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28-V, High Current Power Supply - Adjustable? Apr 20th, 13:35 2 267 on 21/4/14
G5RV Configuration Question Dec 20th 2013, 23:22 3 414 on 21/12/13

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Topic Author Posted On
28-V, High Current Power Supply - Adjustable? Steffen on 20/4/14
I am referring to the project on page 17.36 of the 2014 ARRL Handbook. It is just what I need but for one feature. I need the output voltage to be variable between approximately 5.0V and 24.0V. My question is: Is it possible to make the supply adjustable over that range by changing the values of R8, R9 and R10? I want to build a supply that can output between 5.0V-24.0V at 10A.

I am seeing that it is not easy to find the transformer listed in the project description. Therefore, I would like to substitute it with a Hammond 28V 6.25A (CT @ 14V at 12.5A) . I realize that the supply current rating will drop from 15A to 6A, but that is fine for my needs. Yes, I would like to have a supply that covers the voltage and current requirements of the newer linear amps as well, but it does not seem possible due to the availability of the Avatar transformer.

Thank you,

Steffen (KA2KNX)
G5RV Configuration Question Steffen on 21/12/13
Thank you for a very complete answer. I will work on this and report back. Once again - just what I needed to know!
G5RV Configuration Question Steffen on 20/12/13
I live in an apartment building and want to put a G5RV on the roof. I have to keep the entire structure out of view from the street, and also avoid running coax on the roof surface. These restrictions necessitate my taking a bit of liberty in the placement of the G5RV.

The roof is about 60ft above ground. I do not intend to invert the G5RV, but rather support both ends by stringing them up to two convenient tie points on the roof. My main question concerns the 31ft 450 ohm ladder line matching section. I read that the ladder line should come away from the flat-top at a right angle for at least 15ft. Can I run the ladder line down the side of the apartment building brick wall and near a fire escape, or will the brick wall negatively effect the intended properties of the line? Furthermore, can the antenna be about only 5ft off the surface of the roof and still give good performance?

Thank you - KA2KNX

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