L's and C's. Also listen to the "Click"" of the relays, when you switch to 40 m. And have a look on RFC 5 and 6. Maybe the drivers are oscillating on 40 m. I always change these chokes to a lower value with a higher self-resonating frequency.
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| « Last Edit: 05. June 2018, 08:51:00 by DF5LI » |
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73, Harri
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WD8BXS
alter Hase
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Re:V6 new issue
« Reply #3 on: 05. June 2018, 14:35:57 »
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Interesting note about RFC5 and RFC6, what would be a solution for a replacement?
Thank,
Chuck
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De WD8BXS vy 73
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WD8BXS
alter Hase
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Re:V6 new issue
« Reply #5 on: 05. June 2018, 19:30:19 »
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By signal scope do you mean spektrum analyzer?
I do not have one of those, sadly
If I use "O" scope it looks clean.
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De WD8BXS vy 73
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WD8BXS
alter Hase
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Re:V6 new issue
« Reply #6 on: 05. June 2018, 19:56:49 »
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Changed RFC5 and RFC6--No Change
Changes LPF coils--No Change
Changed the Finals--No Change
Changed R81 and R82 to 100 Ohms -- No Change.
Still drawing almost 3 amps on ONLY 40 meters.
Scratching my Head hihi
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Thanks,
De WD8BXS vy 73
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WD8BXS
alter Hase
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Posts: 286
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Re:V6 new issue
« Reply #8 on: 05. June 2018, 21:59:37 »
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I do not understand.
Do you mean that I should see the same amplitude before the LFP and after the LPF ?
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De WD8BXS vy 73
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WD8BXS
alter Hase
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Re:V6 new issue
« Reply #10 on: 06. June 2018, 10:47:17 »
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"As I understood you have correspondent power in / power out combinations on every band except 40m. Right?"
NO, I do have power out on 40 meters!, The drive levels in the PA menu for 5 watts look very similar on all lower bands, BUT on full power, the 40 meter setting has to be 2 TIMES the value of the others and it will not go above 8.5 watts!
"If not you must take a look at the signal coming out of PA. Is there something oscillating e.g. You have to look at the signal with an oscilloscope."
I did touch the scope to R26 and to C58, signals look clean.
Thank you for your patience with me, I am still learning hihi
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De WD8BXS vy 73
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DF5LI
alter Hase
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Ich liebe meinen SParrow !
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Re:V6 new issue
« Reply #11 on: 06. June 2018, 11:35:07 »
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Very strange! You have changed L14, L18 and L22? Did you have checked the caps in the LPF? Try to make a bridge over the entire LPF for 40m. Remove C46 and C58, L14 and L22. Then solder a wire from the left pad of L14 to the right pad of L22.
So there is no LPF for 40m. If the problem persists, we have to look at T6 and T7....
(a friend of mine has managed it to solder 100nF instead of 470 pF for C57. The results are similar to your problem ;-))
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73, Harri
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WD8BXS
alter Hase
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Re:V6 new issue
« Reply #12 on: 06. June 2018, 12:49:43 »
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Hello Harald,
I put the jumper in across the LFP as per your suggestion, and that fixed it!!
I put NEW caps in and re-made the coils, re-installed, and back to the same issue!!
VERY strange!! This is my 23rd build, not a novice to the coil winding etc... hihi
Thanks for your suggestions, keep them coming!!
de Chuck WD8BXS
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De WD8BXS vy 73
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WD8BXS
alter Hase
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Re:V6 new issue
« Reply #13 on: 06. June 2018, 15:53:38 »
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I just changed C58 to 100pf, that made everything look good!
What do you think??
Chuck
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Thanks,
De WD8BXS vy 73
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DF5LI
alter Hase
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Ich liebe meinen SParrow !
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Re:V6 new issue
« Reply #14 on: 07. June 2018, 11:40:09 »
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I think, you have made the cut-off frequency (and perhaps the output impedance) of the LPF a little bit higher, and now the 7 mc-signal will pass the filter. I always measure the inductivity of the coils with my L-meter and sometimes i have to reduce the number of windings a little bit (1 winding less). The T37-2 cores sometimes have different AL-specifications (+- 20%).
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73, Harri
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