[NJARC] field coil speaker replacement

[Bill Zukowski]

The problem is definitely the speaker.  I have a radio shack 6" that 
will fit, but I have to replace the field coil.  So far it looks like a 
resistor is not a viable alternative.

Tried manipulating the cone, and the voice coil scrapes no matter where 
I put pressure on the cone.  So it may not be a centering issue, but 
possible a burned/melted coil or perhaps the glue gave out and the 
windings have become detached.

My options seem to be:

-Use another speaker with the original or it's own transformer and 
replace the field coil with a choke

-Use another speaker with the original or it's own transformer and 
remove the field coil from the original speaker

-Re-build the original speaker

As this is a restoration job, I really have to speak to the owner to see 
how much he's willing to spend and how much he wants to maintain the 
integrity of the radio.  Unfortunately, I misplaced his contact info, so 
I have to wait for him to contact me.



Have the original speaker rerbuilt

On 4/19/2017 11:43 AM, Rich L. wrote:
> Bill, not a problem. Just trying to help.
> So just to clarify is the speaker bad or the transformer.  If it is the speaker most any 4 to 8 ohm speaker will work using the same transformer. If you haven't yet try using another speaker with the same transformer.
>
> Rich
>
> -----Original Message-----
> From: NJARC [mailto:njarc-bounces at mailman.qth.net] On Behalf Of Bill Zukowski
> Sent: Wednesday, April 19, 2017 10:56 AM
> To: NJARC at mailman.qth.net
> Subject: Re: [NJARC] field coil speaker replacement
>
> Just remember
> Reply = Poster
> Reply All = Everyone
>
> _________________________________________________________
> The field coil is 2125 ohms, and I used a 2900 ohm resistor.  Don't know
> the specs on the output transformer, but it matches a single ended 6F6
> to probably a 3.2 ohm speaker.  Another transformer/speaker combo sounds
> fine using the original field, but not so good using a resistor.
>
> Sorry for the confusion.
>
> On 4/19/2017 7:43 AM, Rich L. wrote:
>> Bill, is the speaker impedance 2100 ohms or is that the transformer impedance measured at the plug going into the radio?  I was successful in using the same matching transformer that is mounted on the old speaker and just changing the speaker with a 8 ohm speaker. Using a resistor will result in a power loss due to the mismatch in the impedance of the output tube and a 8 ohm speaker.
>>
>> Rich
>>
>> -----Original Message-----
>> From: NJARC [mailto:njarc-bounces at mailman.qth.net] On Behalf Of Bill Zukowski
>> Sent: Wednesday, April 19, 2017 2:18 AM
>> To: NJARC at mailman.qth.net
>> Subject: [NJARC] field coil speaker replacement
>>
>> Just remember
>> Reply = Poster
>> Reply All = Everyone
>>
>> _________________________________________________________
>>
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