Viking II R13 / R30 Questions

[K9PNP]

If you have not done so, you might check the audio driver transformer that drives the 807 grids.   I am on my third one, although the second one was installed a few years back from the junk box and was fortunate to have lasted so long considering its condition when installed.

[WA1LBK]

Thanks for the info, Mitch, that's an interesting point regarding the AF driver transformer; I'll be sure to run continuity checks on it.  Haven't worked on the V II the last 2 nights due to a couple of long work days; was way too tired last night, & had to check out a problem on the older of our 2 vehicles tonight.  Hopefully will be able to get back into it this weekend.  Out of curiosity, in the event I do find a problem with mine, what did you use for a replacement transformer?   73,    Tom WA1LBK

[DMOD]

in the event I do find a problem with mine, what did you use for a replacement transformer?

I prefer the Hammond P124B Transformer.

http://www.hammondmfg.com/124.htm

Also, change R31 to 1.2k to reduce DC current through the transformer.

Phl - AC0OB

[WA1LBK]

OK, even though I was a little tired (after biking 18 miles yesterday & 34 miles today!  ), still had a chance to get back into it tonight.  Mitch, you called it precisely; first thing I did was run continuity checks on the audio driver transformer T3.  My Fluke 77 DVM showed the primary winding open.   Phil, I did look up the Hammond P214B transformer; got a bit ill when I looked up the price ($50 at Allied Electronics!).   - That's more than I paid for the Viking!  Might try digging deep in my (very substantial) junk box & see if I can find something that looks suitable (or another distributor that has the Hammond 124B at a more reasonable price).  Again, thanks for the help, guys.    Tom WA1LBK

[WQ9E]

Although the Hammond is a good transformer the original 1950s era transformers die from corrosion of the fine gauge wire and the modern equivalent to the Stancor A-53C works fine and is just over $15 from Antique Electronic supply:  http://www.tubesandmore.com/products/P-T156  It should readily outlast any of us.

I have used several of these as replacements over the years and all have held up well.  This same type transformer is found in numerous Heathkit and Johnson rigs so you might find one from a parts unit but the acidic paper used in the old transformer means even if it is good now there is still a good chance it will fail soon.  The little modulation transformers used in CE 10 and 20 series phasing rigs along with the telephone type relays used in CE rigs also fail due to this issue.

[WA1LBK]

Now $15.26 is a lot easier to stomach - that's pretty much in line with what I'd expect to pay.     I may still may look in my junk box, but frankly think that's a VERY long shot finding something suitable. Thanks for passing that along!    Tom WA1LBK

[K9PNP]

I agree with Roger.  That's the one I replaced it with the last time.

[WA1LBK]

Placed the order for the transformer with Antique Electronic Supply Sunday night; got an e-mail from them that it shipped yesterday.     Hopefully, replacing the open T3 should get the  V II up & running on AM; I may also temporarily hook a milliameter in series with the primary to ensure that the current through it is under 10 ma.  Also have to replace the 100 ohm resistors off the 807 grids, one is way out of tolerance at 150 ohms.  If things look good at that point, next step will be to remove the cabinet to wirebrush off the flaking, peeling original paint in preparation for a spray-can repaint.  Also been doing some work on the receiver I'm planning to use with the Viking II, a Collins R-388  , which was in pretty good working condition to start with; replaced the mildly fraying original AC line cord with a 3-wire one, installed new filter caps to kill a bit of AC hum, replaced the very worn-out SO-239 antenna jack with a new one.  Last night installed Treetop Circuit's SB-51 SSB product detector PCB in the R-388 for times when I want to listen to SSB on it.    Only other issue the R-388 has is very poor AM broadcast-band sensitivity, which looks like it might be a bad 6BE6, also on order from Antique Electronics with the transformer.  Now to try to find that coax antenna relay I think is lurking in the junkbox...   Tom WA1LBK 

[WA1LBK]

Got the new audio transformer in from Antique Electronic Supply a couple of days ago; also got in a 6BE6 & some #47 dial lights for for my Collins R-388 in the same order.  Took only a few minutes to install the 6BE6 & dial lights in the Collins (2 0f the 3 lights were out when I got it), & as I hoped it would, the 6BE6 replacement restored performance on the AM broadcast band equal to the HF bands, so that pretty much completed the work on the Collins.   Since the Collins was occupying the spot in the shack that I intend to place the Viking II in when I finish up with it, decided to move it into its "permanent"  location on the large computer desk that holds most of my equipment.  I wasn't about to trust the movable shelves on the computer desk with the R-388's 40 lb. or so weight,  so this meant a substantial "shuffling around" of the modern rigs (mostly ICOM gear; an IC-756 HF/6M, IC-275H 100W 2M multi-mode, & IC-475A 440 MHz. multi-mode).  The R-388 went directly on the desk itself; the IC-756 & Hy-Gain rotor control box on a shelf above it, the 2 VHF / UHF rigs up top.  Between relocating the shelves & recabling behind the desk, that kept me busy the last few evenings.
     With the frigid weather today, didn't feel much like doing anything outdoors today, so in addition to continuing the re-arrangement work in the shack, had a chance to finally get the new transformer installed in the V II; also changed R31 to 1.2 K per Phil's suggestion.  Temporarily connected my Fluke 77 DVM in series with the B+ lead of the transformer & fired up the Viking II; when I hit the plate switch, saw @ 4.5 ma or so through the transformer.     While it was still keyed, piped in audio from my iPhone 4's headphone jack into the V II's mic jack while running Faber Acoustical's "Signal Suite" audio generator app, monitoring the signal on a SONY ICF-2002 shortwave portable.  It's ALIVE!!! - Started off with the AF generator app set @ 500 HZ, swept it up & down a bit & heard the tone change appropriately in the Sony.  Also saw the modulator current change appropriately when I switched the AF generator app on or off.  Powered down the Viking, hit the B+ with a grounded test lead to make sure everything was discharged, & soldered the last transformer lead in.  Powered the V II back up & this time hooked up an old Shure controlled reluctance mic I had kicking around from long ago, I could now hear myself on the little Sony receiver.   
   Still a good amount of work to be done yet on the Viking; could hear some hum on the audio, know I have some re-capping to do, & still have those 100 ohm resistors on the 807 grids to replace (may check most if not all of the resistors & replace any that are out of tolerance).  Found not one but 2 antenna relays in the junk box; may also try to come up with a suitable relay to key the HV in the Johnson as well.  The meter glass in the V II is also loose  & occasionally jamming the pointer mechanically; have to fix that.  Also have to rig up a small dummy load with a suitable RF tap to use my ICOM IC-706MKIIG (set to QRP output) as a digital VFO.  Repainting the cabinet may have to wait for milder weather, not about to stink uo the house with spray paint (I'll do that outdoors).  But at this point, I have the satisfaction of knowing that the Viking II is going to work.   Thanks for the help, guys!    Tom WA1LBK
 

[Steve - K4HX]

Congrats! Hope to hear you on the air soon.

[K8ISS]

Hi Tom,

I have been following your post and I think I can shed some light on the clamp subject. I have a very early Viking II and purchased it from a friend some years ago with all the manuals. The very early Viking II's came without a clamp circuit and the clamp circuit came as a modification or separate kit. I have the modification instructions and diagrams for that modification if you are interested. I could scan and email them to you if you desire. My email is jrpatterson18@neo.rr.com

[N3GTE]

Little late to the party. I had a VII that didn't have a clamp tube original. A previous owner had mounted a small bracket under the chassis and add the 6AQ5. I just assumed that it was an early production.
You are better off losing the original driver trans the fq response stinks!
Terry
ps have my VII paired up with a 51J4

[K9PNP]

Glad you got it going.  Like I was taught years ago:  improvise, adapt, and overcome.  And, when all else fails do what we all do:  ask for assistance.

Just for the record:  The original manual I got with mine shows "revised 7/30/53" and shows the clamp tube [they call it a 'screen grid regulator'] in the written descriptions, schematic, and pictures.  Maybe mine was an early "B" model, if they had used that nomenclature for the VII.

[Pete, WA2CWA]

Glad you got it going.  Like I was taught years ago:  improvise, adapt, and overcome.  And, when all else fails do what we all do:  ask for assistance.

Just for the record:  The original manual I got with mine shows "revised 7/30/53" and shows the clamp tube [they call it a 'screen grid regulator'] in the written descriptions, schematic, and pictures.  Maybe mine was an early "B" model, if they had used that nomenclature for the VII.

There were no "B" models. Johnson just modified stuff as they went along in the production.