[SignalOne] Re: SignalOne digest, Vol 4 #48 - 4 msgs

Wed, 10 Dec 2003 08:08:48 -0600

NIce to hear some fun stories about the CX7. I once restored one of 
these that was hit by lightening (many years ago). It was sure a 
project.

I now run a Mil Spec 1030 and would put it up against the best Japan 
has to offer - and beat them all. One thing ETO learned over the years 
between the CX7 and the 1030 was BUILD QUALITY!!!

I agree that, unless technical standards evolve to make SSB illegal, 
the old radios will be the signal source here from W0SY.

Gary

BTW: Thanks very much to Bob Turini for his advice on finding a 
complete owner's manual (copy) and complete service manual for my 1030.

On Dec 10, 2003, at 3:01 AM, [email protected] wrote:

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> Today's Topics:
>
>    1. CX7A ([email protected])
>    2. CX7A - Why am I doing this? ([email protected])
>    3. Re: CX7A - Why am I doing this? ([email protected])
>    4. RE: CX7A - Why am I doing this? (Pete Ferrand)
>
> --__--__--
>
> Message: 1
> To: [email protected]
> Date: Tue, 9 Dec 2003 06:42:04 EST
> From: <[email protected]>
> Subject: [SignalOne] CX7A
> Reply-To: [email protected]
>
> I bought the basket-case CX7A on eBay recently.
>
> This is the one that came "Guarenteed to arrive dead,  if this
> radio starts to work within 30 days, return for a full refund."
>
> No powercord, 4CX350F, wiring harness hanging out the back, voltage
> regulator connect to aft key jack, loose push buttons.  Did not come
> with the Beryllium block or the heatsink.  Did not come with the
> power supply for the 4CX350F.  Did not come with the blower or external
> ductwork for the 4CS350F.
>
> A fellow (not the seller, someone who wanted to help out) sent me a
> powercord. The radio powered up.
>
> Jitter on the 100 Hz digit.
>
> Dead PTO-B
>
> I opened PTO-B and fixed the tuning slug by glueing it to the carrier.
>
> Audio is strong, dual receive works.
>
> Passband tuning works.
>
> Keyer works but I can't use it.  It doesn't buffer the dits the way my
> TTL keyer does.
>
> Only has one CW filter, no AUX crystals.
>
> The QSK works.  I can hear the CW on another receiver but it is very
> weak.
>
> I'm hoping that the power transformer is good and that the wiring
> harness is intended to deliver higher voltages to the 4CX350F.
>
> Good S-Meter action, no indication of transmitter output.
>
> Noise blanker works.
>
> Seems sensitive and stable enough.  About the same as my SB-303. I have
> an SB-303 that is stable within a couple hundred Hz over a week and has
> dual cascaded 2.1 kHz filters.
>
> So, here's the problem. I'm thinking about restoring the radio to use
> an 8072.  I've read about problems with 8072.  What's the story with
> the 8072 and what's the deal with the 4CX350F?  It's mentioned the the
> Sullivan manual but no details.
>
> I don't have the CX7A hardware for the 8072 but have an offer of some
> GE landmobile RF power modules that include 8072's.
>
> Mostly I work on Heathkits (simple construction, detailed manual), this
> is a challenge.
>
> de ah6gi/4
>
>
>
> --__--__--
>
> Message: 2
> To: [email protected]
> Date: Tue, 9 Dec 2003 21:01:20 EST
> From: <[email protected]>
> Subject: [SignalOne] CX7A - Why am I doing this?
> Reply-To: [email protected]
>
> I've been refurbing an IC-720A.  Got it going at 95%.  The remaining
> anomaly is that the RIT doesn't work.  The IC-720A is "like" a small
> CX7A.
>
> Given that radios are pretty good now, that I have an IC-720A and
> working Heathkit SB's, why did I buy a basketcase, guarenteed dead CX7A
> on eBay?
>
> The answer is, because it's there.  I've been restoring and repairing
> Heathkits.  It's fun. I started a couple years ago when a hand surgery
> went bad.  My doc told me to work my fingers or I could lose some
> mobility.  I started refurbing an SB-303 to force my fingers to grip
> and twist.  I've been working on Heathkits, cleaning, adjusting. I
> discovered that I could take a "guarenteed dead", beater Heathkit to
> near showroom quality.  I discuss this at
>
>        www.kiyoinc.com/heathstuff.html
>
> When the CX7A showed up on eBay, it was too much to pass up.
>
> I drove an hour to get the delivery.  I opened it in my car, I
> couldn't wait to get it home.
>
> Later, I got the powercord.
>
> It was a thrill to see the CX7A come alive.  It was fascinating to open
> PTO-B and realize that the ferrite slug was loose and only needed a
> little glue to get working again.
>
> I attached a dual channel Tektronix LCD scope (with dual channel
> frequency display) to both PTO's.  I could see the waveform, output
> voltages, and the frequency.
>
> But a digression.  Last summer at the Berryville Hamfest, I spoke with
> a fellow, local big gun DX'er I guess, he had 3 Alphas for sale.  The
> deal was, he was reducing his collection and expected to sell only one.
>
> He wanted $900, $1,000, and some other amount for the better 374, the
> three holer. Strangely, you don't see that many big amps for sale.
> $900 for his lesser 374?
>
> The other week, a 374 went on the Bay.  I bid it up to $450 and dropped
> out. It sold for $650.  Not that bad.  If I had the cash...
>
> Signal/One, Alpha.  Unless there is a dramatic change in HF protocol,
> I'll be running my boatanchor stations for the rest of my life.
>
> I'm 56 and in good health so that could be a long time.  I'm not an
> electronics technician/engineer, I'm a software engineer (programmer
> with a Masters in Computer Science).  I do the hardware thing as
> recreation.
>
> I suspect that in 10 years, Signal/One, Alpha will be "like" running
> Gold Dust Twins.  Not because it's THAT good but because it is that
> interesting.  An integrated station?  Dual PTO's. 100 Hz readout.
> Passband tuning. RF clipping. Interesting.
>
> So my current project is the CX7A. No rush, if it takes a year, I'll
> get it going, put it back on the air.
>
> I am looking for parts, information, and technical advice.  The
> power supply is a mess.  There is a regulator with one lead cut.  There
> is a largish regulator on the back.  The HV is butchered.
>
> I need to understand how Signal/One designed the power supply.
>
> I know the issue of the Beryllium block.  My undergraduate
> degree is in chemistry.
>
> It's good to get feedback from Bob Sullivan (Mr. Signal/One
> maintenance) and I hope to work with Fern and his friend.
>
> I'm sending this through the list rather than replying directly
> because I think people like to read about fixing radios.
>
> de ah6gi/4
>
>
>
> --__--__--
>
> Message: 3
> From: [email protected]
> Date: Tue, 9 Dec 2003 22:08:35 EST
> Subject: Re: [SignalOne] CX7A - Why am I doing this?
> To: [email protected]
> Reply-To: [email protected]
>
> Thanks for sharing a good story.  I think we've got the bandwidth.  
> Amazing
> parallel here.
>
> Same boat (anchor), bought my CX-7A "guaranteed dead" at a hamfest a 
> couple
> years ago.
>
> Similar mod, 4cx250, forced air, noisy fan bearings, but got the rig 
> going in
> a few days, nothing major wrong (diodes, better lucky than smart in my 
> case).
>  The fellow I bought it from had kept the heat sink :)
>
> Wierd AC connector, homebrewed DC supply, homebrewed display board, 
> green
> LEDS, RIT mod with wrong size knob (but the original owner kept the 
> original knob
> :) :) all transistor locations fitted with pins to work as transistor
> sockets, Curtis keyer chip, God knows what else. If I'd understood at 
> the time what I
> had on my hands, I really would have questioned my sanity.
>
> Every time I turn it on, I expect it to smoke, but it just keeps 
> chuggin
> along.
>
> Every person that comes into the shack immediately wanders over to it 
> - when
> the dual receive is flipped on they flip out.
>
> Real radio guys seem to have cherished and modded these things way 
> beyond
> what people would consider doing to an S-line or similar.  And with 
> interesting
> results.
>
> I had to have mine because I remember hearing a few out of California 
> as a
> small tyke - first rigs with serious RF processing, what an amazing 
> signal that
> was at the time.  And the QST teaser adds, and then the real ads, more 
> fun.
> Way to go, ETO.
>
> No one could possibly blame ya for buying such an animal on E-Bay.  I 
> just
> can't understand how ya got it so cheap :)
>
>
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> --__--__--
>
> Message: 4
> From: "Pete Ferrand" <[email protected]>
> To: <[email protected]>
> Subject: RE: [SignalOne] CX7A - Why am I doing this?
> Date: Wed, 10 Dec 2003 00:04:51 -0500
> Reply-To: [email protected]
>
> I'm glad this thread came up. I, too, am seeking advice.....
>
> Several months ago I received what amounted to almost a donation from a
> friend of a CX7(no suffix) under circumstances that prevent me from,
> say, posting it on an auction site, not that I want to do this.
>
> Amazingly, the set works and even more amazingly it appears to be
> totally unmodified - original power supply, Nixies, etc. and rather
> lightly used, though the push button lettering is worn off as usual.
>
> I replaced the grid capacitor to avoid the total meltdown that led to
> the purchase of my $50 first CX7 23 years ago, and put it on the air 
> and
> it appeared to have nothing really wrong with it.
>
> So what's the problem? Well as most of us know, they need a bunch of
> mods, major ones in order to fix some messy problems.
>
> I've been stalling more than usual on this project because on one hand 
> I
> hate to tamper with what is probably one of the only such CX7's
> around.....on the other hand it's a great radio and I would like to use
> one on the air...but unmodified they aren't all that great with
> stability and signal purity problems, plus the need to protect the 
> power
> supply and so on. I have no available money to spend on rigs.
>
> Ideas?
>
> I've long since sold the first CX7, btw. Worked great but I had to
> replace just about every semiconductor in the thing.
>
> -Pete
> WB2QLL
> Enfield, NH
>
>
>
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