[R-390] T401 alignment

[Roy Morgan]

On Apr 11, 2012, at 5:55 PM, chuck.rippel at cox.net wrote:
>
> A question to the group.  Anyone have documentation on how to tune  
> T401
> on the 2nd xtal oscillator deck?

Chuck and all,

I scanned my collected posts from the list, and a couple of saved web  
sites, and came up with the following LONG collection of discussions.   
The most complete is by Roger from  his "Trilogy", and is at the very  
end of this message.
Roy
Roy Morgan
k1lky at earthlink.net
K1LKY Since 1958 - Keep 'em Glowing!




In "HSN No 29 rewritten (wm).pdf"  I find:

"After the RF subchassis has been aligned, each of the ceramic crystal  
oscillator trimmers should be
peaked. Tune to any CAL signal in the band indicated above the trimmer  
(see Fig. 7) and peak the
signal. Not shown in Fig 7, eight of the trimmers can be peaked in  
either of two bands: 0-17, 1-18,
2-19, 3-20, 4-21, 5-22, 6-23, 7-24. After peaking such a trimmer in  
one band, you do not need to
peak it again in the other band. Peak T401 (also marked T207)."

In  ...Walt-Wilson-KK4DF/R-390A Alignment v2.htm  in the variable IF  
alignment section, the last steps are:
"Repeat the above until you no longer make big changes to the trimmer  
caps, then stop.

Set the signal generator to above 8MC (about 10 MC), and peak T208 and  
T401 for maximum diode load voltage."
and in the crystal oscillator section:
"Crystal Oscillator
You may use the CAL function for peaking the trimmer caps for maximum  
diode load voltage. But a better method is to use the line meter  
output and your ear with nothing but RF deck noise to peak each  
crystal for maximum audible noise and deflection of the line level  
meter. Peak the 17-24 MC trimmers at the lower bands (0-8 MC). After  
all are done, peak T401 (again) for maximum output at about 10 MC.  
T401 will peak differently on the higher and lower bands, so 10 MC is  
a compromise."
 From my collection of posts to the list, I find:
----- Original Message -----
From: "MURPH" <rickmurphy1001 at earthlink.net>
To: <r-390 at mailman.qth.net>
Sent: Wednesday, January 15, 2003 7:06 PM
Subject: [R-390] T- 401

 > What is the proper way to align T-401?
 > I peaked mine at 22mc with a DVM between e210  and ground with the
 > function switch in standby. Then peaked all trimmers on the module  
at their
 > appropriate  frequency.
 > Richard


From: "Keith Densmore" <densmore at idirect.com>
To: <r-390 at mailman.qth.net>
Date: Sat, 4 Aug 2007 10:56:44 -0400
Subject: [R-390] T207 T401

Greetings,
Perhaps I'm missing it, but I cannot find a procedure for aligning   
T207 ( 17meg) or T401 (crystal osc) in any of the books here.
Anyone know an accepted procedure for them?

All 73,
Keith ve3ts

From: Flowertime01 at wmconnect.com
Message-ID: <c50.1892745c.33e7b5cf at wmconnect.com>
Date: Sun, 5 Aug 2007 19:22:55 EDT
Subject: Re: [R-390] T207 T401
To: r-390 at mailman.qth.net

Keith,

You ask about,  a procedure for aligning  T207 ( 17meg) or T401  
(crystal osc)
--------------
You are correct.
For T401 the procedure is to run the MC to 31 and peak T401 and the  
cap for
maximum output.
In practice you find the MC band with the lowest output level and  
retune T401
to bring that band up enough to pass the 10:1 signal to noise ratio  
test on
that weak megahertz band. There is no one best absolute setting for  
T401. You
use it to get the bast of all bands out of it.
T207 the output of the first crystal oscillator is the same approach.  
That
transformer always passes 17Mhz. Pick any point under 8Mhz and adjust  
T207 for
maximum output on the diode load for minimum RF input at the antenna  
input.
You get like one clause of a sentence in the original TM on these  
subjects.
Hope this helps   Roger AI4NI

	From: 	Flowertime01 at wmconnect.com
	Subject: 	[R-390]  R390/A T401
	Date: 	March 15, 2009 12:42:23 PM EDT
	To: 	r-390 at mailman.qth.net
Richard,

Does anyone have an alignment process for the tunable inductor T401 in  
an
R-390A XTAL oscillator ?
----------
Very good question.

R390/A TM11-5820-358-35 Para 74 omits this subject. More than once we  
tried
to get it into a new edition of the TM. (1968 - 1975)

R390 TM11-5820-357-35 Para 77 give a procedure to do the alignment in  
the
R390. We just used this procedure on the R390/A.

I do not have my Y2K manual on this computer to see if the subject is  
covered.

 From the R390 TM.

Hang a Neg DC voltmeter into E210 grid test point of second mixer.


Set the slug of T401 at about 1/4 out from all the way in.
Set the receiver to 31 Meg.
Get a tweeker on the 31 meg trim cap in the osc deck.
Get a tweeker on T401.
Get the Voltmeter scale readable.
Spin the cap around.
It should peak twice.
Turn T401 out.
Spin the cap around.
It should peak twice.

Repeat
Turn T401 out.
Spin the cap around.
It should peak twice.

-------------
Or
Find the point of the trim cap between the two peaks. (max cap)
Adjust T401 out until the meter peaks)
--------------

At some point the cap it will only peak once. (max cap but not enough  
cap)

Now set the trimmer cap off peak a bit and reset T401 for max reading.
---Adjust T401 back in.

This should leave T401 peaked for best response.

You should get two peaks on the cap again.


Some times you will have a weak crystal or harmonic of the crystal.
Then you may do this process on that frequency with that trimmer cap  
to bring
the weak 1Mhz band up as best you can. Then retrim all the caps to  
T401 as
adjusted for the poorest crystal in the osc deck.

If the poor crystal will not let you trim it up and get every thing  
else to
pass, then it is time to change that crystal. This process being used  
to judge
when its time to call a crystal bad.

If you have a band that does not peak twice with the trimmer cap, this  
is a
band worth trying to reset T401 for higher output. You may have several
crystals that need to have the socket cleaned or the crystal replaced.

Adding small caps to bring a trimmer up to peak twice with T401 can be  
more
work than finding a different crystal that will work.

Roger Ruszkowski AI4NI

From: Bob Camp <ham at cq.nu>
Subject: Re: [R-390] T- 401
To: r-390 at mailman.qth.net, MURPH <rickmurphy1001 at earthlink.net>
Date: Wed, 15 Jan 2003 21:45:06 -0500
Hi,
That's been a debate here for as long as there has been a list. A few  
things people agree on:

1) Don't touch it after you have started peaking trimmers
2) If you run out of range on the trimmers moving T401 may help
3) If all the trimmers are in range (not at max or min) then there may  
be
room to fiddle T401
At that point the best advice is to peak it for your least sensitive  
band
*if* you can do that and still keep all the trimmers in range.
     Take Care!            Bob Camp            KB8TQ

This following message from Roger seems to be the most complete  
discussion of the topic:

From: Flowertime01 at wmconnect.com
Message-ID: <c4e.1ae1775d.33f0c3b0 at wmconnect.com>
Date: Sun, 12 Aug 2007 16:12:32 EDT
Subject: Re: [R-390] T207 T401
To: carolew at bellatlantic.net
Carrol,
...
This is long but I hope it provides some insight.
It is still not an exact step by step cook book.

The Second Osc alignment is about as clear as Mississippi River Water  
after a
summer rain. After reading the TM a few times the subject clears up.  
It looks
like the Beach Surf in Okinawa after a Typhoon just misses the Island.  
Once
you the do the alignment a few times the subject looks like the  
crystal water
and coral bottoms as viewed from the high beach cliffs of Okinawa and  
you
wonder what the fuss was all about.

The TM says align the second crystal oscillator caps from the Cal  
tones and
using the carrier meter as the output indicating level. That got some  
writer
off the hook back in 52 for the R390 TM and was copied into the R390/A  
TM. See
TM 11-5820-358-35 Paragraph 74 (page 114 in the 8 Dec 1961 printing) The
process works. And you can spread peanut butter on bread with a pop  
sickle stick.

But I digress and you asked me about T401 and the trimmer caps in the  
Second
Oscillator in the R390/A receiver.

The TM says there is no adjustment for 0 to 7. But we know 0 - 7 lays  
over
17- 24. The TM says start adjusting the caps for maximum carrier level  
output on
each Mhz band from 8 to 31. Mud in your eye. Do this from 31 down to 8.

There is one obscure clause of a sentence in the R390 TM that suggest  
that
T401 (numbered something else in the R390) be adjusted for maximum  
output at
31Mhz.

These two items, set T401 to max at 31Mhz and set C31 to max at 31Mhz,  
imply
these two adjustments will peak the output of the second crystal  
oscillator
for maximum receiver performance across all frequencies in the range  
of the
receiver. Another fantisy that passed muster with the TM editors. Hey  
it reads
good in Jargon with no sarcasm showing.

In real life do the following:
Turn the BFO off because BFO on masks the real signal level.
Set the receiver to MGC to defeat the AGC which will cause output meter
variations.
Hang a DC volt meter off the diode load as you choice of output  
indicator as
this is the most sensitive easily accessible point to meter the receiver
output.
Inject RF into the antenna input and use a level that gives a diode load
reading in the range of -5 to - 10 volts. The RF may or may not be  
modulated but
un modulated RF is mostly preferred for adjusting and testing.

The Receiver has a range of 31,000+ - 500 = 31,500 hertz. There is one
transformer (T401) and 24 caps that need to adjusted to optimize the  
second crystal
oscillators output such that all frequencies at the receivers antenna  
input
have optimum output at the headphone jack. Optimum output is left  
undefined as
an exercise for the operator to complete.

The first crystal osc mixes RF input under 7,000+ Mhz with a frequency  
near
17Mhz and passes it on to the second mixer. Between 17 Mhz and 24 Mhz  
the
second crystal osc uses a different crystal to mix that RF input under  
7,000+ Mhz
to a range of 3.455 to 2.455Mhz. The third mixer then mixes the VFO  
with this
signal to produce a signal at 455Khz. On a good day this signal is  
centered
into a crystal in the if deck with a band pass near 455Khz. Anywhere  
in the
frequency range you can grab the zero adjust the and slide the VFO  
around a bit to
peak the transfer.

The nonlinear VFO and its band spread will also impact the mixing  
frequency.
One end of the VFO or the other may add or subtract from any given  
second
mixer crystal error to increase the or decrease the receiver output.

So what good alignment? When do you quit?

Because the 17Mhz crystal is not exactly 17,000,000.000 you may find the
optimum cap setting for 18Mhz is not the same set point as for maximum  
1Mhz.

Like wise because some crystals at 17 -24 are not exact, the optimum  
setting
for one of them may not be the same for the double conversion and the  
single
conversion. If the 17Mhz crystal is off and the second mixer crystal  
is off the
differences may add to make things poor, subtract to make things OK,  
cancel
to make things good, do none of the above just to add reality.

Some of the second mixer crystals are used at more than one harmonic.  
You
have a different cap to peak each of these harmonics. The output level  
at the
harmonics may not be equal in amplitude or adjustable to equal  
amplitude while
each frequency has a nice double peak on it's respective trimmer cap.

The thought is that crystal output is highest at low frequencies and  
drops
off as frequency increases. If T401 is peaked at the highest  
frequency, it
response will drop off as frequency decreases. The slope of T401's  
output  plotted
against the slope of crystal loss across frequency is considered to  
yield a
near flat mixer output across the frequency span.

Thus the TM read to peak T401 at the highest frequency and adjust each  
cap in
the second crystal osc deck from 8 to 31 Mhz. The procedure details  
using the
Cal tone, BFO and carrier level meter. Me know this process is not the  
most
sensitive.

We would like to think that peaking the trimmer caps only changes the
impedance match to yield a better power transfer of the oscillator  
output and that
the cap adjustment does not vary the frequency of the crystals. We  
would like to
think every crystal is spot on exact to within under 100 hertz and  
stable as
a rock.

What we find is one or more crystals have an output level below the  
curve.
If it is off frequency, and in the range of the zero adjust, then zero  
adjust
the VFO and peak the cap for the megahertz band and move on. This is  
just an
off frequency crystal but still in specification. If the zero adjust  
it peaked
and the output is low then the oscillator output is weak for that  
band. Try
cleaning the crystal contacts, the tube contacts and the cap. But the  
first
easy quick fix in a clean receiver where you know corrosion is not the  
problem
(1968 - 1975 era) is to adjust T401.

You slide the low frequency slope of T401 down. This lets more of the  
crystal
output from the weak crystal through the circuit to bring the weak  
band up to
par. You hope the top frequencies do not go so far over the hump they  
fall
under par.

You find the low spot (a dip / a weak output crystal) in what would be  
the
curve of the crystal output levels. Then move the cutoff slope of T401  
by
adjustment so that when the two functions (crystal outputs / T401  
cutoff slope)
cross, the output performance level of the second osc is of acceptable  
performance.

Start at 31 Mhz and adjust T401 and cap 31 for maximum output. Use a RF
signal generator and DC volt meter on the diode load for best  
indication of
adjustments.

Continue down the bands in frequency to 8 Mhz. Adjust each cap but do  
not
reset T401 while doing these adjustments.

Mark the 17 - 24 cap setting (pencil on the deck in line with the screw
driver slot) and continue down in frequency.

Reset the caps for best output on the 7 - 0 bands.

Look at the cap settings when you complete this process.
Are the caps still peaked at the same alignment point?
Are the 17 - 24 caps not all offset the same way (17Mhz crystal off
frequency)?
Are the 17- 24 caps set above and below (the second crystals osc  
crystals off
frequency)?

Now you have a choice.
Peak the caps for the low band (0-8) or the high band (17-24) or balance
between the bands.

If in the process of aligning the whole receiver you find one or some  
of the
1Mhz bands to be low you can now think about readjusting T401 to bring  
the
bands up to par.

First consider if you have done all the other adjustments on the  
receiver.
Working over 17- 31 Z206 and T206 will yield more improvement than  
trying to
optimize T401 and C20 to bring up a weak 20Mhz band.

Second consider if you have a clean machine.
Clean contacts under, caps, transformers, tubes, crystals and  
connectors go
further than peaking adjustments.

After you adjust T401 to bring up some low band you should then go  
back and
check all the other caps. What ever the last setting for T401, peak  
all the
caps without ever touching T401 again.

The TM implies that setting T401 is not an exact most critical  
adjustment.
The TM further implies that just close with a cal tone and carrier  
meter is good
enough. But after 50 years, consideration and attention to detail can  
get
more out of these adjustments than just a good receiver.

Put some time into your receiver working through these adjustments to  
come to
an understanding of how your particular receiver balances out. In the  
end you
will have a better receiver to listen too.

There are many other stages in the receiver that can compensate for the
elected less than exact test book adjustment of the second crystal osc  
deck.

Once you understand what bands of the receiver you want to optimize  
for your
use, how the many adjustments interact and the limits of the exact  
parts in
your exact receiver, you find a pattern of adjustments that optimizes  
the
receiver for your enjoyment.

I hope this helps.   Roger L. Ruszkowski AI4NI