[Radioroslyn]

Thank to the generosity of a Phorum member I was gifted a bunch dud wax/paper caps so I can make L76 look a bit more original. Unfortunity it uses a lot of .1mfd @400v like 15 or 16 of them. I'll try that other forum to see if I can turn up some more. Anyway I spent a hour or so removing the guts from the I have and cleaning them up. I think I ended up with 6 of the .1 I can use in the set along with some other values.

Terry

[Radioroslyn]

After asking around I ended up with with about half of the duds I need to recap. This thing is loaded with .1 @ 400v. So I decided to make my own duds. The problem is what to use for the cardboard tube? I can copy the graphics on a color copier but the tube is another issue.
So after ruminating on this one for a long while I came up with a solution. I found that the cardboard tube from a pants hanger is just about perfect. It's just slightly smaller in diamiter and long enough to make 10 caps. Will be off to the local copy shop to make some labels.
And now time for some pics! Seems like the pics never come out in the same order I put in. Anyway 1st two are of the HRO w/the fnt panel installed and the chassis cleaned up. The others are mostly for Mike and Sam's edification these are the shelf's I put up a few posts back to get some of the junk off the floor. When they where over they saw all the stuff on the floor. Notice I didn't take a pic of the floor. No comment.
Enjoy Guys!

Terry

                   

[sam]

wow terry looking goo now mike can walk around
and you have room now for some consoles
ps I have a manual coming for that rca radiomarine

[Paul Philco322]

We can send Fred Taylor over to really get you organized, he has got it going on. Really though I should talk. But sometimes just rearranging things makes you feel like you got something done.

Paul

[Radioroslyn]

Sean, So did you pickup that HRO on epay, the green one??

Sam, On your RCA I don't think it has an AC power supply so you'll need a good strong 6v or 12v battery (like car battery).

Paul, I've gotten to the place where I don't move much of anything unless I'm going to work on it or trip over!

So the L76 has been calling me by name since I moved it to the dining room table about 2 weeks ago. So I put on my bib overalls (this means I mean business). Grabbed my free SG-7 (Heathkit signal generator) that a friend gave me. and started at fixing L76. Well found why I got it for free, it makes rf but no modulation (400cy tone) which makes it a pain to use. After a half hour of looking up the info on it, replaced the filters and found a leaky paper cap that was the issue with the modulation. Now it's up and running properly!

Hooked up the power supply and powered up L76. As I posted before when I power it up seemed like the audio stages where working but the rest was unknown. Connected the generator to the second IF stage to see if it would pass a signal at the IF frequency (456KC). No dice! Then I checked the resistance of the IF transformer. Bummer secondary is open. Popped the cover off the transformer to investigate further. Both winding checked OK. Hmmm. Turns out I miscounted the pins on the detector tube socket where the secondary is connected. Cleaned it up a bit and back together it went.

But why won't pass a signal at 456KC?? Well I let that problem go for the time being and went to the 1st IF stage. Hooked the generator to the input (control grid) and then hook a signal tracer (it's an audio amp with a diode connected to the input so it can turn a RF signal to an audio signal) to grid of the second IF stage. I was rewarded with a weak signal from the tracer. So what do you do when you have a weak signal? You make it stronger, in this case by repeaking the transformer.

After that I went to the plate circuit of the mixer tube. This set has a crystal filter which is used to give this receiver very good selectivity it's connected to the plate of the mixer. Sets without a filter the mixer would feed the 1st IF transformer.  I wanted to see of it would pass a 456 KC signal. It did!

So what about the last IF not working but the transformer is OK? Well What I found was the adjusting condensers had oxidized so they where way out of tune (resonance). These IF transformers use small air variables not compression trimmers. The oxidization had formed at the rotor bushing. Out came the De-Oxit and a quick squirt into all the IF adjustments. Repeaked the IF stages and the last one peaked right up like it should (before it wouldn't peak at all). Funny thing they use the same tool to adjust as the Philcos a 1/4 hex nut.

Now it's picking up the generator thru the whole IF strip, detecting and making audio. The audio is distorted I'm thinking there's a bad mica cap in the detector stage.

More later! Stay tuned.
Terry
ps If any are interested a manual for the HRO senior can be found here:
http://bama.edebris.com/manuals/national/hro1935/

[Sean]

Great to hear you are breathing life into it. I didn't get that green/blue one in Arkansas. If I was definitely going to make a trip down there I would have made them a cash offer. They also had a Navy RAS version of the HRO Jr. I found a Hallicrafters SX-16 at a hamfest last weekend. Yet another boatanchor to put in the que.  

[Radioroslyn]

Hey Sean,
That's a nice set!!! I've had a few Hallicrafters sets over the years. I think I sill have a few of the AC/DC jobs S-41W and G, Echophone EC-1 and such. Did have a SX-25 and a SX-11. They are pretty hard to find in good cosmetic shape. They seem to rust pretty easily. As always enjoy replacing resistors and caps!

After the IF strip was working what the heck let's go for broke connected the signal generator to the ant post and see if the RF and mixer are working. Sure enough they where kinda. Had the chassis up on end to measure and connect the tracer and such. Lay it down flat and it would quit. Grrrrr. Turned out to be a loose tube the 1st RF amp tube.

So now it's picking stations but has some major issues. Audio is wicked distorted and low. Someone replaced the RF gain control but wired it backwards full is ccw and all the way down is cw. The volume doesn't work properly raises the tone a bit along with the volume.

At first I thought the distortion maybe an AVC problem so I measured the control grid voltage on all the RF/IF tubes. Looked ok. then I used the tracer and listen to the signal at each stage. Ahah!! All sounded nice and clean till I got to  the last IF amp. Grid was good. Plate was awful! Very distorted. Measured the cathode voltage and it was way high. Methinks the 300 ohm cathode has gone open. Soldered a replacement across the old one and now the plate signal is nice and clean too.

Onward to the volume issues. Still low and the distortion is better but not gone. Started thinking that the volume control was open. Flipped it back over and took the nut off of the control and there it was. The lead connecting the detector to the control was broken at the solder joint. The pot came off the chassis and took it apart to clean it.
Cleaned it up made a small splice for the broken connect and got it all back together.

Power it up and was rewarded with a mostly working set. Lots of volume distortion is gone. So now there are a few minor issues. Backwards RF gain control, crystal filter doesn't work( probably need the crystal cleaned) need the IF alignment again ( with the last IF amp working properly it needs to be dead on the crystal frequency) New cloth covered power cord and some cabinet stuff.

A very happy
Terry

[Radioroslyn]

The backwards RF gain control is bugging  me so out it came and install a nice new 10K linear taper Allen Bradly pot in its place. Now it works in the proper direction but all the gain is at the last 1/4 " of travel. The one that was in there did the same thing. GRRRRR. It's wired as a rheostat(just the wiper and one end are used) so I could just replace it with a smaller value and that would correct the problem. But that is tooo easy. I want to find out why it doesn't work with the stated value. I like headaches!! Maybe the original (that I don't have)has an odd taper that has very little resistance is at the far end. I will have to ask 7C and see what he sez!!!

Terry

[Radioroslyn]

Haven't shown yous guys any pic of 7C. It's kinda dirty and has some white paint overspray (I didn't) on the left side of the front panel. All in all it's in really good original shape. It's three years and one month newer that L76. Last pic is of L76 still working on the RF gain issues.

Terry
ps Pics NEVER come out in the order I put them in!!!

[Radioroslyn]

All the bits and pieces have arrived to make up the power cable. Have had the cable for a while now but needed the 4 pin plug and cover. Started at the 8 conductor cable wiring 2 sets of 3 wires for the heaters. I needed to use strippers as the cloth/plastic covering is tough can't do it with dikes I just end up cutting off some of the strands of wire. Got the plug end assembled now I need to scare up a grommet for  the chassis hole, don't have proper size.
Glued in the index marker. Front panel looks good! Also need to scare up a couple of 10mfd @ 25v or so for the two cathode bypass caps in the audio stages. Previous owner used 10@450v which is a little overkill and they are from '60's

Terry

[Mondial]

Hey Terry, I am working on your HRO's little brother. 

I picked this NC100XA up last year at a hamfest and am almost done with restoration. Here are a couple of before pictures.

National made some really nice equipment in the 1930's.

         

[Radioroslyn]

Hi Mike,
Would like to see some after pics...
I have it's father and son over here.
Have serviced both many years ago.
THe '200 I used to use on the air w/a VikingI.
Those where the days!!!! Back when I was 40 something.
Take good care.

Terry N3GTE

[Mondial]

Wow, that NC-200 looks in great shape. You have a nice National collection.

I don't have any final photos of the NC-100XA yet, but here are a few during restoration.

   

The chassis cleaned up nicely. I was able to find a matching electrolytic can to restuff to preserve the original appearance. The nice thing about this particular radio is that it was pretty much untouched, only a few electrolytics were patched in in the late 1960's. All the original paper caps were present and have been restuffed. A few of the resistors were open and replaced, the remaining ones were close to tolerance and left as is.


   



The catacomb movement was really stiff due to  shrinkage of the plastic bushings. I was able to split them lengthwise in place in the casting to relieve the tension and now it moves smoothly and freely

The big problem was the power transformer. These radios are known for their weak transformers and this was no exception. Secondary was shorted and it was was replaced with a Thordarson of similar specs. I made a mounting plate to match the existing chassis holes and fit the transformer within the original cover. You can see the new mounting plate in the original chassis cutout.





   

At this point after complete alignment, the radio plays great on all bands. I particularly like the dial and the wide freq coverage of each band.

[Radioroslyn]

Very nice work!!!
I'm kinda a hacker at this stuff. Most smart folk will pick a good candidate for restoration, very clean and very unmolested. Not me I always get the rusted dirty hulks than nobody wants. It's cheaper that way in the short term but you sure can kill alot of time making them look and work ok not great but ok. Like the RAS OMG!!

The NC-200 cabinet got a fresh paint job. It's was starting to show some discoloration from rust. I think that was back in '90 or 91. The bushing on both the 100X and 200 are metal. One of sets I don't remember which one the bushing would slide out of the catacomb frame. Really binds up the works. I remember reading that is plastic or teflon cap used to cover a coax connector that makes a nice replacement for the bushing. It needed a lot of resistors replaced I was surprised at how many had drifted. All the paper caps ect.

It too had a replacement power transformer. It's funny the bottom looks like the original with terminals and such but the top has a standard chassis mount bell on it not the one with a logo stamped in to it.

Terry N3GTE

[Radioroslyn]

A few new developments with the HRO . I finished up the loose ends, installed the power cord, replaced a few ecaps under the chassis, and removed extra parts I was using to troubleshoot. Buttoned up the bottom and installed the cabinet and going to called it done for now. It still has some minor issues like lettering on the knobs needs to be refilled just little stuff.
Anyway I took apart the D coil pack to clean it up a bit and found that a previous owner had written call sign in marker on the inside. So did some poking around and found that he is alive and well living Va. He's 77yrs old. Shot him an email to see if he remembers this set. Haven't hear back but just emailed him this evening.
Will get some pics together of L76.

Terry