Changing the fluid… on your transmitter… P1

On most high power UHF, some VHF and some FM transmitters, the transmitter’s “residual transmission heat” is dissipated by liquid cooling systems.

Transmitter Liquid Cooling Plumbing for a Comark high power UHF transmitter.
Transmitter Liquid Cooling Plumbing for a Comark high power UHF transmitter.

Here in the US, it is very common to use a mixture of distilled water and Propylene Glycol (“Glycol”). The mixture varies based on the environment of the transmitter and the location of the external cooling systems (heat exchangers).

Transmitter heat exchangers mounted outside.
Transmitter heat exchangers mounted outside.

Glycol is used because it will prevent the outdoor systems from freezing. It also prevents the water from boiling when transferring heat. Glycol is a nasty substance if you have to handle it, with an invasive pink dye, which is very difficult to wash out when dried, and a perfume agent that is pungent at best. However Propylene Glycol is considered non toxic. (Unlike Ethylene Glycol, which is used in radiator fluid and plastics manufacturing.).  Glycol is a chemical that can leave behind residue, which over time, especially when mixing with water, can cause the pH balance and other properties of the glycol to change. This breakdown of the elements of the glycol, causing deposit buildups in both transmission components and the cooling system itself. It is important when using a piece of transmission gear, that this chemical be tested every other year, to determine if it needs to be changed out before that damage occurs.

We take the sample using the drain port on the IOT tube bottom.
This is done by running the fluid into a small bucket for about 15 seconds to flush out the crusted contaminants. Then using the sample container, we fill it slowly with the fluid.

Glycol sample collected underneath the IOT
Glycol sample collected underneath the IOT

The company we use, Dow Chemicals, provides the sample containers to put the samples in. They give you documentation and a little box to ship the samples out.  Because we have two discreet cooling systems, two samples of the chemical are sent.

Dowtherm SR-1 contained and ready to be sent for analysis
Dowtherm SR-1 contained from both systems and ready to be sent for analysis.

In a few weeks, we will get the results, and based on the results, will determine if we need to flush the entire cooling system and replace the Glycol in it.

Da Crane, Da Crane!

WGBH-FM (89.7 Boston) on Blue Hill in Milton is undergoing an antenna replacement. As part of the replacement, the top mast  is also being replaced with a new mast. This morning I caught this on the way into work, the crane is up working on the replacement.

(Sorry for the fuzzy picture. Smart phone picture!)

WGBH-FM crane setup to replace antenna and pole.
WGBH-FM crane setup to replace antenna and pole.

What lurks behind the walls…

We had an ongoing issue in the “satellite office” (bathroom) where the light would cycle, like we took a quick power hit. I always just attributed it to the ballast or the bulbs being funky, but today I decided to inspect the wall-switch, just to check. Sure enough, this is what I found. Those who know electrical theory know why this is extremely dangerous. The “electrician” who may have installed this switch, never pre-twisted the wires before the wirenut, and never twisted the wirenut tight. So the neutrals both became loose and over time arced to the point of creating oxidation on the wires.

Needless to say, the switch has been replaced and the wiring is all cleaned up now.  You never know what lurks behind the walls sometimes…

Well cooked neutrals.


After waiting for the floor buffers to finish drying, I was hanging outside , watching these ominous clouds go by outside.

Storm Clouds at the transmitter in Needham.
Storm Clouds at the transmitter in Needham.


It’s the return of the NECRAT-QUIZ

Update. This WILL be the LAST NECRAT Quiz, seeing how little response I’ve received.

I have decided to bring back a classic!! It’s the NECRAT QUIZ!!
While there aren’t any prizes yet, there could be down the road…

So with that……

Can you identify this transmitter site?

QUIZ Aug 2014

You can guess by registering here, or by using the Facebook page. Hints will be given before the end of the month!  Good luck!!


Welcome to the NEW NECRAT

Welcome to the new style of NECRAT. I call it NECRAT version 5.0!

This brings NECRAT into the 21st century with a fresh look, more detailed updates, and an exciting way to keep this site on the top of your frequently visited list! The new format will allow me to go into greater detail the changes I made here, and the updates. It will also allow me to start some new features that will make you want to come back to the site often. While there was a lot on the original site, this will just add to it. Don’t worry, the very hefty indexes of pictures and descriptions remains free to view (in fact the whole site is free, still!!). Just go to The NECRAT Wiki to see all the content you known and love here on NECRAT. I hope you enjoy these changes i’ve made, as I have put a lot of hard work and effort into this upgrade for you my fans!!

Mike Fitzpatrick
NECRAT founder and owner.

P.S.! feel free to sign up for an account to add your comments to the site. If you sign up but don’t receive the email activation , just email me and I will square it away! – Mike

Update from the week of August 4th 2014

A nice week away from a very busy work schedule allowed to meet up with some old friends and add some really nice stations to the site… I started out by stopping at the tree- er- cell tower (it’s easy to see how I could get those confused, eh?) of WYQQ Charlton, and in Westfield to see WSKB’s new antenna/tower.

WYQQ Charlton Aug 2014

Then it was off to South West Vermont to get some updated pictures of the new 93.5 translator in Brattleboro and to Mt. Equinox to see the work done up there as well.

WEQX Manchester, Mt Equinox
WEQX Manchester Aug 2014

Before I was off to see and update my main goal for the week, Hartford, I had to stop by and not only see but help my friend Pete Partenio work on the WSBS transmitter.

Peter Partenio - WSBS
Pete Partenio working on a PA board from WSBS’s Harris SX2.5A

Then it was off to Connecticut, with a stop by a couple of non comm stations and WPOP, before heading to WIHS 104.9, and a chance to see their new transmitter with Willie Barnett and G.J. Girard.

WIHS Transmitter
WIHS’s new Harris FAX 3.5K transmitter – Aug 2014
WIHS with Willie Barnett
WIHS’s engineer Willie Barnett – Aug 2014

And then up to West Peak with my friend Gene Faltus to see the transmitter of WZMX! (And update my 7 year old West Peak pictures!)

WZMX Transmitters
WZMX’s primary and aux transmitters – Aug 2014

The tour then allowed me to update my pictures of WLAT 910 minus the one tower, and to add MarcB’s most favorite radio station, WNTY!! er.. WXCT!!  Along with the towers of WTIC-TV and WVIT!

WLAT New Britain
WLAT 910 minus 1 tower – Aug 2014
WXCT Southington
WXCT Southington

And of course , no Western Mass vacation would be complete without the addition of a couple Stewart’s Shops. Including this beautiful one in Manchester, VT!

Stewart's Shops - Manchester
Stewart’s unique shop in Manchester

Come check it all out now at NECRAT.US!

A Broadcast Engineering Website