[R-390] Y2K Manual and CV-591

[Roy Morgan]

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!
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