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Crosley 1922: a problem year

Ernst Erb Jürgen Stichling Bernhard Nagel 
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Forum » Radio- and technical History » Technical history: 1920 and later » Crosley 1922: a problem year
Konrad Birkner † 12.08.2014
Konrad Birkner † 12.08.2014
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17.Feb.12 12:42

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In Summer 1922 the sunspots activity raised to a maximum. Radio reception was seriously affected. Receivers of low sensitivity like Crystal sets and Audions without reaction did not perform beyond local reception. Many customers returned their set for its humble performance.

Crosley did not have an Armstrong licence for reaction to overcome the sensitivity problem. Crosley went to RF-amplification. The main candidate to get improved was the HARKO Senior.

The HARKO Senior has a tuning capacitor in series. That excludes to hook it in the plate circuit of a tube (no DC continuity). A simple RF preamp was not applicable.

A very tricky way was chosen: The RFTA = Radio Frequency Tuned Amplifier was born.

The so called Radio Frequency Tuned Amplifier RFTA is in fact a TRF audion. To achieve amplification in combination with HARKO Senior it was named Amplifier, not to confuse customers. By swopping tubes and shorting a component the combination acted as a tuned audion with RF-stage. Improved sensitivity plus better selectivity by 2 tuned circuits!

How should that work? Crosley gave detailed instructions how to do.

1) the HARKO Senior is converted to an RF amplifier by shorting the Audion RC-combination, and the soft tube is replaced by a hard one.

2) the RFTA is linked after the HARKO Senior and its hard tube which was put into the HARKO Senior is replaced by the soft one (from HARKO Senior) since it is an Audion.

That means by swopping tubes and shorting one element the boxes swopped their functions!

The RFTA input is a floating coil in parallel tuning (that is the only real difference from HARKO Sen.), which is suitable for a plate circuit.

Notwithstanding its name the RFTA has a built-in Audion capacitor, and its output is named "PHONES". What else could it be but an Audion?

Rather tricky: had they sold it as an audion, then a soft tube would have been added. That is useless while such a tube is already in Harko. A hard tube was required to make the necessary swop. ("soft" tubes are good for Audion, but not for RF or AF amplification).

Fazit: The name RFTA is only valid for the combination with Harko (or similar Audion receiver w/o reaction). For the unit itself it is not correct !

A good marketing knack. Under "Audion" nobody would have bought. If I have an audion, why should I buy another one? And If I buy it as an audion: why a hard tube?

Soon Crosley managed to access an Armstrong license, which made such stopgaps like the RFTA obsolet.

This article was edited 17.Feb.12 16:37 by Konrad Birkner † 12.08.2014 .

Ernst Erb
Ernst Erb
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18.Feb.12 10:30

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The name Harko started with the first receiver Crosley offered in October 1921, then still as "Crosley Crystal Receiver", in November with a name change to "Harko Radio Receiver" - which was also offered in 1922 under this name.

February 1922, Crosley starts with ads for the first tube Crosley models: Among them is first the "Harko Senior Radio Receiver", sometimes called "Harko Sr." or Harko Senior Audion Receiver". But also the "Crosley Two Step Amplifier" and "Crosley Detector Unit" are introduced. The first such models were offered with overhanging lid cabinet and could be combined with matching cabinets. One combination offered is the "Complete Receiving Station". By the way: The wooden case with overhanging lid is the same for the "Harko Senior" as for the "Two Step Amplifier".

By September of 1922 the Crosley Harko Senior was being referred to in their advertising as the Harko Senior No. V. Shortly thereafter variations in the model were being offered at different prices. Options included Regenerative or Non-Regenerative, two different cabinets and engraved or stamped front panel.

Harko Radio Receivers
The different versions and how to date them

First we have to see about the first Crosley receiver, a crystal detector:
I state Alan Larsen: "I don't think there were probably any changes between the Oct. 1921 Crosley Crystal receiver and the Nov. 1921 Harko Radio Receiver other than the name change. Crosley apparently decided to do a marketing campaign around the Harko name after first designing the crystal set and then working on what would become the 1-tube Senior in Feb 1922. The second version of the Harko Radio Receiver crystal set was apparently never advertised as I have seen no ads. The first version Harko was last advertised in the April 1922 QST.Crosley ran no ads in the May or June 1922 QST. In the July 1922 QST advertisement, Crosley announced the new Crosley RFTA and also advertised the Harko Senior No. V and the Two-Step Amplifier. Interestingly this was the first mention and cut of the "refined" Harko Senior No. V showing the new Adam brown finish cabinet and the new style tapered knobs."

The versions of the crystal detector are (1) "Crosley Crystal Receiver", (2) same with name "Harko Radio Receiver" and (3) different versions of the "Crosley Crystal Receiver No. 1" with additional tuning knob and 4 binding posts on the right for connecting other sets. In this case we differed with 3 model pages.

Harko Senior

For really telling all the details, we need to have all advertisements and other papers - and we have to look into the sets. Since we have not all the facts together yet, I try to put together first the differences noted up to now. From what source I have, I bring the first date (month), but it can be earlier where we have gaps for advertisements etc.

Summary and Fazit:
Because of those many different versions for the same, we put all Harko Senior to ONE model page - with the exception of difference in the step switch. We link to this article.

Months we could cover with ads for 1922:

February:  Radio News page 725: Senior 3 step., Detector Unit, Two Step. Amp.

April: QST page 138 Detector Unit, Storage Battery; Radio News page 990.
May: (April-May Radio News page 990 with still overhanging lid, but var.cond. A,B,C).

July: QST page 135: Harko Senior V and 2 Step Amplifier. WLW Radio Apparatus.

August: Radio Broadcast (combination of 3, logo), Radio News page 215 = Harko Senior V

Radio News page 406: model RFTA, 5, 6, X, XV, XX.
Radio News page 407: 8 different combinations.

October: Radio News page ???, models V, VI, X. Sheltran transformer (but old Rheostat).


December: Crosley Catalog page 11 with V-A, V-B, V-C with regeneration (and without).

Two Step Amplifier with front switch - Combination with Harko Sr.
Letters and Models V-A, V-B, V-C new regenerative.


What are the differences we noticed already?


1 Lid:
Overhanging lid cabinet - later, the lid is integrated.
August 1922 lid integrated in "Radio Broadcasting".

2 Peep holes:
February 1922 without metal, jsut the hole. April both versions, later always with metal ring, called metal tube viewing grommet. In 1923 with a thicker ring, flat.

3 Step Switch:
Step Switch - from 3 to 7 steps.

4 Engraving on panel
no name (cheaper), Model name in one straight line "Crosley Harko Senior" (Feb. 1922, "Radio News" page 725), July 1922 in "QST" page 135 model name with logo (mod. V) with Logo - just Crosley - also in October 1922 "Radio News". But astonishingly in August 1922 in "Radio Broadcast" Crosley logo, second line "Harko Senior", also September "Radio News". Made by Tri-City has just Harko Senior in one line.

Most of the early Crosley Harko sets have a stamped front panel for the legends. There was also a later Harko Senior made that has an engraved front panel. This set has the Crosley logo with the lightning bolt through it (Icall it logo) and below it, it has Harko Senior engraved in the front panel. This is most likely the 1922 Harko Senior Model V-C. May 1923 Radio Broadcast ad show the 1923 Vc as much different.

5 Panel material
Crosley tells us in Radio News February 1922: "Complete tuner and audion detector assembled on a formica or other high grade dielectric panel ..." But when mentioned, you see "Formica".

6a Knobs small:
First knobs (tapered) with pointer (two different kind of), then with arrow.
The ad January 1923 in QST page 86 shows still with pointer - on page 83 also but with arrows on the panel! (VI-S, XII-S, VIII-S).
The ad in "Radio Broadcast Adviser" May 1923 shows arrows (also on front panel) for regenerative Vc and model X.

6b Main tuning knob:
On longer range one can also see the different main tuning knobs in size and form of the "handle".

Composed and photographed by Alan Larsen.

The ad January 1923 in QST page 86 shows number 2 on RFTA but on page 85 number 3 on Harko Senior V. I think that 1924 number 4 is already in use - by ad on May 1924 "Popular Science" (e.g. on model VI, 51 etc.). Alan Douglas (page 118) shows September 1923 for number 4 on a XJ model and 3B (Dave Crocker).

7 Cabinet:
Mahogany finish cabinet.
Adam brown mahogany cabinet.

8 Regeneration:
Non regenerative - regenerative.
Regenerating sets are also made with overhanging lid!


1 Rheostat:
Conventional, Crosley design. The ad January 1923 in QST page 86 shows the new design.

2 Variable condenser (tuning):
Different make of the compression condenser (book capacitor). For instance A, B, C.
February 1922 in "Radio News" page 725 already models A (wood frame and laminated wood), B (wood plates and die cast frame) and C (ground porcelain plates with die cast frame) available.
August 1922 in "Radio Broadcast" and "Radio News" page 215 offer for "B" type for $ 1.75.

3 Coil:
At least number of taps (branchers).

4 Socket
November 1921 "Radio News" page 441 - plain porcelain. Already February 1922 in Radio News page 725 it has about 4 "hollow throats" only the price is lowered in Summer to 50 cents, in 1923 it is 40 cents.  

5 Perhaps other changes
For instance in the "grid combination" of grid leak resistor and grid capacitor. Wiring etc.

This article was edited 21.Feb.12 15:07 by Ernst Erb .