[AMRadio] Johnson Valiant Audio Driver Xfmr - Wake Up Call


w0ng at comcast.net w0ng at comcast.net
Mon Oct 22 20:03:37 EDT 2007


Greg,

Thanks for the advice. I'll check out the AES website. I'm thinking you're referring to the Hammond 124D or 124E interstage driver xfmrs they sell.

My Valiant uses the 12AU7 driver tube just like your Ranger but mine feeds a pair of 6146's whereas your Ranger uses 1614's. I'm not enough of an expert at this to know if the impedance, etc. at the modulator grid is the same in both 6146 and 1614 modulators or not. Because of my lack of specific knowledge on this, choosing the correct replacement driver xfmr is a mystery to me for sure. 

The driver xfmr in my Valiant does have a center-tapped secondary, but from some info I found on the Peter Dahl website, they say the primary DC resistance is 230 ohms (12AU7 parallel driver plates) and the secondary DC resistance is 800 ohms C.T. (PP 6146 modulator grids).  I haven't yet found anything online that matches that particular spec. Guess I'll have to keep looking. Any other suggestions appreciated.

73
Bill
w0ng  

-------------- Original message -------------- 
From: "Greg" <bluebirdtele at embarqmail.com> 

> About a year ago I fixed a Ranger with one of the transformers from Antique 
> Electronics supply. I think what you're looking for is a common 3:1 or 4:1 
> interstage with a center tap. Right? 
> Go to the Tubes and More website and they should have them listed there. If 
> I'm not mistaken it's the transformer that is a reproduction of a big 
> American manufacturer's offering from way back when, The price was around 
> $20. If you can't find it, let me know and I'll take a look and see if I can 
> ID it for you and let you know. 
> 73's 
> Greg 
> WA7LYO 
> Kinston NC 
> ----- Original Message ----- 
> From: 
> To: 
> Sent: Monday, October 22, 2007 5:51 PM 
> Subject: [AMRadio] Johnson Valiant Audio Driver Xfmr - Wake Up Call 
> 
> 
> > In my quest for a replacement for the interstage audio driver transformer 
> > (T4) for my 1957 Valiant I transmitter I got a "wake up call" as to how 
> > expensive a new one from Peter Dahl can actually be. 
> > 
> > The quote was $189.66 plus $11.94 for freight and handling. Delivery is 
> > 4-6 weeks! 
> > I had no idea that a transformer weighing less than one pound could be 
> > that expensive. 
> > Certainly way out of my budget for sure. I love my Valiant but not THAT 
> > much, hi. 
> > 
> > I'm hoping that someone on this list has been in this situation before and 
> > has discovered a cost-effective replacement that they would be willing to 
> > share with me and the list membership. 
> > I'm getting kind of frustrated, I guess. Any help would be greatly 
> > appreciated. 
> > 
> > P.S.... I did contact Gary Brown, WZ1M, to see what he can do for me. Got 
> > my fingers crossed. 
> > Thanks, Bill, w0ng 
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