fellow radioheads,

i'm new to this forum and pretty new to tubes and circuitry in general. like many of you, i've had a great interest in audio for years and i want to preserve this beautiful technology to mostly hoarde for myself and sometimes share with people. this is the second all-tube radio i've bought with the intent to restore to a like-new state, while keeping original as possible. to be precise, it's an Admiral High Fidelity FM-AM Radio-Phonograph dubbed Model HiFi 6. the internal components are composed of a 1954 15HF1 FM-AM Tuner using fourteen tubes and including magic eye, a 4HF1 Amplifier using two 6SN7GT tubes and two 5881 tubes, and a 1HF1 Power Supply using a 5U4G rectifier tube. a total of 20 tubes in all.

first i would like to upload a few photos. second i plan on seeking your advice!

all the best,
zack

Welcome to the forum, that is quite a set you have there. If this is your first foray into anything mechanical/electrical, you may want to start off with something a little simpler.
Your basic tools, and a few meters, will be a good place to start. Give us somemore backround, so we can give better andvicew, in that direction.

Sams Photofact folder 258-2 covers this set - I'll see if I have a copy.

Wow!
One chassis radio
Another chassis amplifier with one heck of a transformer!
Yet another chassis for the power supply!

Yeah, that has gotta be one powerhouse! Looks like 5881 output tubes.

Any photos of the front?

-Steve

Great find!

The 15 tube AM/FM tuner/pre-amp with chrome plated chassis (black tag with tube layout diagram) looks like it may be sourced from Radio-Craftsmen. Maybe a Craftsmen RC-10 or “800” or variant? If so, it may be full of “Bumble-Bee” capacitors which will need to be replaced.

The amp and power supply also look suspiciously like Radio Craftsmen quality made units, but not any model number I know of (yet another Radio Craftsmen product to look for!)

Is that “Altec Green” paint on that 15” woofer?

Meade, I agree with you, the chrome chassis and terminals that look like the Craftsmen pieces I have. I'll bet there are a bunch of bumblebee caps in there that should be replaced. I don't know for sure, but the amp may have had KT66's as the original tubes and not 5881's that are installed now. I have 2 Craftsmen C550 amplifiers that use 6SN7's and KT66's for an honest 30 watts output. When restored the receiver should sound great. Harry

Amazing! Never knew Admiral marketed anything that high end. What a setup.

Edit: just realized, that gigantic hunk of iron on the amp chassis is the output transformer! Some power.

thank you guys for the comments and input thus far. i felt compelled to buy it when i saw it. the chances of it ending up refinished, let alone not being completely ruined must be very low, at least in this college town. i heard the woman who brought it to the store was trying to gut the innards so she could re-purpose the cabinet, and gave up very soon after only unfastening the speaker baffle from the front of the unit. she said it was too tough to continue further. also, a woman shopping in the thrift store wanted to buy it for a fish tank stand, which makes sense for obvious reasons. they were a bit rough with it on the way to the truck, i've rescued it. i've been wondering about its history- it's hard to get a reading of how many owners it's had, i could see it being one or many. either way, i can't wait to hear the smooth, quick response from that driver, which looks something like an ancient version of the Jensen P15.

dave- thank you, and i will see that the work is done right, one way or another. sam- thank you for searching for the photofact. steve- i will upload a photo of the front the next time i can. it's facing the wall in a room without good lighting. it has two mostly plain doors and the usual inside. the cabinet will definitely need attention but i used to refinish hardwood floors so i should be able to manage when the time comes and once i figure out the original materials. mag- from what i'm seeing online, this unit sure does look among the same bloodline as the Radio Craftsmen. i'll be looking more into that for sure. it's funny how tracing company history even 70 years ago can be an interesting quest. i can tell you that the 15HF1 chassis says "Chicago 47, Illinois" where Admiral was based. also, that driver has a hammertone finish which i can only guess is the result of atmosphere and time. i'll post a better photo asap. harry- the label below shows the 5881's as standard. i have a feeling a lot of these tubes are completely original, i guess we shall see. shout-outs to reece!

since i bought it over a month ago, i've been slowly and carefully cleaning each of the three main components, using alcohol and two entire rolls of papers towels. by no means am i new with things technical and mechanical but from this point on i'm going to need some help, and i would like to greatly thank you in advance. i'd really like to keep this process going in an organized manner, and hear the if's and why's of your comments. i understand there are more than a few ways to skin this thing and everyone has different preferences in replacement parts.

starting with the power supply makes the most sense to me. i know it's going to need new capacitors and i haven't been able to understand the specs of them thus far. i have basic tools, including a multimeter and soldering iron, of course. i figure this should do for now? soon i will post photos of the capacitors and the underside of the chassis and we can go from there.

zack

The cleaned chassis looks great and now I'm believing, you have Radio Craftsmen parts in an Admiral cabinet. From the date on the 5U4, the radio was built sometime in 1954. Parts replacement at least on the amp and power supply is not really difficult, the tuning section could be another story. If you are careful, the restoration of the tuner can be done with great results. Before starting on the chassis restoration, try to obtain the service info for the radio, it will make the job a bunch easier. Harry

harry- thank you for the advice. consider it done! i just bought the service manual for this Admiral HiFi 6 which should hopefully include more that just the 15HF1 Tuner section. either way i'm sure the 1HF1 Power Supply and 4HF1 Power Amp will be relatively easy to work on, the layout underneath each chassis is basic. you are also correct that the 15HF1 Tuner has plenty of bumble bee resistors but i'll take things in stride and get there after the power supply and power amp. shipping for the service manual is estimated between 5 and 6 business days. i'll upload photos of the power supply next. thanks to this forum i'm on a rollll.

zack

Pics of my HiFi 8 (I couldn't get the pics to post directly, here's the links). There was an earlier thread on this. It is a great sounding set!
http://antiqueradios.com/gallery/v/Admi ... 2.jpg.html
http://antiqueradios.com/gallery/v/Admi ... 4.jpg.html
http://antiqueradios.com/gallery/v/Admi ... 3.jpg.html
http://antiqueradios.com/gallery/v/Admi ... 1.jpg.html

SWEET!! Enjoy that rare Admiral!

Mine definitely has a mid 50's VM turntable with a ceramic cartridge. I had researched the original Admiral turntable and one of these days I need to procure one. The VM works well.

rene- i can tell you that my HiFi 6 has a similar tuner face but the Admiral unit has different styling and a darker finish than yours. it is very rich with a subtle cherry tint. i can't wait to refinish it!

i'm posting photos of the underside of the 1HF1 Power Supply and of the 3 filter capacitors on top that will need replacing. i want to stuff them so to keep the neat tubular tin towers.

zack

new to this forum, but have been working on tube amps for some time.

As a note, I would suggest placing diodes in series with your tube rectifier. This is not "Stock" but could save a lot of money in the future. two 1n4007 in series before the tube will protect your power transformer and your supply capacitors in case you develop a short over the tube. This is not a common failure but the fix is only $.45 of insurance against $100 transformer.
http://dynacotubeaudio.forumotion.com/t ... -diode-mod


I also fuse my heater leads as they do tend to short, ending the life a good transformer and likely your other tubes.

While all of this takes away from 100% stock restoration, if you plan on enjoying this for a life time, its worth the $1.50 in parts to ensure your not spending $100s on repairs. If you plan on selling it, that is a different matter.

Zack:

You asked about the blue and green devices in the [power supply. They are wire-wound power resistors, about 15 watts rating. Gotta be a little careful about reading the values: They are indelibly marked on the vitreous coating. For example, a resistor labeled 150 might have a value of 150 ohms, or the numbers may signify two significant digits and the decimal multiplier. In that case, the value would be 15 ohms. When in doubt, give it an ohmmeter check.

You don't have to re-stuff them unless you really want to. Most of us simply snip the wires going to the cans and install new caps under the chassis. That way the cans will remain and keep the original appearance.

It also save the rectifier tubes. I was blowing a rectifier tube about once every six months on my AVA U70. Did this mod, and haven't had a blow-up since. For all intents and purposes, it uses the tube only as a soft-start circuit, which avoid the issue of the hard turn on of the B+ on cold tubes that you would get if you just replaced the tube with diodes entirely.

Brett

sorry for the delay in response guys, i'm heavy into finishing up the semester. i wanted to let you know the photofact arrived the other day and i've taken some photos of the parts needed/possibly needed specifically for the 1HF1 Power Supply.

iccaros- thank you for the circuit diagram and explanation. thank you Brett_Buck for the further explanation. i will be looking into this immediately. i generally want to keep the unit stock but these old radios need new parts any way you look at it, and an update of circuitry in the name of safety and longevity sound good to me.

Alfred Corbin- thanks for the information regarding wire resistors! i will test them as soon as possible.

bobwilson1977- i've seen that a lot on this forum and that route sounds much better than restuffing. there are a number of other reasons i think leaving them under the chassis will be a good idea including being able to see exactly what work has been done in the future.

i'd really like to hear where you guys source your parts, and what you look for in replacement filter capacitors, specifically. i want to order them asap! below is a photo of the photofact and C-84, C-85, and C-86 are the three filter capacitors mounted on top of the 1HF1 chassis.

zack

Your radio should be fine without doing the diode mod to the power supply as the radio ran fine all these years like it is.

I do agree with installing a fuse in the heater supply, but looks like you have a fuse already on the primary side of the power transformer which should be enough to protect the transformer if the heater wiring shorts so long as the properly rated fuse is in the fuse holder.

You will need to replace all the paper capacitors (Mallory 150s are a good choice for replacements) and for the sake of reliability replace all resistors with metal film resistors except for the wirewound resistors which should be left alone.

Also clean all switches and controls with a good quality electronics contact cleaner such as Deoxit.

When you replace components make sure you do only ONE component at a time and if you have to disconnect more than one component at a time or you have to disconnect wiring be sure to take pictures of where the components and or wiring went.