[BC] BE FM35A

[Milton R. Holladay Jr.]

No, not really: the new FM-35i I installed a year ago was the same basic
box, for IBOC.
I was thinking it was a 4CX 20000D, but, then,  it's been ~15 years. The one
I had had a grid tuning control and also had MVDS, which seldom worked
correctly; also had the works in a drawer: two drivers and an IPA.
Thanx for the history..........
M
----- Original Message -----
From: "John Lyles" <jtml at losalamos.com>


> As a former BE design engineer and FM TX design manager during those days,
I can speak for this.
>
> The BE FM30A was the original box with 8990/4CX20,000A tetrode, introduced
about 1981. [snip]
> later optional Z80 CPU, which became the MVDS option. This same controller
became the brain for the lower power rigs that I worked on, the FM1.5A,
3.5A, 5A, and later 10A and 20A models.
>
[snip] When we introduced the FM3.5A about 1983 at NAB, we made a new IPA
that was close to 88-108 without tuning, and used newer Thomson SD1460 or
TRW TP9383 bipolar parts. It was a single drawer for 150 watts, with
internal power supply. The FM30A then used this new design, combing two
drawers and driving with another, along with an improved input circuit that
was a lot more like the patented FM3.5A design, with all the impedance
transformation done on a microstrip board that had no tuning. This
eliminated the input loading control, and a source of narrowbanded input
response. >

> By the time the FM-35A was shipped, a different tube was used (4CX20,000C)
along with bigger plate transformer and so forth. The IPA was already the
new 'works in a drawer' system, and the controller was all state-of-the-art
at the time. There was no RTL nor crappy grid circuit and IPA in that model.
>
> Thanks for allowing me to set the story straight.  I would not hesititate
to take on an FM35A if the price was low, and if it was kept clean and dry.
However, that is getting to be an antique transmitter isn't it?
>
> John Lyles
>