[R-390] RF deck alignment

[Flowertime01 at wmconnect.com]

Roger, can you go through the Second IF alignment steps again. Does this 
apply to both the R-390 and the R-390A?? I have had similar problems doing that 
alignment on a R-390A.
-73- Peter K2LRC

Can you expand a bit on the "octave" tuning method you described?
Thanks again, Barry - N4BUQ
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The RF deck has six bands of tuning. There is band width in the IF and there 
are first and second mixers in the RF deck. 


0.500    - 0.999 First octave
1.000    - 1.999 Secons octave
2.000    - 3.999
4.000    - 7.999
8.000  - 15.999
16.000 - 31.999 sixth octave

To give us Fellows a way of talking about a rack of RF as opposed to a single 
megahertz of RF from an oscillator set up and megacycle change knob we talk 
about one of these six slug racks being an Octave Look at the harmonic 
arrangement of the RF slug racks and you see where this reference come from. The 
octaves change with the RF band switch. The crystals change with the Megahertz 
Change knob on every detent megahertz.

So when we talk about tuning an octave we are working on one of these RF slug 
racks, its three transformers and its four trimmer caps. Of course you need 
to drive the antenna input with a balanced source to get observe any change 
with the first trim cap in the first can of each octave. The R390 TM says use two 
68 ohm resistors (this works) to drive a balanced input into the receiver 
from a single coax signal generator. The R390/A TM missed the whole section One 
signal into two resistors and one resistor each into each antenna input.

The first and second IF cams also move with the Kilohertz change knob. And 
yes the 1.000 to 1.999 and the second IF tracks with this octave.

The second IF tracks one megahertz     2.0 - 2.9 gets mixed with 2.455 - 
3.455   and puts out 455.   

The receiver kicks 1.000 - 1.999 up to 17.000 - 17.999  megs and back down to 
2.0 - 2.999   The slug tuned VFO mixes the 2.0 - 2.9 out to 455.

So when you need to do two of these receivers every shift, have some screw 
off time, handle the pop up trouble calls and get a mid shift meal in, you learn 
to geterdone.

A real semi (once every six months) can be done in 4 hours. If you ain't 
getting it on hard for a good hour hours you did not do a full semi.  

So you learn from them that been there done that just how best to geterdone.

Park that signal generator into the IF input and get the IF deck up to 
specification.

Park that signal generator into the RF balanced antenna input and get that 
deck up to specification.

A bath to wash the face. A blow job and oil in the gear train. Check the 
mechanical dial over run and cam adjustments. Check all the tubes in the TV7. Set 
up the IF deck and trim the BFO and  Gain Adjust. Check the IF signal to 
noise. Set up the RF deck. Neutralize the BF. Check the VLF end points Do a 
alignment on the RF deck. Put the RF deck cover back on and return the receiver to 
the rack where you removed it from at the start of the shift. The time you spent 
walking the floor to find the receiver does not count. Sounds easy. Geterdone 
and go to mid shift meal. and do it again before you get relived at the end 
of trick. We would take two receivers on a cart and go find the tow that were 
due for PM. At the end of shift you took them both back out on the cart and 
returned them to the rack. 

Macho man was to boost one on your shoulder and walk the floor with it until 
you found the one you were looking for. 

Think about a big room like 1500 square feet. A double wide rack with two 
receivers side by side and 15 of these double wide racks in a room. Think 32 
receivers in a room. Think 10 or more rooms. Think about 4 receivers in two side 
by side racks
with 2 prints in half high racks beside that and a 1/2 rack as a desk with a 
typewriter. Lots of floor space to walk around on. There was lots of other 
equipment like the RTTY demodulators and tape recorders and antenna couplers and 
rack fans.

Once you couple the signal generator to the RF deck you spin the knobs, tweak 
the caps, adjust the slugs and read the meters. One audio power meter and one 
DC volt meter on the diode load. 

The thing to do was drive all the signals through the 455 KHz 0.1 filter. On 
any given band the crystal could be off one-way or the other. the VFO may not 
be spot on or linear. Remember to open the IF back up to 2K when you look at 
the meters. 

Run the receiver over to the alignment point. Run the generator over to get 
an output. Start adjusting the signal level and rocking it into the band pass. 
Switch over to 0.1 on the IF and rock the generator into the best peak point 
you could get. Open the IF up to 2K and set the generator for a mid meter 
reading. Adjust what ever you were supposed to adjust at that point for best peak. 
Set the generator level and take a meter reading. Modulation off and 
modulation on. You had 20 and moved on or you went to work swapping tubes. If you 
swapped a whole set of tubes in that you knew were good and you were not close you 
had to stop and think.

So to make life easy the 1.100 and 1.900 adjustments were just made inline as 
you did the 1.000 - 1.999 octave you are set up for this. you get the slugs 
in Z216 at 1.900 and the caps in Z216 at 1.100

The second IF 1.250 and 7.250  We some days worked over to 1.250 if 1.100 was 
close to not passing and we needed a better answer. We did Z213 caps at 7.600.
Again if that was not peaking and passing real good we would dial over and 
set up for 7.250.

We always run the signal generator into the antenna input at the receiver 
dial frequency and peaked into the 455 crystal as best as we could hit it. This 
got us as good as a result as injecting into the test points. Some times we got 
better results than injecting into the test points.

There have been some good comments the last few days on the slugs and 
trimmers peaking. I can believe that some decks are in need of some small cap 
adjustments.

Slugs have aged. coils have aged. We are not going to get need stock so we 
have to change or add some small caps to bring some old circuits back to peak on 
frequency. 

Briefly (do not ponder this next idea to ill health) think about all those 
decks I dumped into the TTY degreaser as a cleaning method. I was expecting to 
get new transistor Racal receivers any day to replace those old R390/A s. I was 
trained on the new Racal receivers in school in 1969 and still waiting for 
them to show up at the field station when I left service in 1975. 

There was a new building built at Torii Station Okinawa before I arrived 
there in 1973. Every one though the new building was going to get new equipment. 
As a results no maintenance had really been done on a lot of equipment for two 
years. Then we moved all the equipment over to the new building and spent a 
year getting it up to par. We were so far in the hole on bad tubes we over run 
the maintenance budget and from the top command down every one wanted to know 
why it had cost nothing for maintenance for prior years and now we were 
spending money on parts like no tomorrow. Messengers were shot while approaching 
headquarters. They did not even want to hear it.

So Fellows, some where in this did I answer the question?

Roger AI4NI