Silicon Detector Type 172 No 520 made by the Wireless Specialty Apparatus Co. For Sale

Silicon Detector

Wireless Specialty ApparatusCo. Boston Mass.

Type 172 No 520

This is as a very early and rare Silicon Detector made bythe Wireless Specialty Apparatus Co. of Boston, Mass.

It has stamped on the front plate; Wireless Specialty Apparatus Co. Type 172 No 520 Silicon Detector

And the following Patent dates;

Nov 20, 1906, May 19, 1908, Feb 16, 1909, Jan 21, 1908, Nov17 1908, June 15, 1909

Patent dates, I know, are not manufacture dates, but doplace it in the time frame of shortly after them. There is a very similar onelisted on the radiomuseum.org website that is Type IP 200. The difference I see from this one andthe IP 200 on the museum website is the blocks that hold the adjusting screwsfor the silicon have straight sides on the IP 200, and on this one I have the type 172, theyare flared out at the bottom and there are knurled set screws to lock theadjustments in place on this 172, that the IP 200 does not have. The IP 200 on the radio museum website is listed as showing in a catalog from 1919, I suspect this lower number type 172 isearlier, but do not know the exact date of manufacture.

I assume if you are offerding on this you already have an ideaof what it is and its rarity.

This example is complete and the micrometer screws workallowing free and easy adjustment of the antimony point on the silicon crystal.I have never put it in a circuit, but rather kept it as a collectible only, soit is untested in a circuit by me. The only cleaning I have done is a damp cloth and dusting it. It has some fine chips along the edges of the base and bakelite adjustment knob which you can see in the pictures.Otherwise it is in excellent condition considering its age.

I inherited it from a family friend who was an amateur radio operator and collector and worked at Bell Labs andI am sure knew its significance, which is why it was in his collection. AlthoughI do collect old radios it is time to let this go to a new home with a new collector.I am setting modest starting price of $199 since I believe it is worth much more.

Dimensions of the heavy Bakelite base are 5 3/8 x 3 7/8 x7/32 inch

Please look carefully at the pictures so you know exactly whatyou are offerding on.

Within the USA I am offering free shipping in a USPS Priority mail with insurance for the amount of the final selling price, also provided by me. However, the USPS only insures packages within the USA, so if you are not in the USA. It will be packedvery well.

If it ships outside of the USA I will be using \'s Global Shipping Program which states: The delivery address must be a residence or street address, not a P.O. Box, FPO or APO address. (Exception: P.O. Box addresses in Canada are fine.)

It will ship to the USA, Canada, and some parts of Europe only. So you won\'t be able to offer unless in those areas.

I only accept PayPal.

The Wireless Specialty Apparatus Company in Boston were a majormanufacturer of commercial and military radio equipment from 1907 untilsometime in the 1920\'s when it was absorbed into the RCA.
Founded: 1907
Production: 1907 - 1919
The Wireless Specialty Apparatus Company was formed in 1907 by Col. John Firth,Greenleaf Pickard, and Pickard\'s patent attorney, Philip Farnsworth.