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Clegg Zeus modulator




 
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Author Topic: Clegg Zeus modulator  (Read 4579 times)
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VE3AJM
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« on: September 11, 2015, 10:28:58 AM »

I obtained a Clegg Zeus modulator/PS last week, no tx. Looks like it has a lot of possibilities with a pair of 811as in the modulator and cathode follower audio drive. Lots of audio frequency restricting components there too.

Anyone on here ever modified one for use with an HF class C amp, and for better audio frequency response? I have my own ideas about it, both in the PS and audio, but would welcome any of your ideas. Thanks.

Al VE3AJM
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w4bfs
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« Reply #1 on: September 11, 2015, 10:58:28 AM »

I would love to find one of those .... I have a Viking 500 rf deck without ps/modulator .... hard to find schismatic diagram for those .... nice catch
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Pete, WA2CWA
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« Reply #2 on: September 11, 2015, 12:55:36 PM »

The Zeus PS/Modulator is not a stand-alone modulator. The input mike connection and the several stages of speech amplification were located in the transmitter cabinet.
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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
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« Reply #3 on: September 11, 2015, 01:17:44 PM »


    A couple 3 years ago I had a customer in the same boat. He
supplied the iron and I made a V-500 P. Sup/Modulator deck for him.
The MOD Iron was from a Zeus.

   It worked fine. I have the manual on the 500 in pdf, and some info
on the Zeus, in .gif.  What info do you need?

/Dan




I would love to find one of those .... I have a Viking 500 rf deck without ps/modulator .... hard to find schismatic diagram for those .... nice catch


* v500 003.jpg (986.42 KB, 2736x2052 - viewed 324 times.)
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w4bfs
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« Reply #4 on: September 11, 2015, 01:25:34 PM »

fb Dan ...if you don't mind either on the forum or email the .gif on the Zeus .... tnx 73   John
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Beefus

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VE3AJM
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« Reply #5 on: September 11, 2015, 04:57:34 PM »

Good information. Thanks guys. I've been looking at some of the schematics on and off today. I will get the unit working as is for now with a Viking II or something and go from there. I have a 12AX7, 12AU7 or BH7 HB speech amp that I can use with it.

B+ voltage approx. 900v, choke input fullwave rectifier, 2 5R4 rectifiers, common supply for the 7034 final and 811a modulators. There are no specs on that plate transformer in the parts list but the schematic does show it as 2200v rms. 1100-0-1100, but nothing for current rating as far as I've seen. 200ma for the 7034 or 180 watts dc input on phone, and approx. 120ma peak or so for the 811as, so perhaps 300ma or so total current. The plate transformer isn't really all that large, same with the modulation transformer. I really don't see how this unit could ever power up and modulate a Viking 500. The Clegg unit was designed to modulate and power a 200w class input AM final.

Al VE3AJM


* DCP_0091.JPG (157.12 KB, 661x532 - viewed 246 times.)
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KO6YB
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« Reply #6 on: September 11, 2015, 05:51:37 PM »

I have a Zeus Rf and PS waiting for checkout/repair. What strikes me is that RF plate input power into the final is LESS than the tubes max dissipation. My photocopy of the (original) manual shows the final as a 4CX150A/7203. While you may think that the tubes max dissipation is 150w, wrong. It's 250 watts. Perhaps the design / prototyping was done with a 4X150, the production manual show 4X150A/7203. So it is running way conservative for the tubes it uses. My thoughts ran to why not run full power (per the tubes). But, it sure is going to last a lot longer running it at Clegg spec. Then, what about the HV & mod transformers? How conservatively are they rated? I have not investigated. Makes me wonder that driving a Viking 500 will really strain the Zeus PS.
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Pete, WA2CWA
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« Reply #7 on: September 11, 2015, 06:35:59 PM »

I have a Zeus Rf and PS waiting for checkout/repair. What strikes me is that RF plate input power into the final is LESS than the tubes max dissipation. My photocopy of the (original) manual shows the final as a 4CX150A/7203. While you may think that the tubes max dissipation is 150w, wrong. It's 250 watts. Perhaps the design / prototyping was done with a 4X150, the production manual show 4X150A/7203. So it is running way conservative for the tubes it uses. My thoughts ran to why not run full power (per the tubes). But, it sure is going to last a lot longer running it at Clegg spec. Then, what about the HV & mod transformers? How conservatively are they rated? I have not investigated. Makes me wonder that driving a Viking 500 will really strain the Zeus PS.

I don't recall Clegg using ceramic tubes in the Zeus.  The 4X150A was rated only 150W anode dissipation according to the Eimac spec: http://www.mif.pg.gda.pl/homepages/frank/sheets/088/4/4X150A.pdf

The 7203 is equivalent to a 4CX-250B not a 4X150A: http://www.mif.pg.gda.pl/homepages/frank/sheets/049/7/7203.pdf

The 4X150A is equivalent to the 7034: http://www.mif.pg.gda.pl/homepages/frank/sheets/049/7/7034.pdf
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Pete, WA2CWA - "A Cluttered Desk is a Sign of Genius"
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« Reply #8 on: September 11, 2015, 07:06:59 PM »

Hello Pete, yes I stand corrected. It was a typo. Double typo. Looking inside my Clegg Zeus RF deck, V6 is marked as 7034, not 7203. I did not mean 4CX150A. No C there. None the less, it is still 250 watt dissipation tube, running way under it's rating. Thanks for pointing that out Pete.
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« Reply #9 on: September 11, 2015, 09:08:12 PM »

Hello Pete, yes I stand corrected. It was a typo. Double typo. Looking inside my Clegg Zeus RF deck, V6 is marked as 7034, not 7203. I did not mean 4CX150A. No C there. None the less, it is still 250 watt dissipation tube, running way under it's rating. Thanks for pointing that out Pete.

The 4CX250B is a 250 watt dissipation tube. The 4X150A called out on the schematic is a 150 watt dissipation tube if we are to believe the Eimac specs:  http://www.mif.pg.gda.pl/homepages/frank/sheets/088/4/4X150A.pdf

Having two Clegg Zeus transmitters for roughly the last 20 plus years, you really don't want to push the rig past the recommended specs.
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« Reply #10 on: September 11, 2015, 11:53:44 PM »

Love the 4X150 and its kind. People don't want them so they are cheap. 

Eimac gives the lower plate voltage of 1250V along with the lower wattage for the 4X150 in that link dated 2-15-52.

Same in this Eimac manual http://69.36.164.11/tube/man/ei55.pdf with the page for that tube effective dated 5-10-54. - that previous link might be the same kind of page from this book.

This Eimac catalog from 1948 says 1000V for the 4X150A as Tenative data.
http://69.36.164.11/tube/man/ei48.pdf

Yet in this reference they state 250W for the 4X150A. (no date)
http://69.36.164.11/tube/man/eimpgt.pdf
as an aside, the plate modulated class C supply plate voltage rating is 1600V.

RCA says different, when they mention it in the TT-4. There may have been a mistake in a manual or an improvement in the tube along the way. RCA TT-4 (OCT 1962) gives the same voltage and power specifications for the 4X150A and the 4CX250B but a lower seal temp for the 150, it being glass may have to do with it.

4X150A
http://69.36.164.11/tubes/tt4/h0914.jpg
http://69.36.164.11/tubes/tt4/h0915.jpg

4CX250B
http://69.36.164.11/tubes/tt4/h0919.jpg
http://69.36.164.11/tubes/tt4/h10.jpg

There is also the STC Valve manual (SEP 63), which might be a unbiased third party?
It has a section on each and it also distinguishes between the 4X250 and 4CX250 types and the capacitances are different as might be expected (The hoi polloi say you can not just exchange one for another with no consequences).
Notably, the -150's plate voltage is 1250 above 150MHz, and 2000 below that.
http://69.36.164.11/tube/man/STCx.pdf

All the material gives 250mA as the maximum average current.

Not trying to stir up anything but rather bring information discrepancies to light. What looks consistent is that the older the data sheet, the lower the 4x150A ratings.

Maybe as manufacturing process for the 4X150A tube increased and people used more and more voltage on it, over the years they raised the ratings. It would be interesting to hear from someone who was working on this tube back in the day.
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VE3AJM
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« Reply #11 on: September 12, 2015, 10:19:56 AM »

I have a 1959 ARRL Handbook tube listing, and the RCA TT-5. Have a look at the 2 separate listings in the ARRL Handbook for the 4X150As, 1 entry for the straight 4X150A tube, and further down the same page another listing for 7034/4X150A. The first listing shows the tube as a 150w dissipation, and the second listing the 7034/4X150A as 250w, with higher plate voltages. Same forced air and all. I had never noticed that before. Never had any reason to either. The 7034 version has the 250w rating. Interesting stuff even though I don't have the RF deck as of now. Either tube should work FB in the Zeus.

According to the RCA transmitting tube manual TT-5, the 7034/4X150A is rated at 250w up to 150mc., but as per the TT-5, must be de-rated above the freq. range 150mc to 500mc., and de-rated in class C plate modulated service to 160w dissipation.

The 7034/4X150A is shown on my schematic for the Clegg Zeus.

Al VE3AJM
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Todd, KA1KAQ
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« Reply #12 on: September 12, 2015, 11:06:02 AM »

Beyond using it with something you already have Al, you might be shocked at what it could bring if you sold it. Seems a lot of Zeus RF decks have become orphaned from their PS/mod decks and even more seem to be missing the connecting cable. I've seen cables sell for $100+ which seems ridiculous since you can build one for much less. You just never know with the collector types who just 'gotta have one'.

Pete's words of advice about pushing the setup too hard should be heeded. I've seen several of these, including one set I gave away to a friend, with a bad LV transformer. Not sure if it's fair to call it a weak link without know how it was operated and what caused it to fail. Overall the Clegg gear is pretty stout stuff, well-thought out and well-built. And those Eddystone dials are like buttah!
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VE3AJM
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« Reply #13 on: September 12, 2015, 12:23:48 PM »

Hi Todd

Yeah I plan to use it (not sell it already) with a 200 watt class HF RF deck eventually, so I won't be pushing it. I had the unit given to me by a local long time 6m operator. He can't find the Clegg RF deck right now. My original questions about the unit were not answered but that's okay. There aren't that many of these out there and its not overly complicated to improve the audio quality. Tangential discussions can be somewhat useful.

It seems weird that Bama doesn't have even one Clegg manual on their site. I know there are other places online to find some of the manuals freely. Thanks Dan for sending your information.


Al VE3AJM
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