[CW] Mackay 3010B tube receiver
Richard Knoppow
1oldlens1 at ix.netcom.com
Sun Sep 15 22:35:08 EDT 2019
See the handbook at BAMA.
http://bama.edebris.com/manuals/mackay/ITT3010C '
The differences between the B and the C are detailed on the
first couple of pages.
There was also a Mk2 version but I have not been able to find
out anything about it.
The receiver illustrated at W1VD has an addition in place of
the antenna filter. I am not sure what this is because its not
high rez enough to read. The standard antenna filter is a
broadcast band stop band filter to eliminate overloading when
near broadcast stations, as in port. The handbook states that
other bands can be special ordered. Its possible that the extra
knob there is for selecting among several, but again, I can't
make it out.
One thing I am curious about is whether any sort of option
was provided for a slow release AVC. I think it would not be
difficult to add a modification for this.
I wonder if the one you are trying to sell has the optional
narrow band CW filter in it. The SSB and CW filters were the ones
used in the Collins 75A-4 so probably the 1500Hz, 800Hz, 500Hz
filters were available.
I would love to have one of these but any reasonable price is
way beyond my budget.
I got curious about them recently and dug up as much info as
I could find.
On 9/15/2019 6:53 PM, D.J.J. Ring, Jr. wrote:
> It was my understanding from reading manuals years ago that the C
> model added product detector.
>
> Now is over 40 years ago, so my memory might be corroded.
>
> 73
>
> DR
>
> On Sun, Sep 15, 2019, 21:46 Richard Knoppow
> <1oldlens1 at ix.netcom.com <mailto:1oldlens1 at ix.netcom.com>> wrote:
>
> Check to see if its really a C. About the only difference is
> the addition of a TC cap in the VFO. The manual for the C says B
> on it but has the additions for the C.
> There is a manual with specs at BAMA under MacKay.
> I don't know who actually built these but probably Federal
> Radio, who was the manufacturing division of ITT.
>
> On 9/15/2019 6:13 PM, D.J.J. Ring, Jr. wrote:
> > I have a Mackay 3010B that Quincy Electronics gave to me
> in hopes
> > of selling it.
> >
> > Info here: http://www.w1vd.com/Mackay%203010B.html
> >
> > *Mackay 3010B*
> >
> >
> >
> >
> >
> >
> >
> > *Front end attenuator OFF:*
> >
> >
> > *Band* *MDS* *Blocking* *Two-tone D.R.*
> >
> >
> > *(20 kHz)* *(20 kHz)*
> >
> >
> >
> >
> > 80 meters -146 dBm 93 dB 68 dB
> > 40 meters -141 dBm 96 dB 67 dB
> > 20 meters -140 dBm 102 dB 68 dB
> >
> >
> >
> > *Front end attenuator ON 1st position:*
> >
> >
> >
> >
> >
> >
> > *Band* *MDS* *Blocking* *Two-tone D.R.*
> >
> >
> > *(20 kHz)* *(20 kHz)*
> >
> >
> >
> >
> > 80 meters -135 dBm 94 dB 66 dB
> > 40 meters -128 dBm 98 dB 69 dB
> > 20 meters -126 dBm 103 dB 69 dB
> >
> >
> >
> > *AM Audio S/N:* 43 dB
> >
> >
> >
> >
> > *AM Audio Frequency Response: *
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > *100 Hz* *200 Hz* *400 Hz* *600 Hz*
> *800 Hz* *1 kHz* *2
> > kHz* *3 kHz* *4 kHz* *5 kHz* *6 kHz*
> >
> >
> > -4 dB +1 dB 0 dB +2dB +2 dB 0 dB -2
> dB -10 dB -24 dB
> > -40 dB -
> >
> >
> > *AM Audio Distortion: *
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > *Mod%* *100 Hz* *200 Hz* *400 Hz*
> *600 Hz* *800 Hz* *1
> > kHz* *2 kHz*
> >
> >
> > 30% 13% 8.9% 7.1% 6.3% 5.6% 4.5% 4.0%
> > 50% 13% 7.9% 6.3% 6.3% 6.3% 6.3% 7.9%
> > 70% 20% 13% 11% 10% 7.1% 6.3% 7.1%
> > 90% 32% 22% 16% 14% 11% 7.9% 7.9%
> > 100% 40% 25% 18% 16% 13% 8.9% 8.9%
> >
> >
> >
> > *Notes:* This receiver is pretty uncommon so a few
> comments are
> > in order. With 0 dB front end attenuation and maximum i-f
> gain
> > this receiver has extraordinary gain and sensitivity -
> especially
> > at the lower frequencies. Designed mainly as a shipboard
> receiver
> > it is likely this receiver would have performed well on
> 500 kHz
> > with the ships antenna fully encrusted in ice and laying
> on the
> > deck! Words can not adequately describe the unbridled gain of
> > this receiver - you'll just have to try one for yourself.
> >
> > The receiver is extremely well built on a cast aluminum
> > foundation in which individual stages occupy their own
> > compartments. DC and bias voltages enter through feedthrough
> > capacitors and signal openings from compartment to
> compartment
> > are kept as small as possible. One wishes all receivers were
> > built this way!
> >
> > Unfortunately, the blocking and two-tone dynamic range
> numbers
> > tested disappointingly low - even with the i-f gain of the
> > receiver cut way way back. Considerable time was spent to
> insure
> > that the receiver was functioning, as best as one can
> tell, to
> > factory specifications. All voltages were correct, as was LO
> > injection levels when compared with the figures given in the
> > manual. The rf circuitry used is somewhat unconventional. The
> > receiver covers from 70 kHz to 30 MHz and uses up
> conversion to a
> > first i-f of 38 MHz. The main signal path includes a manually
> > switched front end attenuator, manually switched front end
> > bandpass filters that feeds a single stage 7788 tube rf
> > amplifier. Signal from the plate of the rf amplifier passes
> > through a 14 section 30 Mhz low pass filter. This is
> applied to a
> > 6C4 cathode follower that feeds the first mixer - a quad
> of 1N82A
> > 'VHF' diodes in a balanced design. The signal is amplified
> and
> > filtered by two tuned circuits, a single 6688 amplifier
> tube and
> > two more tuned circuits. A 6BL8 triode section forms another
> > cathode follower which feeds the grid of the 6BL8 pentode
> section
> > as the 2nd mixer with an output at 5.94 MHz. A somewhat
> unusual
> > arrangement has the LO injection in series with the rf
> signal to
> > the grid. The plate of the 2nd mixer passes through a 6
> kHz wide
> > crystal lattice filter. From there it's on to the third
> mixer - a
> > 6BE6 converter stage - for the final i-f of 455 kHz. Here,
> the
> > signal encounters the Collins mechanical filters for
> either SSB
> > or CW. No additional filter is used here for AM - just the
> 6 kHz
> > filter in the previous i-f. The remainder of the circuitry is
> > pretty straightforward. One nice feature of this receiver
> is that
> > it does have a product detector.
> >
> > This receiver was on loan so it was only possible to
> observe its
> > performance - not modify the receiver to try to improve
> it. In
> > order to locate the source of the poor dynamic range a high
> > impedance probe / spectrum analyzer setup was used to
> 'sniff' IMD
> > stage by stage. The culprit turned out to be the 6BL8 second
> > mixer stage. With simple tests and limited time I was
> unable to
> > determine the exact cause of the poor IMD performance but
> would
> > suspect the 6BL8 biasing, or more likely the crystal
> filter in
> > the plate circuit or the VFO amplifier which has it's
> output in
> > series with the rf signal. Even if the IMD could be
> improved in
> > the second mixer, next in line is the third mixer - a 6BE6
> > converter - generally a dynamic range 'show stopper' in
> receivers
> > where it's used. This would be one fun receiver to modify for
> > truly high performance!
> >
> > The AM distortion numbers show the somewhat typical
> increase at
> > lower audio frequencies - most often caused by the low audio
> > frequencies riding on the AGC line. Also there is the usual
> > increase in audio distortion as the modulation percentage
> > increases. This is due to the detector's inability to cleanly
> > demodulate the higher amplitude levels although this receiver
> > does pretty well.
> >
> >
> >
> >
> > It probably works but there is no schematic and there is
> no power
> > plug. The power plug it appears is like a vacuum tube octal
> > plug. It has no outer cabinet, it's rackmount.
> >
> > Obviously there are other connections there as well.
> >
> > I'd have to crate it - either in wood or cardboard.
> >
> > Then mail it - it's heavy.
> >
> > You have to either pick it up in Marshfield, MA or have me
> pack
> > it and post it.
> >
> > Cardboard is cheaper but I know a carpenter who can make a
> box as
> > long as the box keeps the package under 70 pounds, it's
> good to go.
> >
> > Inside the crate will be anti-vibration materials.
> >
> > You're paying for all of this if you want me to post it.
> >
> > Or you can pick it up where I live. Free no extra cost..
> >
> > Make a reasonable donation $100 or more and agree to pay the
> > shipping cost and it's yours.
> >
> > 73
> >
> > DR
> >
> > ______________________________________________________________
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> > =30=
> >
>
> --
> Richard Knoppow
> 1oldlens1 at ix.netcom.com <mailto:1oldlens1 at ix.netcom.com>
> WB6KBL
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--
Richard Knoppow
1oldlens1 at ix.netcom.com
WB6KBL
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