Re: {Collins} spam Re: Collins 516F2 power supply

The w0iy kit is very well engineered and works well. If you want to solid state it is a great way to go.

Scott Kerr - KE1RR
President - Collins Collectors Association
Editor - Signal Magazone
-----Original Message-----
From: Collins [] On Behalf Of Jim Jones
Sent: Thursday, September 08, 2016 8:05 AM
To: 'Bill Cotter' <n4lg@xxxxxx>; 'Joe W2KJ' <w2kj@xxxxxxxxxxxxx>; collins@xxxxxxxxxxxxx
Subject: spam Re: {Collins} Collins 516F2 power supply

Let's not forget that the Budster mod'd at least 500 516F-2 supplies that included replacing the rectifier tubes.  At least a hundred others followed his lead.  Now Barry and Rod are supplying the w0iy kit that allows users to continue the use of solid state devices.  

Using the freed up filament winding to buck the input voltage results in outputs closer to the originally specified levels.  

I have always thought that 5R4s and 5U4s were potentially lethal to systems when they arced over.  No way to predict when arcing will occur and one hopes that the fuses will blow to reduce damage.  

On the other hand:  the Collins 233D that we are restoring for the Rockwell Collins Museum in Cedar Rapids uses 6 ea 872A MV tubes in a doubler circuit to supply 4200 VDC to the plates in the final.  I was warned that MV tubes were noisy, environmentally bad and could explode.  Problem is that those 6 tubes are behind a window in the power supply bay and when you bring the HV up, the blue glow from the tubes are a lightshow worth watching.  
We found a snippet from a Warren Bruene speech that mentioned his fascination with watching the MV tube glow when a similar transmitter (231D I think) was modulated.  

We spent quite a lot time making sure the 872s were properly conditioned before we brought up the high voltage.  We pulled the rectifier chassis and put it behind a think plexi shield and borrowed a 400 pound 3 ph Variac from one of the engineering labs to bring up the voltage to the chassis from the
600 pound plate transformer.  After the tubes were warmed, we would slowly increase the input until we got arc over on one of the tubes.  When the arc over occurred, there was a scary kerchunk from the plate transformer.  Of 6 original tubes, we had to replace 3 because the old tubes would not get to full output without arcing over.  

The 233D has a 30 second time delay after filament voltage is applied to prevent bringing up high voltage before the tubes are warmed.  That doesn't appear to be nearly enough, so we use a laser thermometer to check the tubes to make sure they are ready for the high voltage.  Otherwise, there is a bright flash and a loud kerchunk and the overload circuit shuts the high voltage down.  

The 233D is located in the old Comm Central equipment room at Building 120.
Beside it in the room is the Byrd Expedition 20B that used 872s (non-As) for rectifiers.  One of the reasons I decided to keep the 872s in the 233D.

A previous owner replaced the 5U4s in the low voltage supply, but we left 3B28s in the LV supply 660 volt supply and the bias chassis 880 volt circuit.  

Please don't ask about how or when we are going get the 3KW Autotune 233D on the air.  We still need a 9 dB pad to reduce the output down to the legal limit.

Jim w0nkn

-----Original Message-----
From: Collins []
On Behalf Of Bill Cotter
Sent: Thursday, September 08, 2016 6:54 AM
To: Joe W2KJ <w2kj@bellsout're .net>; collins@xxxxxxxxxxxxx
Subject: Re: {Collins} Collins 516F2 power supply


I have installed and used two of the W0IY conversion kits in my
516F-2 power supplies for the KWM-2A and 32S-3. The design by the former Collins engineers is well thought out, and the quality is nothing short of what Collins would have expected. The kits also address the downside issues of solid-stating a 516F-2 that have been presented by this group.

Both of my conversions are setup to use the rectifier filament windings as "bucking" in the transformer primary, and the HV/LV/filament voltages are right on specification with the AC line voltage at 115VAC. The best part is the power supplies runs absolutely cold.

73 Bill N4LG

At 11:21 PM 9/6/2016, Warren Dean wrote:
>W0IY's conversion kit works very well. $85 or do for the complete kit 
>with all components and PCB.
>On Tue, Sep 6, 2016 at 8:19 PM -0700, "Joe W2KJ" 
><w2kj@xxxxxxxxxxxxx<mailto:w2kj@xxxxxxxxxxxxx>> wrote:
>Howdy Gang:
>Been reading recently about solid-stating the 516F2 power supply 
>including replacing the selenium rectifier in the bias circuit a diode.
>Assume that some electrolytics should also be replaced given the age of 
>the unit.
>Seems like a good thing to do...I did the power supply rebuild on my 
>Drake AC4 supply and all is fine.
>Opinions/suggestions are most welcomed to this Collins newbie.
>many thanks for any info.
>                         73, Joe W2KJ
>                         75S3B/32S3/516F2

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