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Post your Shack, Shop, Repair room / Re: Just getting off of the ground
« Last post by KE4EST on September 19, 2019, 05:44:13 PM »Looks great!
Recent Posts
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Post your Shack, Shop, Repair room / Just getting off of the ground
« Last post by guitar_199 on September 18, 2019, 05:36:32 PM »Been collecting gear for several years. Just now getting around to setting it up.
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Test Equipment / Re: RF sampler / demodulator for oscilloscope
« Last post by guitar_199 on September 18, 2019, 05:10:08 PM »Just to be sure, check the video. That 690 K, should be 690 ohm.
It is not a danger to equipment... it affects the accuracy.
With 47K nominal over 690 ohm in parallel with the load of 50 ohms (the cap is negligible at almost any RF) you get a voltage divider of 46.6/47046.6 which is almost exactly 1/1000 (.00099051 in fact) which is almost spot on -60 dB attenuation (60.08).
If you do it with 690K that 46.6 goes up to 49.99 which makes your voltage divider 49.99/47049.99 which works out to -59.47 dBm.
It isn't a huge difference but some users may value that.
According to my calculations, at 1000 Watts RF In the 47K would dissipate 1.06 watts. So use a 2 or 3 watt piece for safety.
At 1500 watts I show 1.59 watts so , again, a 3 watt piece, maybe 5 watts and that should handle it.
For other fun, 15K instead of a 47K would be -50 dB attenuation (15K will dissipate .33W at 100W RF/ 2w at 600w RF/3.3w at 1000W RF)
4.7K would be -40 dB (4.7K will dissipate .107w at 10w RF / 1.04w at 100w RF).
It is not a danger to equipment... it affects the accuracy.
With 47K nominal over 690 ohm in parallel with the load of 50 ohms (the cap is negligible at almost any RF) you get a voltage divider of 46.6/47046.6 which is almost exactly 1/1000 (.00099051 in fact) which is almost spot on -60 dB attenuation (60.08).
If you do it with 690K that 46.6 goes up to 49.99 which makes your voltage divider 49.99/47049.99 which works out to -59.47 dBm.
It isn't a huge difference but some users may value that.
According to my calculations, at 1000 Watts RF In the 47K would dissipate 1.06 watts. So use a 2 or 3 watt piece for safety.
At 1500 watts I show 1.59 watts so , again, a 3 watt piece, maybe 5 watts and that should handle it.
For other fun, 15K instead of a 47K would be -50 dB attenuation (15K will dissipate .33W at 100W RF/ 2w at 600w RF/3.3w at 1000W RF)
4.7K would be -40 dB (4.7K will dissipate .107w at 10w RF / 1.04w at 100w RF).
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Ham Radio Circuits and Repair / Re: RCI 2995DX NO POWER
« Last post by The Radio Shop on September 17, 2019, 09:02:55 AM »If you take another radio on the same channel can you hear it in the receiver when you key up the bad radio?
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Ham Radio Circuits and Repair / RCI 2995DX NO POWER
« Last post by Crambone on September 13, 2019, 12:30:14 AM »Ok guys I grounded test point 7 (TP7) to the RX Shielding Box, after I have no output power on any Bands, am, fm, cw....
It keys but shows NO power at all and when undereducated the needle on the RCI just bounces up and back down very quickly.
Any suggestions?
It keys but shows NO power at all and when undereducated the needle on the RCI just bounces up and back down very quickly.
Any suggestions?
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New member welcome / Re: Hi Fr0M EU France
« Last post by KE4EST on August 18, 2019, 11:02:09 PM »Welcome to the forum st3ph!
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New member welcome / Re: Hi Fr0M EU France
« Last post by The Radio Shop on August 17, 2019, 01:44:27 PM »Hi And welcome to the forum. Will be interesting to read your post.
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New member welcome / Hi Fr0M EU France
« Last post by st3ph on August 17, 2019, 12:56:19 PM »I am here to learn and also to help when I can.
young I was doing cb but had to stop a few years then the radio virus came back.
I have a few post but my preference goes to the old (solid strong reliable), nothing to envy to what came from -_-
73's all
& 88 YL;)
young I was doing cb but had to stop a few years then the radio virus came back.
I have a few post but my preference goes to the old (solid strong reliable), nothing to envy to what came from -_-
73's all
& 88 YL;)
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CB Radio Repair manuals and documentation / Re: Wanted, factory service manual for cobras
« Last post by st3ph on August 16, 2019, 06:14:54 PM »hi all,
i have see on all the internet i think...
nothing for my cb radio is a
Cobra 150-GTL
http://www.cbtricks.com/radios/cobra/150gtl/index.htm(nothing)
i have buy this but it's in UK channel, i have tested alignment is a PTM121D4X (cobra, ham internationnal, lafayette ect...)
i find more information, for alignment.
73's.
ty
i have see on all the internet i think...
nothing for my cb radio is a
Cobra 150-GTL
http://www.cbtricks.com/radios/cobra/150gtl/index.htm(nothing)
i have buy this but it's in UK channel, i have tested alignment is a PTM121D4X (cobra, ham internationnal, lafayette ect...)
i find more information, for alignment.
73's.
ty
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Amplifiers / Xforce
« Last post by Crambone on July 30, 2019, 03:31:08 PM »In need of a schematic for XT400