Arctic Diamonds - TF4M » The Shack

Otradalur Panorama photos

TF4M — Wed, 25 Jan 2012 14:39:02 +0000

These are the Panorama photos I used to make the Virtual Tour.

Virtual Tour of TF4M

TF4M — Wed, 18 Jan 2012 18:28:10 +0000

Array Solutions QSK-MASTER

TF4M — Fri, 12 Aug 2011 14:43:12 +0000

The Array Solutions QSK-Master has now been installed with the Harris RF-110A amplifier and it works beautifully.

The RF-110A had slow T/R switching making it almost unusable for my purposes.

With the QSK-Master, the T/R switching is better than anything I have ever experienced before and with the small modification I performed to control the bias directly from the unit ( a 10V control voltage at 4 mA is switched to control the bias of both driver tubes and output tubes ), the amplifier is now biased to cutoff when it is not keyed.

This ensures much less heat and less waste of power.

The amplifier is even cut off between CW characters in QSK operation.

TFM 3928 DxO

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TF2SUT visit

TF4M — Tue, 02 Aug 2011 16:42:23 +0000

Samúel, TF2SUT visited my station and was given a quick tour of the facilities with YL Andrea.

YL Andrea and Samúel, TF2SUT

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Tower of Power

TF4M — Mon, 18 Jul 2011 18:16:21 +0000

The new Harris RF-110A Radio Frequency Amplifier has been installed and tested.

The amplifier has 2 x 4CX1500B tubes in parallel in the output stage (3000W plate dissipation) biased for Class AB1 operation and runs an easy 1 kW output in any mode (key down forever…) on all bands.

It takes 100 W from the exciter through a 30dB attenuator which provides 100mW to a pair of 8122 tubes running in Class A (capable of around 1kW by themselves) which amplify the 100mW signal to 10W to drive the PA tubes.

The amplifier is cooled with a very noisy 4″ muffin fan rotating at 11,000 RPM – a real screamer – necessitating installation in the adjacent soundproofed equipment room.

The T/R switching is rather slow and clunky by today´s standards – on the order of 200mS until full output is reached due to timing constants in the bias circuit which prevents hot switching of the relays, but by increasing PTT to generated RF delays in the equipment everything functions reasonably smoothly.

An ArraySolutions QSK Master unit is on order to use with the amplifier – once this unit is installed there will be no moving parts inside the amplifier.

The RF-110A generates 3.5kW of heat for 1kW of RF output – this makes it necessary to improve ventilation of the equipment room. It consumes 1kW in Standby mode.

I would appreciate comments on the quality of my signals as I test the unit.

From top to bottom: Harris AM-7224 1kW amplifer, Harris RF-110A 1kW amplifier

Harris AM-7224 1kW amplifer and two power supplies for the AM-7224 amplifiers.

In addition the station has a Harris AM-7223 500W amplifer, an Emtron DX-2SP and an Emtron DX-3 amplifier.

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