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Radio Frequency Tuned Amplifier RFTA (Amp., R.F.T.A Unit)

Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 829195) RF-Ampl. Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 829196) RF-Ampl.
Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 969145) RF-Ampl. Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 969147) RF-Ampl.
Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 969148) RF-Ampl. Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 969149) RF-Ampl.
Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 969150) RF-Ampl. Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 969151) RF-Ampl.
Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 1161818) RF-Ampl. Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 1168876) RF-Ampl.
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Radio Frequency Tuned Amplifier RFTA ; Crosley Radio Corp.; (ID = 829195) RF-Ampl.
Crosley Radio Corp.;: Radio Frequency Tuned Amplifier RFTA [RF-Ampl.] ID = 829195 933x848
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For model Radio Frequency Tuned Amplifier RFTA (Amp., R.F.T.A Unit), Crosley Radio Corp.; Cincinnati (OH):
RF amplifier
 
Country:  United States of America (USA)
Manufacturer / Brand:  Crosley Radio Corp.; Cincinnati (OH)
Year: 1922 Category: RF (Radio Frequency-) Amplifier
Valves / Tubes 1: UV201 or UV200
Main principle Radio Frequency Amplification only
Wave bands Broadcast only (MW).
Details
Power type and voltage Storage and/or dry batteries
Loudspeaker - - No sound reproduction output.
Power out
from Radiomuseum.org Model: Radio Frequency Tuned Amplifier RFTA - Crosley Radio Corp.;
Material Wooden case
Shape Tablemodel, Box - most often with Lid (NOT slant panel).
Dimensions (WHD) 7.5 x 6 x 5 inch / 191 x 152 x 127 mm
Notes Introduced in July of 1922 the Crosley RFTA was designed to add one stage of radio frequency amplification to the non-regenerative Harko Senior thereby increasing range and volume. The RFTA being tuned works efficiently over a band of wavelengths from 200 to almost 600 meters. When this unit is used in connection with the non-regenerative Harko Senior (in front), an amplifier tube is used in the Harko Senior Unit - with the grid leak and condenser bridged or short circuited. The detector tube is then placed in the radio frequency unit RFTA, thus this new unit contains the radio frequency tuner and the detector tube and its control. The reason for this trick is given here. Three different combinations were proposed by Crosley in 1922 for RFTA.
Here is a link to some sources for this model.
Price in first year of sale 15.00 $
Collectors' prices  
External source of data Ernst Erb
Source of data Radio Collector`s Guide 1921-1932
Literature/Schematics (3) July 1922 QST advertisement page 138
Literature/Schematics (4) -- Original prospect or advert (Data from original late 1922 catalog.)


All listed radios etc. from Crosley Radio Corp.; Cincinnati (OH)
Here you find 1439 models, 986 with images and 1022 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.



 


Forum contributions about this model
Crosley Radio Corp.;: Radio Frequency Tuned Amplifier RFTA
Threads: 1 | Posts: 3
Hits: 1398     Replies: 2
crosley: RFTA (Amp., R.F.T.A Unit); Radio Frequen
Konrad Birkner † 12.08.2014
17.Feb.12
  1

RFTA a mystery?

The RFTA is mainly intended to improve the humble sensitivity of HARKO Senior. But:

1) The HARKO Senior input is not ground connected, it is a series circuit of C and L. That means it is an open circuit for DC, which excludes its use as a plate load for a preamp. All the V/5 family is alike as far as I know.

2) ±A is routed through (marked P = positive? while N = negative) on RFTA but not on HARKO Senior. HARKO Senior's missing terminals at the left side mean that Harko is clearly a front end unit.

3) Another strangeness: why is the output of an RF amplifier marked "PHONES"?? and why did they add the audion capacitor of ca 300 pF?

In technical terms the name RFTA appears misleading.

Used as a preamp in combination with a simple receiver: how would the latter be hooked up? possibly to "Phones", but that sounds strange although it might work, provided the receiver input shows continuity for DC (which in those days was seldom the case, series tuning was preferred) to accept antennas with high capacity).

and why the P and N terminals at left hand?

As a phone booster the RFTA would hardly work, since its tuning circuit might not accept audio signals at the input, and 300 pF are not enough for audio signals.

Now marketing comes in: The name RFTA describes its overall function: to improve Harko Senior .Using the "real" technical name, it would not be understood why one should combine two TRF-Audions! The easy adaptation procedure was clearly explained.

How the combination RFTA + HARKO Senior works see here.

Ernst Erb
19.Feb.12
  2

Alan Larsen wrote to us and I think it is better put into here - for all interested readers in R.F.T.A.:


"Konrad is correct about the RFTA and it's placement after the Harko Senior. (See the schematic enclosed) The design of the RFTA apparently wasn't well thought out on Crosley or Israel's part and probably accounts for the scarcity of existing RFTA's. Here is a copy of the rather complicated Crosley directions for using the RFTA with the Harko Senior.

When this unit is used in connection with the non-regenerative Harko Senior, an amplifier tube is used in the Harko Senior Unit with the grid leak and condenser bridged or short circuited. The detector tube is then placed in the radio frequency unit, thus this new unit contains the radio frequency tuner and the detector tube and its control.

 
Not exactly plug and play for the user. The Senior becomes the Tuned RF and the RFTA is the detector. Too complicated for the average radio enthusiast."
 
First: On the other hand, one has to know that at that time most people buying a receiver were technically interested or even real radio amateurs.
 
You can compare that time with the years 1971 to 1981 when people first bought first CPUs. Intel 4004 from November 1971 was the first 4-bit central processing unit on one chip! The follower was 8008 and in 1974 the 8080. We can compare it with the crystal detector, the Fleming valve or the DeForest Audion. Then such use comes like an avalanche - first years it might be only a snowball ... With the integrated CPU the snowball grew only after the first integration as microprocessor, the Motorola 6502 (1975, incl. a PLA) and Zilog's Z80 (1976) ... and Intel 8080, which are not anymore mere CPUs but the entire microprocessor. with much more integration. Soon there were well known products like Apple, Commodore, Tandy (TRS80) but one had to be clever to add other things and many also made their own microprocessor. Same thing in an other time ...
 
Second: The reason for the RFTA was not to offer a new audion (they already offered also the "Crosley Detector Units" for that since February 1922) but to offer better reception with the Crosley non regenerative Audion, the Harko Senior.
 
It was not a misconception but a clever marketing move to avoid more Harko Seniors coming back. The combination with the 2-Step Amplifier was not the right answer when stations can't be heard because of sun activity. Either regeneration (question of rights) or an RF amplifier is then the only answer, also possible together with the Two-Step Amplifier. But Harko Senior was not designed for this and the trick with the RFTA was necessary.
 
RFTA was only needed for a very short time and is therefore hard to find for collectors. The model 6 (VI) (of Summer 1922) is this combination in the same box of a Harko Senior and the RFTA and the model X (10) shows the same but with the Two-Step Amplifier in one box.
 
By the way:
Also the "Crosley Detector Unit" was a marketing issue:
Instead of having to put the Harko Detektor (for 7 $) out of use when you felt you could afford an audion (Harko Senior for $ 16), you could just shorten your detector with a wire and use it as a tuner to put together with the "Crosley Detector Unit" (for 7 $), an audion without tuning - and you had the effect of a Harko Senior. You did not only save 9 $ but could go on using your crystal in case of a problem with the "Detector Unit". The complete set was still cheaper by 2 $ than the Harko Senior.
Ernst Erb
21.Feb.12
  3

When we consider the complication, hooking together radio modules or doing some change on a radio, we have to know how people lived at that time and what they did in their spare time. We also have to consider how simple radios were and easy to fix or change. An other fact is the cost versus having to work how many weeks or months. The fact that one could only either play music, go to music, have an expensive player piano ro mechanical music or a record player. Radio was the new thing and could also bring in news and other information.

Actual facts are that in 1922 ten times more radios and crystal detectors were homemade against sold instruments. In his book "Radio Manufacturers for the 1920's", Vol. 1, Alan Douglas has quoted "Radio Retailing", March 1928 with the following statistic:

Homemade sets:

1922 1,000,000
1923 1,500,000
1924 1,750,000
1925 1,000,000
1926   750,000
1927   300,000

Factory sets:

1922    100,000
1923    250,000
1924 1,500,000
1925 2,000,000
1926 1,750,000
1927 1,350,000

You can see that this changed as late as 1925.

 
Crosley Radio Corp.;: Radio Frequency Tuned Amplifier RFTA
End of forum contributions about this model

  
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