I have an Alpha 89, which is a manual tune version of the 87A. I also
have input SWR values that are less than perfect. My Alpha 99s are much
better, but then they have a 50 ohm resistor on the grid-driven input.
The input circuits of the 89, and I assume the 87A, are not adjustable
with a slug like the TL-922A or your 30L1, for example. Maybe one can
play with the spacing of the input torroids, but I doubt that is easy or
has much range. For basic operation I prefer my 99s over my 89, but
the 89 has better fault detection circuits, and is full QSK. So I live
with the input SWR and use the 89 as my CW amp. By the way, I run it in
SSB mode even on CW, as the keying waveform gets distorted when switched
to CW biasing.
73, Rob Sherwood, NC0B
JOS Earthlink wrote:
>Hi All,
>
>I just got an ETO Alpha 87a with Alphamax and it seems to work very nicely.
>I only see one problem with the amp - I'm almost certain that the RF input
>coils for many of the bands need to be adjusted. I noticed that the SWR
>out of the TS-950SD was running high into the 87a on a few bands. To be
>absolutely certain I placed my Powermaster powermeter between the TS-950SD
>and the 87a. I think the 87a RF input circuits are out of whack:
>
>At 28.0000 - 29.7000 Mhz SWR into the 87a is from 1.5 - 2.0
>At 21.0000 - 21.4500 Mhz SW goes from 2.3 - 1.8
>At 18.068 - 18.168 Mhz SWR goes from 1.7 - 1.4
>At 3.5000 - 4.000 Mhz SWR starts at 1.3 but goes 2.2 above 3.700 Mhz.
>
>I tried this with other tranceivers instead of the TS-950SD and all show the
>same. On my Collins 30L-1 it's a piece of cake to adjust the RF coil for
>each band by looking at Reflected power between the exciter and amp tuning
>the RF coil for minimal Reflected power but the 87a is a new beast for me
>plus I don't have any schematics. Any advice appreciated.
>
>Have a Happy and Healthy New year to All !
>
>73 Jerry
>K1JOS
>CCA #11906
>
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