What will become of us?

My wife asked me that the other day, this is what I told her:

Well... eventually we will die, and be buried (maybe). We'll lie in the ground for several hundreds or even thousands of years. A group of archaeologists will dig us up and make wild suppositions on our health, wealth and ancestry.

We will be cataloged and photographed, x-ray'd and DNA sequenced, then placed in storage, where occasionally graduate students will pull us out and make more outlandish conclusions about us. Eventually we will be discarded or lost, until one day billions of years in the future when the sun turns in to a red giant and envelopes the earth our molecules will circulate in the sun until we are blown off in to a planetary nebula.

Our molecules will wander through the galaxy until they are drawn in to the atmosphere of a planet in some other solar system, where biological life forms will ingest and excrete us, until we make it in to a higher life form that says "blorg... What will become of us?"
"WOW! you've really thought this through?" She said.
yes...yes, I have.


My First HD Radio

I have been looking in to getting an HD radio since I first heard found out about them a few months ago... yes I know they have been out longer than that, I just did not pay attention.

However it seems I missed the boat and all the inexpensive HD radios have been sold and there aren't many out there of decent quality and of reasonable price.

I was tipped off to an ebay auction for a Directed dmhd1000i hd radio for $25 bin "free" shipping. Not including shipping the unit cost me $11.

I just got it today. It was NIB and looks like it was never opened. It was also marked "Not for Resale".

This is not a standard table top radio. it is meant as an add on to a car stereo.

Here is what came in the box:
The radio unit.
Control panel with about 10 feet of cable.
a remote.
2 antenna adapters.
mounting brackets.
and a billion miles of wire to hook it in to power.

To test it I threw it on my bench and hooked it up to a 12 volt power supply. although it has an interesting way that it has to power up.

There are 3 wires Yellow, Red, and Black. You hookup the Yellow to a constant power source, the black to ground and the red to a power source that is switched.

To get it to power on I hooked it up with black to minus, yellow to positive, and then used an alligator clip to connect red to positive after the yellow was connected. If you do not do it this way the unit will not power up from the display.
Audio output is rather low but way more than strong enough for my homemade amplifier that has a 12ax7 input and single ended 35c5's for output. I have to turn the volume way down for comfortable listening. There are no specs on what it's audio output is.

There are 2 modes of audio out, one is through stereo RCA connectors and the other is through RF modulation through the antenna output to any frequency in the FM band. I have not tried the latter.

The unit is currently connected to a Discone antenna above my roof line.
FM analog sensitivity is excellent, I can pickup kcdx a 2700 watt xmitter 67 miles away (not HD) with a reasonably good signal. kvit a 10 watt station about 12 miles from me that is understandable (not HD).

FM HD reception is excellent for ALL stations in my area that have it. The unit takes about 7 seconds when tuned to an analog station to lock in the HD signal. Once locked in, the transition to HD is noticeable as the music quality improves, the noise floor almost disappears, and the volume drops slightly.

As for AM Analog sensitivity is excellent, kazg comes in great using either my discone or my 67' random wire antenna kazg is a 5000 watt daytime and 50 watt night time station. After sundown it still came in great and is 4 miles away from me. Most of my AM radios can barely get this station after dark.

There are only 3 AM HD radio stations in my area (that I could find). 2 are talk and 1 is a religious music station. 550 would not lock in after sundown even though it did earlier. The religious station locked in but sounded terrible. I think this is because of the recording quality of whatever they are transmitting since it sounded terrible in analog. The other talk radio station on 910 comes in very clear on HD or analog. Time to lock in seemed to vary for AM stations but was about 7 to 15 seconds. AM HD lock on was similar to FM with static and noise all but gone and sound quality improved.

On the underside of the daughter board with the large chip on it, there are several tiny LEDs that blink rapidly at a regular rate.

When I first powered the unit on the audio sounded not very good with what I would describe as clipping or static, but that has since disappeared, and all stations sound fine. I have not noticed any compression artifacts in any of the Digital streams. After about 2 hours use the unit is rather warm, about 115° or so.

My plan is to mount the DMHD-1000 either in a box or somewhere near my Silvertone 7407, with the control panel mounted somewhere that I can see it, and use the remote to control it.

I found that these suffer with a problem on the RCA connectors of over modulation.

There are 2 fixes for it, 1 I have confirmed works and the other I have not tried.

The first is to use the FM modulation mode, I have not tested this. The other which I can confirm works is to connect the ground tabs of the RCA connection to the metal case, and on to ground. This is the only problem I have found with my unit. Once I grounded the RCA shields the audio signal cleared up completely.


Admiral Y6071 9L2 Console

So a guy I used to work with approached me shortly after I started working at my job when he found out I worked on old radios, and he inquired about a console he owned that had been in his wife's family. He was looking to sell it and was wondering if it was worth the $100 he was hoping to get out of it. I explained all the vagaries of mid century consoles and how much they might be worth and why.
After several days I finally got him to get me pictures of it. It is a plane Jane el cheapo Admiral and after seeing it I told him if it worked it might be worth maybe $50.

Well step forward several months and his wife was tired of it taking up room in their house, so he approached me again asking if I wanted it I could have it for free. I told him I would give him $25. We picked it up and brought it home. I found out that it is not as big as I thought, It is long, but it is only about 3 feet high and maybe 2 feet deep. I am not sure where he got the idea that it was working as someone had cut all the wires to the speakers and the interlock. This happened a long time ago, because some of the wires had green goo leaking out of them. It looked like someone had tried to Jerry rig the console to play from an external source to the speakers.
 The Record player looked to be in good condition, and has a sharp needle in it.
I at first thought that If I did not get it working in the console, I could maybe mount the chassis in a home made box, and install an isolation transformer. When I downloaded the Sam's for it, I found that the output transformers are for a 1.4 ohm load. The tweeters and woofers are listed as 3-4 ohm in Sam's, in the picture it looks like the tweeters are in series and then in parallel with the woofer. So unless I wanted to use this Chassis with only the speakers from the console. I would probably need to replace the output transformers. Since this thing has stereo single ended 45b5's I doubt it puts out more than maybe 5 watts

The chassis was held in by only 3 screws, I blew off about 50 years of dust. I think it was made in 1964.
I tested all the tubes with me Eico 625, The only tube that is questionable was the 19EA8. Not sure if it is bad or my tester doesn't test it right, or what exactly. It measured Weak in both tests.

I checked over the circuit board and did not see any obvious defects. It took about 3 tries to identify the correct wires to input power (dim bulb testers are a life saver), as the wiring is cramped under chassis. I Identified the Proper speaker connections and hooked them up to my bench speakers.

I powered it up on AM and it worked, I scanned the AM band quickly and everything is good there. I switched over to FM and did the same thing (all good). FM Stereo on the other hand is muddled, and the stereo light does not come on (I have not checked if it is good). There was NO hum on any band. I changed out my Dim Bulb for an amp meter and got around .3 amps reading.

I rebuilt the power supply and replaced a cracked resistor circled in green on the right. I replaced several other capacitors on the main board.
I needed a replacement stereo indicator bulb GE 49. The problem is "Radio" shack does not carry them. There is a local place here called Lighting Unlimited, but my experience on old style bulbs is that they are more like "Lighting Limited".

The it struck me. This thing puts out 2 volts, 2 volts DC.... Hmmm, let me think. LED. AH HA!

I took the old bulb, broke the glass, de-soldered the bulb and melted out the epoxy or whatever holds the bulb in. I Soldered in it's place an old red LED I had. It works perfectly and unless there is some kind of power surge, will probably last forever.
 I also did a complete AM and FM alignment. Reception improved some, but stereo was still messed up. With some suggestion from a forum I fed a 19KHz signal directly to the input of the stereo decoder section, by doing that I was able to complete the Stereo alignment.

When I later got a Leader LSG 231 FM stereo signal generator, I was only able to improve the FM stereo alignment slightly better.

At some point I need to refurbish the Record player and then decide what to do with the cabinet.


Silvertone 7407 Refurbish

Picked up this Silvertone from an Antique store for $20 not working. The receiver chassis number is 528.54746 and the Amplifier is 528.69240 There is a number stamped on the amp chassis 30-125-2 or it might be 30-125-2a.
 It was plugged in and probably in use at one time at the antique store.

All it is, is a Silvertone Console Tuner, and amp Chassis inside a table top cabinet.
It appears to be all original inside.

It was in need of a recap.

This is the Schematic of my amp as found.

It has dual station dials, and indicator lights for being on station (in Mono),
 And in Stereo.

I had to replace:
1 - 6be6
1 - em84 with a NOS one from ebay.
2 - 6bq5
The resistor on the em84 eyetube.
all the electrolytics
several resistors on the right channel of the amp (the left all measured good).
There was 1 burned and split resistor in the tuner, and one singed resistor in the power supply.
I blew up a 100uf e-cap in the voltage doubler and had to replace that with a much higher voltage rated one. Seems that the amp originally had a 200vdc cap in the voltage doubler circuit. Why mine blew I do not know. The replacement 450vdc cap works fine. It has a Phono and Tape in. I have a CD player or mp3 player on the Tape In.
For $20+$45 in parts to fix, you can't get much better than that. It sounds really good through my Fisher XP-9C Speakers.


Recent Acquisitions

Eico 369 Sweep Generator

 Did a full recap and calibration

Lloyd's TM-838n 2 speaker radio.


 I installed an isolation transformer and a fuse.

Lambda LP-532-FM Calibrated DC power supply


Archer StereoDyne/3 Amplifier Clone

I was interested in building a small single ended amplifier, and found several that had been sold in the 60's. They went for quite a bit on ebay and I figured I would build one.

The amp in question was sold under several names and may have all used the same or similar design. The amps were sold under these names:
Archer StereoDyne/3
Truetest stereo/8
Monarch SA-10

I found this in an online copy of a Radio Shack Catalog.
I had found a stainless steel drawer at Goodwill. I had to order a couple of Edcor XSE15-8-2.5K audio output transformers, which took 6 weeks to ship. I had most of the other parts and only had to order some POT's and 3 meg resistors.

I designed the Layout of the amp in Autocad 2002. I then printed the drawings at 1:1 and taped them to the drawer.

 Center punched and drilled the holes.

Attached all the hardware, switches and pots.

 Then soldered in all the components.
There was some problems with hum and it took a couple of days to troubleshoot with help from an Antique Radio Forum.This is the original Schematic.
Here is the Final Schematic.
These are the pics of the finished amp. It still needs labels and better knobs.

Changes from the original design:
Added Isolation power Transformer to prevent accidental electrocution.
Better Audio output transformers.
Power indicator light.
3 prong plug grounded to chassis.
2 Channel input.
Fuses on input and output side of power transformer.
Used shielded cable for all the input wiring up to the 12ax7.
Added a 100uf Capacitor after first filter to reduce ripple by half.
Added a 22uf capacitor off of 125v source to pin 1 of both 35c5's to cancel out hum.
Removed "tone control".
Removed Stereo/Mono switch.

Hum is now down to 20 millivolts and can only be heard with your ears about 6 inches from the speakers.

This is a 1.5 watt per channel max, single ended tube amplifier. It will drive most any speakers just fine, frequency response is approximately 70 to 17000hz Not Hi-Fi, but 99% of the population can't tell. It will not do much in the way of deep bass, but bass is over-rated anyways.