During the early seventies, I was working for a 2-way radio shop
in the Los Angeles area.
One very hot summer day, one of our customers complained his base
station had apparently quit so I was dispatched to repair it. The
base was in a unventilated two car garage on a hill top.
After I had arrived at the site, I opened the garage door and
could barely stand the heat inside. A couple of minutes later, I
went to the customers base station cabinet and felt the cabinet
temperature - almost burned my hand.
Those days, there were many systems that were still vacuum tube ...
including this one. The crystals were installed in 85 degree
centigrade ovens to stabilize the temperature.
The service monitor showed the transmit and receive frequencies were
low by 4 or 5 kHz - meaning the crystals were too hot.
At that point in my career, my fingers were used to sensing crystal
oven temperature so I reached for the separate ovens to see if they
had overheated - they hadn't.
I left the cabinet door open for a half hour or more to allow the
radio and cabinet to cool off. Then I measured the frequencies
again ... had drifted back on frequency so I closed up the
equipment, the garage and departed.
The point here is the radio and cabinetry had been hotter than the
85 degree centigrade crystal ovens (185 degree F) and had began to
control the crystal temperature and thereby the frequency.
Since we didn't control the garage, we left it to the customer to
contact the site owner.
For you Motorola types:
The tube equipment involved was most likely a C53GKB-3100A Station
The receiver was a Series Sensicon 'G' receiver because it had the
Private Line circuitry on it.
There were three versions of the 60 watt 5" wide transmitter chassis:
The Series 'A' - used an 829B final tube;
The little used Series 'J' - used a pair of 6146's as the
final tubes;
The Series 'K' - used an 5894 final tube.
In this installation, it was most likely the series 'K' transmitter
strip as it also had the Private Line circuitry on it.
For you General Electric types, the competition radio to the
Motorola C53GKB Series was the Progress Line Station.
(Yes, I used to service them too.)
-------
My experience with incandescent light bulbs is if you really need
long life, place two in series ... or as I did one time, a silicon
diode in series with one lamp.
Early in the 1980's, a friends housing rental came up empty and he
contacted me to go in, clean and make it ready for the next renter.
Inside, I found a used RC Cola lighted sign / clock.
One of the two 25 watt light bulbs was burned out. I took it home,
cleaned it up, wired the two light sockets in series and installed a
pair of 40 watt bulbs. Then I hung that sign / clock in my bathroom
as a night light.
Late 1998, I sold my place and relocated to another part of the
state. Those two 40 watt lightbulbs were still in service ... but
the clock motor was so noisy, you could hear it a couple of rooms
away.
73, (NOT 73's)
Neil McKie - WA6KLA
Joe wrote:
>
> Cooling: This can normally be done with lots of moving
> air, Air Conditioning is not always necessary. You
> could use 2 fans, one small one thermostatically
> controlled to cool the cabinet to maybe 75 degrees. I
> would have a second larger fan to take care of the
> really hot times, maybe set at 80 degrees. This would
> give you redundancy in cooling. I worked for several
> paging companies in the past and some of the sites
> were 120 degrees or more in the summer. As long as
> the fans kept working, the equipment did not fail.
> The most important thing when moving air is to make
> sure that you use filters and clean them often. The
> openings also need to be made rodent proof or you will
> have a mess.
>
> Heating: I use a 40 watt light bulb in my repeater
> for heat. I have it plugged into a "Freeze Alarm"
> unit and set it to 55 degrees. The Freeze Alarm is
> something used up in the North that you normally plug
> a light into and put the light in your front window.
> If your heat goes off while you are away in Florida
> for the winter, it will alert your neighbor that there
> is a problem with your heating system. This works
> well and I probably will put two of these in my
> repeater this year. Last year, the light bulb burnt
> out a couple of times, probably from being turned on
> and off so many times.
>
> 73, Joe, K1ike
>
> --- Robin Staebler <[EMAIL PROTECTED]> wrote
> > I am thinking about security and ventilation.
> > Site is cool/warm (comm trailer on state/county site
> > heated/cooled)
>
>
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