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Bypass attenuator on 50W Amp?
#50w
OK, The voltage applied to the 50W amp must be 20V (-+ reasonable margin) at 12-13V it will NOT DO 50W regardless of the drive level. Expected power at 13.8V is 25W at 40M and between 20-25W at 20M. T
OK, The voltage applied to the 50W amp must be 20V (-+ reasonable margin) at 12-13V it will NOT DO 50W regardless of the drive level. Expected power at 13.8V is 25W at 40M and between 20-25W at 20M. T
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ajparent1/KB1GMX
· #85423
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Enhanced QDX for 2 Meters .. Crazy?
#qdx
For VHF work (any mode) both end of the path have to have the same polarisation going from a horizontal yagi to a vertical is workable but less effective than both being the same. The only time I've h
For VHF work (any mode) both end of the path have to have the same polarisation going from a horizontal yagi to a vertical is workable but less effective than both being the same. The only time I've h
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ajparent1/KB1GMX
· #85421
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50 watt amp on 160
>>>I have RF all over in my attempts. <<< What does that mean?? Likely few have if any. The amp design hits 80M but a full octave below that may mean transformers and bypass caps may need revision for
>>>I have RF all over in my attempts. <<< What does that mean?? Likely few have if any. The amp design hits 80M but a full octave below that may mean transformers and bypass caps may need revision for
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ajparent1/KB1GMX
· #85175
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QDX and eliminating the laptop
My backup machine for FT8 (digital modes in general) is a Rpi3B+, hooked to a 10.1 inch color LCD with mouse and keyboard. Sound is handled by a USB sound dongle. It runs Raspbian linux and supports F
My backup machine for FT8 (digital modes in general) is a Rpi3B+, hooked to a 10.1 inch color LCD with mouse and keyboard. Sound is handled by a USB sound dongle. It runs Raspbian linux and supports F
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ajparent1/KB1GMX
· #85045
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Enhanced QDX for 2 Meters .. Crazy?
#qdx
Tom, Kits for 2M are rare as its very intolerant of most kit builders idea of short leads, have need to be critically tune coils and many more factors. Ever consider 2M repeaters (or 440)? Decent 5W H
Tom, Kits for 2M are rare as its very intolerant of most kit builders idea of short leads, have need to be critically tune coils and many more factors. Ever consider 2M repeaters (or 440)? Decent 5W H
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ajparent1/KB1GMX
· #85043
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Z-Match Design Question
#qdx
#z-match
Its there to filter the rectified RF (what the 1n4148 does) to cleaner DC. In higher powered cases its less essential but at lower power it can help with led brightness. Also the series resistor is so
Its there to filter the rectified RF (what the 1n4148 does) to cleaner DC. In higher powered cases its less essential but at lower power it can help with led brightness. Also the series resistor is so
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ajparent1/KB1GMX
· #84650
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EFHW from ARRL
>>>The main difference between the EFHW and dipole are the higher ground losses of the EFHW end close to the transceiver, which carries high voltage.<<< Fail, lets all stick to apples and apples. Comp
>>>The main difference between the EFHW and dipole are the higher ground losses of the EFHW end close to the transceiver, which carries high voltage.<<< Fail, lets all stick to apples and apples. Comp
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ajparent1/KB1GMX
· #84635
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Antenna matching, even the "experts" get it wrong.
Shirley, IF you give the talk I'll have to check it out. Takeaway items. Antenna matching networks are not required to have harmonic suppression. The goal is to present a acceptable impedance to the t
Shirley, IF you give the talk I'll have to check it out. Takeaway items. Antenna matching networks are not required to have harmonic suppression. The goal is to present a acceptable impedance to the t
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ajparent1/KB1GMX
· #84539
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EFHW from ARRL
Steven Dick 4:21am #84345 , Your posit on turns vs core size is valid to a point. IF your doing 20M and up 2/14 might actually be better but for 80M 3/21 or greater might be the winner. The problem is
Steven Dick 4:21am #84345 , Your posit on turns vs core size is valid to a point. IF your doing 20M and up 2/14 might actually be better but for 80M 3/21 or greater might be the winner. The problem is
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ajparent1/KB1GMX
· #84349
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50W PA - resistor and PCB traces problems
Charles Johnson KF4AYT Because you apparently do not understand series and parallel circuits. R4 is in parallel with the winding of T1, that has a very low resistance and you never See R4 with a meter
Charles Johnson KF4AYT Because you apparently do not understand series and parallel circuits. R4 is in parallel with the winding of T1, that has a very low resistance and you never See R4 with a meter
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ajparent1/KB1GMX
· #84347
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Tractor Self-Repair
WHY is this in the QRPlabs forum???? Allison ------------------------------- Please reply on list so we can share. No private email, it goes to a bit bucket due to address harvesting
WHY is this in the QRPlabs forum???? Allison ------------------------------- Please reply on list so we can share. No private email, it goes to a bit bucket due to address harvesting
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ajparent1/KB1GMX
· #84316
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EFHW from ARRL
The poster didn't say 80 and warc or 40 and warc. His words on bands... >>>They claim coverage from 10 to 40 on the traditional ham bands, but not 30, 17, or 12. <<< Look up the antenna and they say h
The poster didn't say 80 and warc or 40 and warc. His words on bands... >>>They claim coverage from 10 to 40 on the traditional ham bands, but not 30, 17, or 12. <<< Look up the antenna and they say h
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ajparent1/KB1GMX
· #84315
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50W PA - resistor and PCB traces problems
You cannot measure R2 and R3 or R4 in circuit as they are effectively across each other and T1. Allison ------------------------------- Please reply on list so we can share. No private email, it goes
You cannot measure R2 and R3 or R4 in circuit as they are effectively across each other and T1. Allison ------------------------------- Please reply on list so we can share. No private email, it goes
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ajparent1/KB1GMX
· #84229
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50W PA - resistor and PCB traces problems
You did something to cayuse a high current short and burnt off the traces. THe fix for those burned off traces is fine wire (#28 or so) to bridge the burnt connection. Allison ------------------------
You did something to cayuse a high current short and burnt off the traces. THe fix for those burned off traces is fine wire (#28 or so) to bridge the burnt connection. Allison ------------------------
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ajparent1/KB1GMX
· #84228
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QCX+ grounding
The antenna should be grounded before entering the shack. The big static charge (lightning) is best dealt with outside rather than trying (unsuccessfully) to pass it though the radio. If the coax is g
The antenna should be grounded before entering the shack. The big static charge (lightning) is best dealt with outside rather than trying (unsuccessfully) to pass it though the radio. If the coax is g
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ajparent1/KB1GMX
· #83706
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Measuring harmonic radiation
First measuring at L4-C4 is sorta meaningless. If you put a scope probe there you add (typically 7-12pF) capacitance and detune the node. That and you do not put that point of the circuit directly to
First measuring at L4-C4 is sorta meaningless. If you put a scope probe there you add (typically 7-12pF) capacitance and detune the node. That and you do not put that point of the circuit directly to
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ajparent1/KB1GMX
· #83702
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Si5351A Synth spurious
Spurs on crystal osc... Likely bad rock or maybe insufficient loading. I take it that you replaced the SI5153 rock. Spurious emission regs, See FAR Part 15, Part 95, Part 97 lots of stuff there and it
Spurs on crystal osc... Likely bad rock or maybe insufficient loading. I take it that you replaced the SI5153 rock. Spurious emission regs, See FAR Part 15, Part 95, Part 97 lots of stuff there and it
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ajparent1/KB1GMX
· #83133
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VFO/ Sig Gen with HW-101
I forgot... With the D-VFO it may require a switch to "zero out" the frequency error due to sideband selected and the heterodyne oscillators. In some HW101s there is noticeable drift from the crystals
I forgot... With the D-VFO it may require a switch to "zero out" the frequency error due to sideband selected and the heterodyne oscillators. In some HW101s there is noticeable drift from the crystals
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ajparent1/KB1GMX
· #83132
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VFO/ Sig Gen with HW-101
It will need an amp as well. Allison ------------------------------- Please reply on list so we can share. No private email, it goes to a bit bucket due to address harvesting
It will need an amp as well. Allison ------------------------------- Please reply on list so we can share. No private email, it goes to a bit bucket due to address harvesting
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ajparent1/KB1GMX
· #83130
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Si5351A Synth spurious
For low power its -43DBC, for VHF its -53dbc Where he -60db number comes from High power VHF (more than qrpp). Measurement I've made on various SI5351 boards with one oscillator output in use easily e
For low power its -43DBC, for VHF its -53dbc Where he -60db number comes from High power VHF (more than qrpp). Measurement I've made on various SI5351 boards with one oscillator output in use easily e
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ajparent1/KB1GMX
· #83098
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