[R-390] Y2K Manual and CV-591

Mon Nov 14 18:01:40 EST 2005

In a message dated 11/14/2005 11:27:11 AM  Eastern Standard Time, 
roy.morgan at nist.gov writes:
At 10:25 PM 11/11/2005,  Bonddaleena at aol.com wrote:
>
>I intend to start 'going through' my  working and very mint '67 EAC.

Ron,

Good for you. I also have a  nice EAC-67 here. Mine is kaput, but I'll get 
it working nicely when I get  to it.

>...I have the very nice Y2K Manual. I
>  was just  wondering if anyone has an 'erratta' list for the Manual.

First, make  sure you have the "Release 2" version. It is  here:
http://www.r-390a.net/Y2K-R2/

On that page is a set of errata  for the Release 1, but as far as I know 
they have all been accounted for in  Release 2.

There may well have been some errors detected in Release 2,  but I don't 
know of a list of them.

>  I do have a couple of  questions on the 591A........
>
>1. For some bizzare reason, the USB  and LSB positions appear to be  
reversed.

This is an oddity but not  unexpected.  The thing can be used with receivers 
that either reverse  the sideband sense or do not reverse it. This comes 
from the local  oscillator being above or below the mixer input 
frequency.  The manual  for the 591 talks about this situation. You man have 
discovered that the way  to "switch" the thing is to reverse the bulb covers 
on the two indicator  lamps!

>I had to switch xtals to get it to detect the SSB signals as  indicated  on
>the front panel. According to the 591A Manual, the  xtals were in the correct
>position, but I had to switch them, to get it  to function correctly.

Good if it works for you, fine.  The whole  thing is a bit of a puzzle for 
me, at least, even though you'd think it was  easy to understand and keep 
straight.

>Could the 390A be THAT far  out of alignment? The audio sounds great with  
the
>xtal swap,  but......somethin' ain't right.

I suggest you get a signal generator and  do a little experimenting. Think 
slowly. Turn the knob slowly.  Get  clear in your head where the signal 
generator is with respect to the  passband and the local oscillator(s)

For example: if you tune your signal  generator from ABOVE the frequency the 
receiver is tuned to, and the first  audio you hear it HIGH frequency (like 
2-3 kc) and decreasing, then your  signal generator signal is above the 
tuned frequency and you are in the  upper sideband.

>  2. Never having used this combo before, I was  VERY disappointed with the
>audio output of the 591A.

I think you  are not the only one. I suggest you make VERY sure that the 
coupling caps in  the 591 are replaced: especially the ones in the audio 
section. ALL, repeat  ALL EACH AND EVERY ONE of the coupling/bypass caps in 
my CV-591are leaky. In  the audio section, this causes excessive plate 
current in the audio output  tube.  In particular, C20 and C24, both 0.01 uF 
may be leaky. C24  especially may be leaking and driving the 6AQ5 plate 
current way up, causing  lots of distortion and weak audio. Test also C25 
and R24, cathode bypass and  dropping resistor for the 6AQ5.  Measure the 
cathode voltage to be sure  nothing is amiss. replace all three of these 
caps, unless C25 is a paper oil  (2 uF) and is not leaky or defunct.  Try 
feeding audio into the thing  at the appropriate place to see if the whole 
audio section is workingl.  Modulated 455 kc from the signal generator will 
tell you a lot,  too.

>  I have to use an outboard audio amp to get  decent
>volume.

Notice that the audio output section is  configurable for "low level" 
output  (150 mW)or "high level" (2 W) and  also can drive 8 ohms or 600 
ohms.  Dope that out in your mind and get  it set up straight.  The switch 
that does this is on the chassis near  the rear terminal strip, I think.

>  Tubes are good, been  recapped, voltages normal etc. Any thoughts? I do
>have a junker 591A I  picked up because the filter choke in mine was fried.

Of course you don't  need the junker now, so send it to me.. thanks. (heheh)

>  I  don't mind using the outboard amp. In the same rack, is a 51J-3 with  a
>solid state (Ron Hankins?) SSB adapter. Of course, this one absolutely  
>needs an  outboard amp.

You mean the 51J-3 absolutely needs  an outboard amp, or the SSB adapter 
needs it?  I have an R-388 that I  have not yet got running, so that's why I 
ask.

>  I just  thought the 591 with it's 6AQ5 audio tube should provide as  much 
>  volume as my other boatanchors which use the same tube.....

That makes  sense, but it may simply be lame by design.  How does it sound 
with  good earphones??

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em  Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Cell  301-928-7794
Work: Voice: 301-975-3254,  Fax:  301-948-6213
roy.morgan at nist.gov  --

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Hi Roy, good to hear from you again.... We corresponded a couple of years  
ago, when I was N4KCM.
I always respected your answers.

I had a couple of R-388s and loved them. I eventually came across this mint  
51J-3 so it became a 'keeper'. Sorry for the confusion about it's audio...

No, the radio has PLENTY of audio. Ron's adapter is plugged into the 500KHz  
out jack and it have virtually no audio, but a flea market audio amp works  
perfectly!

I poked around under the 61J-3 and lo and behold, no paper caps to change!  
They are all dogbones. The sensitivity even on 10M is amazing!!!

On the 591, I replaced every cap in there. It works great, except it has  low 
audio.

I use Dr. Jerry's method of cap checking and it is fantastic!

regards,

ron

N4UE