Notes on AL-1200 (5)

Bought 7 February 2013. Notes from W8WTS:

Here is the story on this AL-1200 amp. W8RZ purchased it new in 2001. Dan does not have a station of his own, so after purchase we took it to W8EDU where it was used for ARRL SS CW from W8EDU for 2001 through 2012. That was the only use that it ever had, i.e., about 300 total hours. When not in use, we put it back in the box and back on the shelf. I know that that it will make > 1500 watts with normal transceiver drive. It is completely clean and in the box with original foam packing inserts. The only cosmetic defect is that the black cabinet paint is bubbled on the tube air outlet. That happened c. 2007 when Windows decided to do an update and reboot, keying the amp into the wrong antenna at 4 a.m. In spite of the over-heat, the tube did not lose a watt of output and continues to work like new. Right now, the power transformer is wired for 208 VAC primary, the voltage available at the W8EDU shack. The tap will need to be changed for Signal Point 220 VAC.

K8ND will arrange to pick up the amp.

Bought February 2013 and picked up by W8WTS on April 6, 2013 from the Case Western-Reserve University club through Dan, W8RZ.

SN 12354

26 May 2013

Picked up by W0CG at W8WTS' home in Shaker Heights.

30 May 2013

Transformer and tube removed and prepped for shipment to Curacao as ocean freight.

9 June 2013

Transported by W0CG to W8AV's barn for ocean shipment. RF deck in CCC white hard case. Transformer in a boxed cooler. Tube and chimney in double-boxed packing.

16 September 2013

Placed in service for testing at Station 4. Amp immediately began smelling hot and the thermometer at the air outlet rapidly went up to 200 degrees, where 120 F is the normal air outlet temp. W9NJY swapped in Tube 36 and all operation of the amp is now normal.

24 October 2013

K8LEE replaced the T/R relay before CQWW SSB 2013.

18 October 2014

Placed in service at Station 4.

31 March 2015

Placed in service at Station 1 after a time in storage. Working perfectly.

5 April 2015

T/R relay sticks at times and needs to be keyed repeatedly to get it to "make".

29 November 2015

Popping sound from power supply. W9NJY and N7IR and I opened it up and saw nothing obvious. Will try installing new AL-1200 HV supply later this week.

2 December 2015

W9NJY installed entirely new HV supply assembly (diodes, resistors, electrolytics) from the storage duct Box 9 and popping is cured. Old supply board was stowed in Box 9 with a note of explanation in the bag. Electrolytics are Cornell Dubilier DCMC271T450AA2B  270 ufd 450 VDC, quantity 8.

14 February 2016

Amp was removed from service by K8ND after both he and W8WTS and SM4KYN reported it was hanging in TX and it took repeated presses of the foot switch to get it to go back to RX. This date W0CG installed a new T/R board from bench stock, Job took four hours and involved very tricky surgery to replace. Amp is now back in service and appears to be operating normally in test at Station 1. Board was Ameritron PN 861-0453, Rev 3.

22 February 2016

K8ND ordered four more T/R boards, only $5 each. This amp performed perfectly at the 40 meter station in ARRL DX CW 2016.

9 March 2016

K8ND ordered two T/R boards this date from Ameritron based on the invoice from a couple of years ago. $31 each.

20 February 2018

Removed from service at Station 1 after CQWW CW 2017 and ARRL DX 2018. Working fine except feels a bit hot in normal operation at back right of RF deck.

16 February 2021

This was at Station 1 after returning from the COVID year. W0CG cleaned and dusted inside. At turn-on the relay click did not happen and in less than a second R3, the step start resistor burst into full flame. N1ZZ will bring parts including the resistor and a new relay on 28 February..

3 March 2021

After days of troubleshooting AF4A and N1ZZ deduced that the tube was bad, seeing flashing in the bottom of the tube. With the tube removed all startup is normal. Also fixed a broken connection on one of the HV equalizing resistors. Discarded Tube 36 and installed Tube 39 this date. Seasoning filaments.

18 March 2021

Placed in service at Station 2.