[Hallicrafters] R-274 Band VI Update to the Update

[thoyer]

I Finally got this beast to the point where I'm happy with the operation.
Took some final pictures and put the covers on. It cleaned up real nice and
I think it works pretty well. Now to find a place in the shack.....

I ended up swapping around a few tubes, reworking the alignment a bit and
rewinding one of the antenna input coils. My sensitivity measurements are as
follows, I'm just going to list the band average, not points - too much
typingat the end of the day........

Band 1, 3.5uV
Band 2, 8uV (I could tinker a little more here but it seems to receive well
so I'm leaving it for now....)
Band 3, 5uV
Band 4, 4uV
Band 5, 4uV
Band 6, 20uV (they have no spec in the manual for band 6. I'm guessing it
should be better, but....)

Here is a link to some pics kind of start to finish. At the end is a video
of it playing.

http://www.thdesignsinc.com/R-274.html

I'm going to call this a wrap so thank you to everyone for your tips and
guidance as well as parts!

Tom
W3TA


PS: need to decide whats next on the bench.... CR-88, SP-600 or go "light"
and finish up the 51S-1 I started several months back (needed some parts
that I just got) or the SX-117. Decisions, Decisions.....



-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of thoyer
Sent: Tuesday, February 20, 2018 9:00 PM
To: 'Jacques Fortin'; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] R-274 Band VI Update

Correction, I found out that band VI operates on the second harmonic of the
VFO (missed the fine print in the manual until it was pointed out to me....)

Took some readings tonight:

Went back to the "as built" configuration and took some measurements at V3-1
the input of the VFO to the first mixer.

Using a Fluke Scopemeter set to read Vpp and freq. I took two readings on
each band - main tuning fully CW(high end of band) and main tuning fully CCW
(low end of band). Results:

Band 1 CCW = .983mhz, 30vpp
Band 1 CW = 1.744mhz, 62vpp

Band 2 CCW = 1.7mhz, 23.3vpp
Band 2 CW = 3.485mhz, 54vpp

Band 3 CCW = 3.4mhz, 20vpp
Band 3 CW = 7.5mhz 58vpp

Band 4 CCW = 12.82mhz, 8.5vpp
Band 4 CW = 19.86mhz, 18vpp

Band 5 CCW = 19.2mhz, 2.2vpp
Band 5 CW = 32mhz, 4.5vpp

Band 6 CCW = NADA
Band 6 CW = 27.34, 6.7vpp

Watching the scope while tuning through band 6 the oscillator stops working
around 20mhz on the scope, 36mhz on the dial which may or may not be
close...

I also noted that while tuning through the bands and monitoring the voltage
on V3 pin1, it increases and decrease several times on the higher bands. At
some points it gets so low that I wonder if any signal would be heard. 

I don't have much time tonight to "play" tonight so until tomorrow........

I'm open for suggestions....

Tom
W3TA
 

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of thoyer
Sent: Tuesday, February 20, 2018 7:10 PM
To: 'Jacques Fortin'; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] R-274 Band VI Update

Hi Jacques, 

The coil only has about 6 turns on it wide spaced so no possibility of a
short there. I did look at the slug in the coil and it appears intact and
does "tune" the resonant freq with adjustment.

I re-read the theory of operation and it appears that band 6 functions just
like the other higher bands VFO signal plus 6mc.

I'm about to go work on it now - we'll see what happens tonight....

Tom

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Jacques Fortin
Sent: Tuesday, February 20, 2018 1:57 PM
To: 'Thomas Hoyer'; hallicrafters at mailman.qth.net
Subject: Re: [Hallicrafters] R-274 Band VI Update

Hi Tom,
You could have a short between coil turns or the ferrite slug within the
coil (if there is one, say) is the bad one.
Are you sure that this top band do not works "in reverse" , meaning having
the LO working BELOW the received frequency by the value of the first IF ??
Just ideas.... remembering that your set was beaten up before !

73, Jacques, VE2JFE

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