>Hello to All,
>I'm seeking info on the Dentron MLA2500. I know the tubes are pricey, but
>what are some of the problems that have been encountered with this amp.
>Operating quirks, hardware problems etc.
1. 8875s are no longer in production.
2. Untuned input.
3. Too much lead length from the anodes to the Tune-C, resulting in a
Pandora's box of parasitic resonances within the 8875's "amplifier and
oscillator service" rated frequency range.
4. The glitch resistor is so small that, when the wolf comes to the
door, it disintegrates with a great roar.
5. The slow T-R relay is so slow it hot-switches with modern
The MLA-2500 is like unto a supermodel. It is compact, nice to look at,
but quite likely to be problematic.
- However, it was two, kaput 8875s which came from a MLA-2500 that
opened a door at Eimac in Feb., 1986 that allowed me to learn about
gold-sputtering in a followup telephone call and letter from Mr. W. B.
Foote, Eimac's specs engineer. (autopsy photos of this somewhat bizarre
phenomenon are in "Parasitics Revisited", Sept.-Oct., 1990, *QST* and in
Figure 24 on my Web site; info in 'Eimac Letter').
- Mr. Foote told me that Denny Had (Dentron) sent Eimac a prototype pf
the MLA-2500 for evaluation. Two Eimac engineers reportedly spotted
numerous design errors and wrote them up in an engineering investigation
report. Mr. Foote said that none of the recommended changes were made in
the production model. Nacherly, the MLA had a high warranty return rate.
When Dentron Co. went bankrupt, Eimac Co. was reportedly owed c. $150k
by Dennis Had. I guess you could say that Eimac got Had.
- R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.
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