[R-390] Re: R390A Education

[Flowertime01 at wmconnect.com]

Bill,

I was taught in a class at Fort Devens Mass back in 1969. The class was 
presented once every two weeks. As most classes were only one week there were Two 
R390 class rooms. You did a week in one and then a week in the other.

The instructor was a world war two vet. He was teaching the class because the 
army types though the class was too hard to teach and was not doing a good 
job of teaching it. I lucked out and had a real pro for an instructor. Students 
were doing to school eight hours a day back then in one shift. By 1972 classes 
were six hours a day and taught in two shifts from 6 AM to noon and Noon to 6 
PM. I taught the afternoon shift then. 

R390 was a two-week class. Monday was a short history of the receiver R390 
and R390/A a tour of the shop and a look at the receiver. A look at the test 
equipment. A look at the TM. One hour wasted and most of two weeks to go.

Pop open your R390/A TM flip to the first schematic of the RF section and 
power supply. Finish the day doing schematic analysis of that single sheet of 
paper. Sweep the classroom and make it to formation to march back to Connies for 
supper.

Day two pop open your R390/A TM flip to the second schematic of the IF 
section. Students shall do the schematic analysis of that single sheet of paper. 
This was a guided tour and you were expected to be able to read schematics and 
determine what was happening in that circuit.

Day three morning was look at your receiver. Open your eyes. The after noon 
was listen to your receiver. It was that day that I learned all the stuff I 
posted last year.

As part of the trouble shooting experience we were lead through the receiver 
step by step knob by knob. Each student was standing in front of a receiver on 
the bench with eyes open. Headsets on and looking into our own receiver. The 
instructor was walking up and down the isle calling out education. Set 
function knob to MGC. It's that knob son. Set limiter switch off. Spin the dial to 
7+000 look at those cams. See this. Move the MC Knob to 8 see that switch move.

Set that receiver up on end. Set the bandwidth to sharp. Hear the difference 
in sound. Pull RT510; hear the difference in sound. Lift the rack and move the 
slugs. Hear the loss of cal tone.

On and on and On for 8 hours. This is how you front panel a receiver to 
localize a problem down to a stage.

On day four we did an alignment procedure. One student one receiver one day. 
Step by step under verbal instruction. See what is going on listen to that. 
See the meter move. At the end of the day we all listened to every receiver and 
agreed that every receiver was working. From then on the mantra was yesterday 
it worked. Today it does not work. There is only one thing wrong with it. Can 
you see it? Can you hear it? You can find it and you can fix it.

Then for 5 more class days it was find the bug and do it again Sam. There 
were 10 receivers in the room. We had eight students in my class as we had lost 
some. Eight of 20 made the eight week cut. We eight were lumped into one class. 
Most classes were eight nine or ten students. You did not loose 6 of 10 every 
week. Two weeks in a row was news making and investigated. The instructors 
loved us. They had had the last week off due to no students.

The ten receivers each had a different problem (bug) placed into it. You had 
8 hours to do ten problems in ten different receivers. You did round robin 
time between time on a bench, talking to an instructor at the black board or out 
in the hall smoking. In 5 days you did 50 problems in a R390/A. you walked up 
to an R390 on the bench. Eyeballed and listened to it until you isolated the 
problem. You did this in less than 15 minutes. At an hour you failed to get it.

You practiced the look and listen approach to isolate problems. It was learn 
this receiver from the look and feel and sound.

The last day was 5 bugs in 8 hours for a test. The same bug was in two 
different receivers so you only had to visit 5 receivers.

Other equipment classes were five days each. My AN/THN-11 Recorder class as 
five days. Monday was introduction, play with the recorders, theory of how 
recording and magnetic tape works and a 10-question quiz. Tuesday was schematic 
analysis and operational analysis. Wednesday, Thursday was 10 bugs each day. 
Friday was a troubleshooting test. Five bug in 6 hours. You had a tube, a relay, 
a power supply, a bad filter cap with hum, and a capstan motor speed loop 
problem. 

The R390 had an extra of schematic analysis a full day of look, listen and 
operate, a day of alignment and two extra days of bugs.

Just one day it was look and listen. In the R390/A you can pull tubes one at 
a time. In the R390 the tubes are in filament strings. So a pulled tube would 
drop two or more tubes in the filament string. BFO on and off. VFO you can 
unplug the connector. We set those receivers up on end, got out the tube pullers 
and when at it. Under supervision from a master you pulled one tube at a time. 
The day after we pulled and replaced every thing in the receiver we realigned 
it. 

Set your receiver up on end. Get the schematic out and start at the audio 
output. Put your headphones on and pull a tube at a time. Listen to the 
difference. Play with the knobs to understand how it sounds from that stage to the 
output. You can teach yourself this stuff about your receiver in a couple hours. 
You spend more time burning fingers and waitings for the filaments to warm back 
up than you do learning what you need to know.

Yea so like one day this old guy said this is how you trouble shoot that 
receiver from the front panel knowing what you do from the schematic analysis and 
theory of operation you can look and listen to the tube stage. Then you can 
align it with some wire, a meter, generator, spline wrench and pop icicle stick. 
He spent 8 hours leading us through it all as part of the trouble shooting 
process.

I agree it is not all in a text file I have read. Guys who knew the equipment 
taught it. It was taught as part of getting an understanding of how things 
work. It is still taught in military schools every day to lots of students. The 
process is used on every thing from a butter knife in the mess hall to 
aircraft engines. Military guys who were trained to maintain some item of equipment 
went through the process while being taught to perform maintenance on the item 
under instruction. For some an Ah HA come along and they went you could apply 
this to any thing. Some other struggled through the class and could not wait 
to get out of service. 

In my service time I did few soldering iron repairs. We were maintaining 
receivers at optimum performance. I spent more time soldering inmy 10 TNH-11 than 
anywhere. We unsoldered everything at least once just to see what would 
happen. Some guy would ask a question. We ask what do you think the outcome would be 
from the schematic analysis. The we would try it just to see what really 
happened. I spent a lot of time cleaning up solder joints in the recorders. They 
were the same ones I had learned on back in 1969. every joint on a circuit card 
was clean and neet. You did not eyeball your way through my bugs. We had meg 
ohm resistors with repainted color bands. We had real tubes that had failed. 
we had relays that we had fried inside and had never been soldered open. For 
bad fuses we used only ceramic fuses you couls not eyeball. You had to pick up 
the meter leads and test. 

In the Field (Nam, Korea, Okinawa) I tested tubes and did alignments every 
day. For monthly PM we would walk out to a receiver and do an eyeball for blue 
tubes and run that knobology. You found loose knobs that way. You did listen 
for a cal tone on every MHz and at every 100 KHz across one MHz. You did a 
listen at WWV or the Japan equal. If a receiver was having a problem your operators 
did a trouble call on it. You did dial light replacement in the rack as they 
were called in on trouble reports. I know I fixed at least one of every thing 
over time, but I would do days of PM on bunches of equipment that was just 
meter, meter, meter. That's a Korean expression for Look, look ,look. To meter in 
Korean was to look at a girl. To be caught meter, metering was to be caught 
looking at another girl. We were in the preventive maintenance game not the 
corrective maintenance game. That why it is called PM not CM. Like Preventive 
Maintenance. So the goal was to get there before it failed. Thus we did not have 
a lot of charred things to replace because we let a tube go to complete 
failure. They fail did and I did do a lot of soldering.

So every day the maintenance men did this spin the knob test on receivers and 
knew what they were trying to establish as good or not good in a receiver. 
Think of doing the front panel knobology and trying to determine if we were 
hearing a microphonic tube in a receiver. Spin the knob on a receiver, go get a 
tube and plug it in, Ask the operator if that sounded better or not. Receivers 
were in racks. You could not reach inside and be tapping tubes. You had to 
front panel it and get down to one or two 5749's in the IF and swap them one at a 
time to find a micrphonic tube you could hear by playing with the knobs. 
Switch the band switch and hear an IF tube pop and ring microphonic. Roll from 7 to 
8 to 7 and tell if the first mixer was sounding weak, noisy, and microphonic. 
You did not learn this in a day at school. I had several repairmen we would 
not let work on an R390 in the shop. Other guys got good over time.

I had a Teletype mech. in Okinawa names Randy Smith. He carried a 3-foot long 
screwdriver in his belt like a sword. He could walk up to any model 28 
Teletype and fix it flat right now. Those were / are mechanical beast. They would 
vibrate screws loose. Randy could feel one across the room and know what it 
needed. He could set mechanical setting by eye that others needed their go no go 
gauges to set. Some where some guys just get it and the rest of us just have to 
keep working at it.

I had a 33C who had a degree in Math. He did his four years and when back to 
the classroom to teach. I have meet ASA guys over the years. Most did their 
service time and never looked back. Most O5H's would never consider being a ham 
and do CW.

Roger AI4NI