Possible to convert 42MC-50MC FM?

[sean]

Originally Posted by DavGoodlin

Does that mean these had both old and new FM bands?

It appears so. The first one should tune 88-108Mc on the 201-299 band and 42-50Mc on the 21-99 band (42.1 to 49.9Mc). The Stromberg Carlson radio would tune 88-108Mc on the 200-300 band and 42-50Mc on the 20-100 band (I would assume 42.0 to 51.0Mc).

BTW, the first photo is also a Stromberg Carlson:

http://www.radioatticarchives.com/radio.htm?radio=3198

[DavGoodlin]

Can anybody ID the chassis in attached photos?

The pretty one is a Stromberg Carlson 1210PL, also with both new and old bands....odd.

Dave 63

[sean]

See the link in my post above. The chassis is from a Stromberg Carlson model 1121.

[KentTeffeteller]

Some transitional post-WW II better sets had both FM bands. Zenith made quite a few old band-current FM band sets.

[DavGoodlin]

Thanks sean, I am getting loopy trying to use this site. Paging ahead helps.

I thought I was the only nut who would save an orphan chassis before I discovered it.

Dave 63
Now looking for FM48 with a 11-foot dipole..haha

[vintagecollect]

Someone HERE build this and try, I'm going to in nnext week or so. My brewster is just sitting collecting dust.

EASIEST converter, Only one crystal detector. If someone builds this, please state here specific values fo trimmer caps used.

link

http://books.google.ru/books?id=zt4D...nverter&f=true

[vintagecollect]

I built the convereter last day and it works like a charm, much more stable than TV tuner hack. Very stable with strong -- loud signal on 93.7 KJZY Station. Problem is, on picks up this one station only. Other stations just heard as modulation hum, any suggestios? Anyone familiar w/ prewar FM's , Please PM me! Will a signal booster work? I believe this to be strongest FM station, only tunes to this anyways? How many statios can anyone tunes w/ theirs using a conveter? Any tips?

Hello kent, I had a 1948? zenith console ol new band fm radio, Got rid of it. Should of kept it, needed reveneering, Zenith did ultra cheap photo veneer finish. Spin a record once in a while, had record player so was'nt teribly attached. Radio would of been worth saving if cabinet totally gone thru. Relized afterwards those radios not very common as early Fm.

[cbenham]

Originally Posted by vintagecollect

Someone HERE build this and try, I'm going to in nnext week or so. My brewster is just sitting collecting dust.

EASIEST converter, Only one crystal detector. If someone builds this, please state here specific values fo trimmer caps used.

link

http://books.google.ru/books?id=zt4D...nverter&f=true

Anybody figure out how to download page 233 with the convertor article on it? Doesn't seem possible to me.

In the meantime, you can buy a 'Sentry' HO 900 FM wireless headset system on eBay for ~$20 that transmits in the 42 to 50 MHZ band, crystal controlled and sounds good when playing a cd through it. It works great through my Philco 42-395 console.

Cliff

[Jeffhs]

Originally Posted by sean

It appears so. The first one should tune 88-108Mc on the 201-299 band and 42-50Mc on the 21-99 band (42.1 to 49.9Mc). The Stromberg Carlson radio would tune 88-108Mc on the 200-300 band and 42-50Mc on the 20-100 band (I would assume 42.0 to 51.0Mc).

BTW, the first photo is also a Stromberg Carlson:

http://www.radioatticarchives.com/radio.htm?radio=3198

Some older (late '40s) Zenith radios also tuned AM and both FM bands, although the old FM scale on these sets was actually calibrated in MHz (mc) rather than channel numbers on that range. The radios I'm thinking of are the old Zeniths with the arc-shaped tuning dials and the ones with round dials and a "Tone Register" tone control system. I am guessing the latter were made in the late '40s as well, owing to the presence of the old 40-MHz FM band which was eliminated from all Zenith, et al. FM radios after all FM broadcasting transitioned to 88-108 MHz by 1949 or thereabouts.

There may be next to nothing to hear on the old 42-50 Mc. band today, although I suppose one could overhear old cordless telephones which operated on the old 46-49 MHz range if such are still in existence nowadays, which I doubt -- all current cordless telephones now operate in the GHz [gigahertz] range. Most of the old 46-49MHz cordless phones have probably been scrapped, due to being forced into obsolescence by the new 5.8 GHz phones now in use.

[cbenham]

Originally Posted by Jeffhs

There may be next to nothing to hear on the old 42-50 Mc. band today, although I suppose one could overhear old cordless telephones which operated on the old 46-49 MHz range if such are still in existence nowadays, which I doubt -- all current cordless telephones now operate in the GHz [gigahertz] range. Most of the old 46-49MHz cordless phones have probably been scrapped, due to being forced into obsolescence by the new 5.8 GHz phones now in use.

You can buy "win" a 'Sentry' HO 900 FM wireless headset system on eBay for ~$20 that transmits in the 42 to 50 MHZ band, crystal controlled and sounds very good when playing a cd through it.

It works great through my Philco 42-395 console.

Cliff

[vintagecollect]

hello benham,

It is possible, I built this rather quickly using fine magnet wire on thin masking tape forms. Made quickly, works but is simple and somewhat fragile. here's a photo, second photo is of my android phone showing station being picked up w/ signal meter showing strong signal. Being a totally passive system, probaly only works w/ strong signals, works well when does.

I'm going to try and make different coils using thicker magnet wire, may work better since thicker? I'm going to get some fm boosters used for car and put on front end to boost weaker signals to compensate for passive system.

The trimmer caps I used are 9 to 180pf, wide range, these are surplus and I can get quickly if someone wants to try this along w/ 1N34 diode.

Please show us pics of your 42 please Benham!

[Reece]

Coils in the FM bands are usually self-supporting made from bare 12 gauge copper wire, wound on a pencil or some other form 3/8 or 1/2" diameter, and then slipped off. The wire can come from stripped scraps of house wiring. They can be adjusted in frequency by compressing or expanding the turns slightly. The heavy wire helps make them frequency stable.

[vintagecollect]

Hello Reece,

Sounds good to find some old house wire. It will need to be sprayed for insulation since both sets of coils are interwound onto each other. The diameter in projects states 7/8". The set benefits alignment with converter attached while adjusting trimmers also.

I tried converter on early post war Zenith I have w/ both old & new FM bands. Interestingly, the strong station came across as just strong modulation hum. I DID pick up a different station though, 104.9. station is very low and barely audible w/ volume turned all the way up. The Zenith was not aligned to be used w/ converter, just hooked tweak quicly up to see results. I really need to get those signal boosters to compensate for passive converter. Will post results later. I'm having a problem posting pics.

An ideal candidate for this converter may be a higher end large tube set, more sensitive ---should help in some way. The project states 12 wire used, I'm hoping someone here can build their version of converter w/ proper wire and post results since this is a simple tweak.

[Electronic M]

I don't see your pictures.

[sean]

Its was kind of convoluted to accomplish but here is the page from Google Books with the FM Converter in pdf.