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| Warning: I am not trying to tell anyone that I am an expert, I really have
little knowledge
about the radio’s internal circuits, other than what
I can learn from reading the
book and schematics.
I first saw one of these marvels when I went to a MARS
convention in
St Louis MO, in the early 60’s. The Collins Rep had a wire out a
window and was dialing in frequencies and talking with Collins. This freq, then
that freq, then another, it was like magic WOW what a
radio. I never thought much about getting one
of these
on the air,
until my friend Math
ON8PO convinced me I should do it. I was lucky, he gave me the Test Box (gray unit) and a control head, and the male plug that would interface to the test box. There are 3 versions of this radio, none of them are very user friendly as far as the power requirements! I got my radio on Ebay, I paid too much, but I didn't want to buy a junker. The radio I got worked reasonable good. It does have a few bugs, like a whistling sound that creeps into the receive audio ?? and it did work on AM but for some reason it doesn't now, I will eventually fix these problems, but just happy to get the radio on the air. What you need: A big 28Vdc power supply and a 115Vac 400 Hz supply. The proper control box. You can use the interconnect diagram (listed to the right) and make a wiring harness. Rather than using the Test Box (TS-1949A/URM-157), if I had it to do again I would just make a 19" panel with the control head and whatever controls / jacks I needed. The test box is for all three 618T's , so I pushed the controls that select the radio types into the box, so I can't accidentally turn them. I've heard that selecting the wrong radio might cause smoke ?? ! |
Here are the
Schematic's and a great interconnect diagram! Provided by Loek d'Hont AC5XP
618T-3_interconnect_with_180L-3.pdf |
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400 cycle power supply 426T-1 |
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From what I know the T3 is the only radio
that is easily to get the proper power
to operate, mostly its brute force
28VDC and a small amount of 115V/400cycle
power. The 400 cycle power is a
problem, but nothing that can’t be overcome.
Be
careful what you buy, I thought the 516H-1 would make 400 cycles.. Not so. I was
looking at some rotary (dynamotor type) supplies on Ebay, but I found something
much better, a Collins 426T-1 converter at Murphy’s in San Diego, for $125. It runs
on 28V and produces the 400 cycles, in fact, way more than is required by the radio.
I got lucky again, I had this giant oversize power supply I bought at a surplus auction, its
unregulated, but beefy enough that even under key down AM the voltage, although
being
a little low is still in an acceptable range.
Getting the plug that goes into the Radio?
I might have been able to purchase the female plug, as seen on the back of this rack, but
I wanted to sit the
radio in a rack, so I purchased a brand new retro-fit rack 49-T4. This
retrofit trick is used so the
aircraft Weight and Balance doesn't need to be recomputed, and so the old
aircraft wiring works.
This saves the aircraft owner a lot of money. I am going to buy some shock
mounts to attach to the
bottom of this rack. (not done yet) note: the radio must be elevated , as
forced air escapes from
the bottom of the radio.
Control Head, be sure to read the link listed above "618T sales" you can learn a lot about the correct parts and pieces.
I really haven't said much of anything useful here, but if you want to talk
about my problems, experience call me or
email , go to my home page for my contact info
HOME
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IF you have useful information about coming up with 400 Hz power, or other
information you think should be added to this page, anything ,
everything.....
please email me the info, I will attempt to incorporate it .
maybe we can help someone else get their 618T on the air
. thanks k0ip((at))ida.net
Here's a list (short as it is) of people that NIGHT be of help if your having
trouble.
first, ME.
then possibles
James at xpjames((at))xpondr.com
Paul at wb4wcjp((at))aol.com
Lou at critech2((at))earthlink.net
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