[patmat2350]

Color me confused. 
After looking at info here, I concluded that cabinet and chassis models were different things, but no?

My radio is an exact match to the 645K in the gallery here (my radio pictured below).

But the sticker inside says 655. And another sticker seems to say "10216A" which I saw was linked to the 645K model.

[patmat2350]

More: The part number of the "655" label is 39-4541. 1939???

[Ron Ramirez]

No,

39-4541 is the Philco part number for that label. It has nothing to do with years.

From the mid-30s through 1942 and to some extent after WWII, Philco parts were sorted with two-digit prefixes. In this case, part numbers beginning with 39- were chassis or cabinet labels.

As to which model - Ah! You have yet another of the end-of-the-model-year Phactory Phranken-Philcos, where the Philco factory stuck leftover chassis into cabinets of a different model to clear out inventory in preparation for the coming of the then-new 1937 model line.

Count the number of tubes in your radio. If it has eight tubes, it is a model 655. If it has seven (with two 42 tubes instead of three), it is a 645.

[GarySP]

No. That's the part number of the label itself. The 655 was a revised chassis. It's very possible they ran out of 645 chassis but still had cabinets. Just my guess ... others may have more details. The 645 was a 7 tube chassis, and the 655 chassis was 8 tubes. Quick count will verify what model you have. Take care and BE HEALTHY! Gary
Didn't look at the post above from Ron. Just repeated everything he just said!

[patmat2350]

A Phranken Philco!
Um, so it's special and super collectible you say?

[NostalgiaRadioTime]

I would classify it as being unique, but.....

and I think others here will bear me out....

not any more collectible or worth anything more than any other 1936-37 seven or 8 tube Philco console.

[Ron Ramirez]

I agree with Greg.

Edit: A Phactory Phranken-Philco is not more valuable than a regular Philco factory issue.

[GarySP]

It is a good example of how nothing went to waste. Many was the time that I would encounter model "change over" examples of cars when I worked years ago as a mechanic. Not uncommon, just as an example, that a 1971 would have a 1970 engine in it. Saw examples of that in all "Big Three" car companies. It didn't make them 'desirable', just more intense if the engines weren't identical. Take care and BE HEALTHY! Gary

[MrFixr55]

Had dealt with more than a few Franken-Fords in my life, especially my 70 Falcon wagon (302, AC, etc., sold it in '82 with 150K Mi on the original engine, saw it 5 years later, still running!) which was actually built in Aug 1969. Some parts were 69, some were 70. To make matters worse, when the Maverick was introduced in 1970, the Falcon was discontinued. What did they do with all the Falcon insignias? they stuck them on stripped down Torinos. I still love Fords though.

GM took a lot of heat for putting Chevy engines in Oldsmobiles (and the Chevy SB V8 was much better than the Olds SB V8). My wife's best friend had an '83 Chevy caprice wagon with an Olds engine.

Looking at the tube layout of that 655 with the RF amp, 6F6 (triode wired) driver and the 2 6F6 triode connected Push Pull output should be a great performer! However, I just reviewed the specs for the 6F6 in the 1937 RCA receiving tube manual, and I don't understand the advantage of triode- connecting the Push Pull 6F6s. The specs for Pentode P-P 6F6s for AB2 show 19 W at 5% THD, and 14W at 7% for triode connected P-P 6F6s. Shame that they did not have ultra-linear transformers and the Williamson circuit in the mid 1930s.

[patmat2350]

As a retired Ford engineer, I can tell you that few of those shenanigans would fly today. Too much tied up in certifications, plus just in time inventory control decreases chances of having excess stock to use

The radio (let's call it Phrank) does operate, but I don't know if Phrank operates well. Sitting in the middle of my stucco home, with no ground and just 10 feet of straight wire for an indoor antenna, I can get a couple AM stations with a lot of noise.

So I'll have to sort out the antenna situation before deciding if any parts are in need of renewal. And hoo-boy, is there a list of symptoms and possible fixes so I don't have to randomly change parts?

[radiorich]

Hello Pat,
That is does sound like the radio is working sum and I have found sometimes a ground makes it better or worse .
I have one wards Airline tabletop which when connecting earth ground to it the stations do not come in as strong .

Sincerely Richard

[RadioSvit]

MrFixr55
Ten years ago and until recently, I was actively involved in the design and creation of tube amplifiers and HiFi speaker systems, so I can share my experience. Here are some results of observations that I got thanks to measurements on a spectrum analyzer and in the process of listening. By the way, they are confirmed by the theory of high-quality sound reproduction.
The advantages of triode inclusion of 6F6 radio lamps over triode is that the spectrum of triode distortion is large at the 2nd harmonic, quite significant at the 3rd, but completely absent at the 4th, 5th and higher. In the pentode, the spectrum of harmonics is more uniform and much lower on the 2nd harmonic, but larger on the 3rd and extends up to the 10th, and therefore is generally much more noticeable and not more pleasant to the ear, because it causes discomfort. The higher the harmonic number, the more noticeable it is. That is, - the 5th harmonic with a value of 0.5% is much more noticeable to the ear than the 2nd harmonic with a value of 5%. The spectrum of harmonics of the amplifier in class A mode in triode switching is limited in number to the second and third harmonics, and does not extend to the tenth or more. At the same time, the second harmonic is hardly noticeable to our ears even up to a value of 10%. The third harmonic is on the contrary - its value is quite low and rarely exceeds 3%, but it is very noticeable and very uncomfortable for the human ear. And the presence in the signal spectrum of the fifth or seventh harmonic with a level of even 0.5% is a disaster for the ear and causes a sharp rejection. Therefore, even low-power single-cycle triode amplifiers in Class A are much sweeter and have a more correct sound, because their distortion spectrum ends with the 3rd harmonic, although at the same time they are very inefficient in terms of power compared to pentode amplifiers.
But pushpool has one feature - even harmonics of the 2nd order are mutually compensated, and odd (that is, 3rd, 5th, 7th) harmonics are added. So, - if we build Pushpool on triodes, we will get a very low value of distortion on the 2nd harmonic and a little higher on the 3rd and almost complete absence of distortion on all subsequent harmonics. We have such a phenomenal amplifier in Philco 37-116 deLux - it is difficult to find a console with a more pleasant, soft and accurate sound. And this is my favorite radio.
A completely different spectrum of distortions in push-pulls on 6F6 pentodes in pentode switching is a low level of even harmonics, but a much higher level of odd 3rd, 5th, 7th and up to the 11th. Because of this, such amplifiers sound more dynamic and sharp, very often unpleasant and quickly tire our ears. Everything described applies to amplifiers of class A, which were used in radio in the 30s...50s. When the radio and audio industry, in order to save money and increase power after the war, abandoned output triodes and began to use amplifiers of class AB or even B, to reduce distortions, they had to use Negative Feedback, which destroyed the naturalness of the sound, although the overall level of harmonics became lower than 2 %, but the range of harmonics extended up to the 12th...15th number. Therefore, their visibility grew.

I hope that this information will be useful to someone.

[MrFixr55]

Hi Peter,

That is an outstanding explanation!!!! I knew that RCA described 2nd order harmonic distortion as "pleasant", but never knew that the tolerance for higher orders of distortion were actually quantified and documented.

In looking at the 655 circuit, it appears to be a Class AB. The power and distortion specs that I quoted were from the 1937 RCA Receiving Tube Manual.

RCA (and others, I guess) tended to favor Class B Push Pull Audio for a while, But I have not heard one that I like. This includes the Crosley 02CA with twin 6AC5s driven by cathode follower 6J5s, an RCA 5BT (Type 19 Class B Push Pull driven by a correctly biased Type 30) and RCA 6BT (2 49s in Class B Push Pull driven by the same Type 30 Circuit as the 5BT. I find both of these to be harsh, especially when listening to classical music, even injected into the phono input, eliminating the distortion caused by radio itself.

I am a big fan of classical and sacred music but have no talent for performing it. Our local Roman Catholic parish has a lovely music ministry, a gifted music director, a 1200 pipe Chancel organ and a 4000 pipe Grand organ Either or both organs can be played from either console. We have choral concerts every spring with an orchestra, so I get to hear a good amount of live music. Our Chorus has a repertoire that spans from medieval to modern with a lot of Bach, Mozart, Palestrina, De La Victoria, Faure, Purcell, Mendelson, Rhineberger, etc. No matter how good the electronics, tube, transistor, OpAmp or digital, there is nothing compared to being there!

You and your country remain in my prayers.

Kind Regards,

John

John

[RadioSvit]

Thanks for your prayers and support for my country, John. I also want to add a short remark about the classification of tube amplifiers, which I made for my own use. In my opinion, two-stroke amplifiers with output triodes and triodes in a differential balanced input stage have the best sound. Of course, in class A. But such amplifiers are very expensive due to the high cost and costs of winding a multi-section absolutely symmetrical output transformer. Such amplifiers most accurately reproduce the sound and introduce the least distortion, and therefore are suitable for all genres of music, especially for symphonic classics.
I consider it the next in terms of accuracy and quality of sound reproduction
an amplifier with a single-cycle output stage on a triode and a driver stage according to the mu-repeater scheme. But such amplifiers are also very expensive due to the high cost and costs of winding the multi-section output transformer. Single-section output transformers from radio receivers are not suitable for such amplifiers. Such amplifiers are best suited for playing blues and jazz.
Even lower I would place the pushpool on the pentodes in the ultra-linear connection. This is already a much cheaper option, although it is very powerful. The amplifier on class A pentodes is even lower in quality, of course without negative feedback.
Well, then there are only push-pulls on pentodes in classes AB and B in various variations of the depth of Reverse Negative Feedback, from which there is little pleasure in listening.

PS. Oops. I caught myself thinking that my story about amplifiers has nothing to do with my colleague's topic about Philco ... If it interferes, I will ask the admins to move these three posts to a separate new thread, in which we can discuss the quality of low-frequency amplifiers of various radio receivers and sound reproduction systems .

[MrFixr55]

Hi PatMat,

IMHO, the best way to check out Phrank (Love the name) is to do the following:
-Remove and inspect the chassis. with an 65 year old radio, it is important that the electrolytic filter caps and all paper caps be replaced if this has not been done in the past 20 years (modern mylar or poly aps and good 'lytics were common 20 to 30 years ago. wax-paper caps will fail.

If the radio has a phono switch and input, use it to inject audio from a CD, MP3, etc., (Set the volume control on the radio and the device low and raise to best sound). This will verify if the Audio is good.

If the Audio is good, lengthen the antenna wire, find a pipe ground and turn off as many computers, CFLs, LEDs, TVs, etc. as possible to lower the noise level.

Operate a known good AM radio in the same area and compare performance. Note that more modern AM radios with ferrite antennas may pick up less noise.

Hope this helps.