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Author Topic: AC5UP had one of these ..................  (Read 4160 times)
N2EY
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« Reply #15 on: October 15, 2011, 09:34:21 AM »

Just my opinion- the price they bring is 100% because of the rarity, not their function.

Dale - thanks for the info. Great stuff - I always wonder how good some of the rare ones really are.

You mention the RME-4350A. I've always wanted one - better yet, a 6900. But they seem rare, and I've heard the dial drive is fragile. True or false?

IMHO the SX-88, despite its rarity, did have a lasting effect on receiver design. From what I see, its method of double conversion (bandswitching tunable HFO, two fixed IFs, first IF around 2 MHz, second IF around 50-60 kHz giving multiple selectivity levels from LC IFTs) was widely used in other Hallicrafters receivers (S-76, SX-96, SX-100, SX-101, etc.) and other brands (NC-300, NC-303, RX-1, etc.)  Meanwhile the idea of a single-range tunable first IF (often on a ham band) with crystal-controlled downconversion remained the domain of Collins and homebrewers until the Drake 1-A.

Imagine a little 1-A, 2-A or 2-B side-by-side with an SX-88 on SSB - and doing a better job.

73 de Jim, N2EY
« Last Edit: October 15, 2011, 09:37:17 AM by N2EY » Logged
G3RZP
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« Reply #16 on: October 15, 2011, 11:52:06 AM »

Before WW2, there were receivers around with double conversion. The R1116 used in the Fleet Air Arm Swordfish biplane (the 'Stringbag') had a 100 kHz IF for bands up to around 2 MHz and then 1.7MHz first IF and 100 kHz second IF. The DST100, used mainly by British Embassies and appearing just pre WW2 was also double conversion with 2MHz and 100 kHz IFs. An article in the RSGB Bulletin in 1944 recommended the crystal controlled front end and tuneable IF.

According to my father, Hallicrafters were often referred to in the UK pre WW2 as 'hallycrapters' - AC5UP, please note! Basically because it was their cheapest nastiest receivers that made it over here. Although the S27 and S36 proved very useful for the Battle of Britain...The 'ne plus ultra' on those days was definitely the HRO: then the RCA AR88. The advantage of the HRO, besides the bandspread, was the much lower weight!

And what would the allied war effort managed without Hallicrafters, Hammarlund, Collins, National, Eimac, Meissner, Millen, Heinz and Kaufmann etc?

I venture to say nowhere near as much as they did.....
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AC5UP
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« Reply #17 on: October 15, 2011, 12:04:13 PM »

Hallicrafters were often referred to in the UK pre WW2 as 'hallycrapters'

Over here it tends to be " Halliscratcher " for the alleged poor audio quality of some models.......... The other is the Heathshkit Apache TX-1 AM transmitter often referred to as " The Scratchy Apache " due to the low level modulation scheme designed by someone they pulled off the sidewalk at random in Benton Harbor.

http://www.heathkit-museum.com/ham/hvmtx-1.shtml

Some folks swear by them, others at them.  Grin
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W4OP
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« Reply #18 on: October 15, 2011, 01:34:57 PM »

I think the issue with the 4350's drive mechanism is perhaps because it is misunderstood.  I have worked on two of  them now- neither worked when I got them. Both are now excellent. There are 2 ball bearing races and a tensioning plate. I guess if someone overtightened that plate, it could cause some wear. But they appear pretty much indestructable. I think the issue may be the coupling to the  main tuning cap that self adjusts for both angular and colinear mislaignment. On one of the 4350's I replaced that coupling with one that allowed for just angular mislaignment- as the original with its spring loading was causing backlash.
The 4350 is really neat in that  you can tune very slowly with the outer knob, OR cover an entire band in a second by grasping the inner knob.

The only drawback is the  lack of AGC on SSB/CW (typical BFO). I am working on an audio derived AGC for those modes that will be transparent to the operation

I should also comment on the sensitivity. Even on 10M  one can easily hear the change in background noise as the  ANT TUNE control is peaked- lots of front end gain.

The 6900 is another animal-  a real bear to work on. ER did an article on the 6900 some years back and that has disuaded me from ever purchasing one.

Dale W4OP
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N2EY
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« Reply #19 on: October 15, 2011, 06:38:37 PM »

" The Scratchy Apache " due to the low level modulation scheme

What "low-level modulation scheme"? The Apache is plate modulated!

(Of course it uses expensive audiophile tubes {6CA7/EL34} in the modulator, which seemed like a good idea at the time...)

73 de Jim, N2EY
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AC5UP
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« Reply #20 on: October 15, 2011, 07:02:37 PM »

What "low-level modulation scheme"? The Apache is plate modulated!

Then maybe I'm thinking of another Heathshkit, like a DX-60......... ?
I know I've heard the phrase " Scratchy Apache " more than once and figured it was low-level or screen modulated. Thanks for the clarification.
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N4NYY
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« Reply #21 on: October 18, 2011, 04:04:46 PM »

Nelson,

I just received my AA5 book from Amazon. I am officially dangerous.
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KC2VDM
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« Reply #22 on: October 18, 2011, 04:32:54 PM »

God help us!  Grin
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N2EY
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« Reply #23 on: October 19, 2011, 01:18:34 PM »

Then maybe I'm thinking of another Heathshkit, like a DX-60......... ?
I know I've heard the phrase " Scratchy Apache " more than once and figured it was low-level or screen modulated.

The DX-35, -40 and -60 were indeed low-level modulated. Controlled-carrier, actually. Still not that many watts from a 6146, but it was cheap.

DX-100 and TX-1(Apache) were plate modulated. However, as I understand it, Heath limited the low end response by using small coupling caps in the audio chain, resulting in "thin" audio.

The TX-1/Apache used a pair of 6CA7/EL-34s to plate-modulate a pair of 6146s. All the tube books I've seen rate the 6CA7/EL-34 at 450 volts B+ and maybe 50 watts audio max. Kinda on the thin side IMHO, those tubes were working hard to make 75+ watts of audio. Maybe they used some tricks. Not a lot of head room in any event. The DX-100 used a pair of 807s or 1625s (I think the B went to 807) which is better.

Note that the Eico 730 modulator also used a pair of EL-34/6CA7s, but was only intended to modulate a single 6146!


73 de Jim, N2EY
« Last Edit: October 19, 2011, 01:22:58 PM by N2EY » Logged
AC5UP
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« Reply #24 on: October 19, 2011, 03:12:38 PM »

Don't get me started......... At least the 6CA7 is still widely available from international sources brand new and in the box from $14.00 per tube up to $85.00.......

Check this out: http://thetubestore.com/sh-6ca7-z.html

Not the first time we've seen golden tubes, but this one has a price to match. I love the advertising copy: "...to accomplish directional solidification and single crystallization". Throw in a flux capacitor and you can do some traveling with a tube like that. Surf the web tube boutiques and you'll also learn that genuine Tung-Sol tubes are made in Russia. Whooda' Thot?

But wait... There's more: http://thetubestore.com/ampohmreviews.html

Betcha' you didn't know that paper / oil tubular caps are the really, really good kind. Especially with copper foil. And before you judge how much they've improved your amplifier, give them time to break in and reach the fullness of their sonic potential.

Gag me with an Extralytic.........................  Tongue

BTW: Another little gem I found this week is a modest stash of Sprague Orange Drops marked .1uf @ 1,000 vdc. It's a manly capacitor.
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N4NYY
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« Reply #25 on: October 19, 2011, 03:22:05 PM »

Quote
BTW: Another little gem I found this week is a modest stash of Sprague Orange Drops marked .1uf @ 1,000 vdc. It's a manly capacitor.

Those are top quality caps. I little on big size physically. Audiokooks go nutso over them.

Last week, I was helping an elderly ham clean out his stash, and I came across a HUGE box of tubes, labeled 500Z. I asked if they were any good, and he said no one used them anymore. So we trashed them.
« Last Edit: October 19, 2011, 03:34:51 PM by N4NYY » Logged
N2EY
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« Reply #26 on: October 19, 2011, 03:30:02 PM »

Throw in a flux capacitor and you can do some traveling with a tube like that.

GREAT SCOTT!!!

You mean an interocitor.

It's a manly capacitor.

Manly yes, but I like it too.

73 de Jim, N2EY
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AC5UP
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« Reply #27 on: October 19, 2011, 03:46:42 PM »

Quote from: After Visiting The Heathshkit Hall Of Shame, B+ Vinnie Wrote:
So we trashed them.

That's what I would have done with the 3-500Z's.............. If they were 3-520Z's I'd have kept them, but the 500Z's? Fuhgedaboudit.

On a similar note... This is no joke and I think you'll appreciate it. Long ago and far away I was a stoodint at a large university located on North Broad St. in Philadelphia (think Bill Cosby). One early spring afternoon I was loitering in the loading dock behind one of the TV studios in Annenberg Hall and spied a large and truly old chassis of some ancient electronic device. Turns out it was the guts from a late 30's vintage Wurlitzer electronic organ.

No kidding, you wouldn't believe the tubes in the tone generator deck. All 6W7's. I was told it was being thrown out and I was welcome to swipe parts.

So I acquired some trash can liners from the men's room and liberated all the glass bottles. Probably 50 to 60 of them. They're still in my garage.

And, in case you're wondering, the organ was a donation from WPVI-TV and was last used years before on a Sunday morning TV show that became popular in the 50's................ Dude who played it was named Larry Ferrari. (WA2MKI -SK)

Go Figure, I still have some of Larry Ferrari's organ. Shocked
In a manner of speaking..............
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AC5UP
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« Reply #28 on: October 19, 2011, 04:03:10 PM »

BTW: I can tell this dude is from New Jersey without looking at the call:

http://4.bp.blogspot.com/_N_-W1PmSNqg/SVWhrG7wNjI/AAAAAAAAI6U/_ppsTRfry-Y/s1600/2008%2BBOB%2BGARNIER%2BWA2AFT.jpg

How?

Monobrow.....................................  Cheesy
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N4NYY
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« Reply #29 on: October 19, 2011, 06:58:32 PM »

That is fantastic! I wonder if the RF illuminated that shirt?
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