[Hallicrafters] Speaker Matching Transformers for Sx-28AU

[Roy Morgan]

At 07:52 PM 6/13/2005, you wrote:
>Need help! I am rebuilding (along with other Hallis) an SX-28AU.
>This receiver has 5000 and 500 ohm speaker outputs. When it is done I will 
>be using a Jensen P-10R speaker for the PM 23 cabinet.
>Assuming that the speaker transformer in the radio is okay-what type of 
>transformer should I put on the speaker to match it to the output from the 
>receiver?
>I was told I could use a 70 volt matching transformer but I can't find any 
>info to back this up.

That's easy. I have a file that tells about the impedances found in a 70 
volt line matching transformer and will send it to Paul separately.. You 
can also find info on the web about this.  In particular, look up the specs 
on the Radio shack unit. I *think* this is it:


10W 70V Audio  (320-1031)     Specifications           Faxback Doc. # 9663
Transformer

Dimension measurements are within specification.

Primary Impedance (at 400 Hz 5V):

Secondary      Primary Watts
Loading           Range          No.1     No.2     No.3     No.4     No.5

   4 Ohm        10 W               535      535      540      547      525
                5 W               1025     1060     1040     1035      950
                2.5 W             2020     2000     2105     2010     1900
                1.25W             3905     4035     4050     4050     3850
                0.62              7120     7365     7205     7200     6855

   8 Ohm        10 W               570      595      585      590      595
                5 W               1110     1115     1150     1130     1135
                2.5 W             2050     2090     2245     2240     2240
                1.25W             4205     4100     4150     4305     4100
                0.62              7650     7400     7750     7605     7350

   16 Ohm       10W                555      565      565      555      550
                5 W               1070     1070     1090     1085     1020
                2.5 W             2105     2100     2200     2190     2050
                1.25 W            4070     4050     4100     4130     3960
                0.62 W            7405     7395     7400     7410     7150

Primary Inductance:              7.5 H    7.2 H    7.4 H    7.4 H    7.3 H
Primary Resistance:              198      201      202      197      200
Secondary DC Resistance (Ohm):   0.888    0.892    0.886    0.898    0.917

Insulation Resistance:.............................100 Meg Min. at 500 VDC
Hi-Pot Test:..........................................1000 VAC 60 Hz for 1
                                                   minute without breakdown
Impregnation:..........................................Varnish Impregnated
Frequency Response........................................100 Hz to 10 kHz

Specifications are typical; individual units might vary.  Specifications
are subject to change without notice.

(IR-04/12/95)

>If anyone has a manufacturer, part number and a distributor where I can 
>buy one it would be appreciated. A wiring diagram for this part would also 
>be appreciated.

Do you mean the 70 volt transformer or the speaker?

For info on the speaker you plan, see:
http://www.usspeaker.com/jensen%20p10R-1.htm
The thing apparently comes in three impedances, 4, 8 and 16 ohms.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
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