[Amps] Ten-Tec Titan 425 - input SWR high

Colin Lamb k7fm at teleport.com
Sun Oct 19 09:21:03 EDT 2014


"Friends, for a long time now, the input SWR on my friend's Ten-Tec Titan
425 is very high (average > 2 on all bands) - when measured with a MFJ
analyzer at the input - with a 50R dummy-load at the AMP output."

The 425 has a trouble shooting chart, which has a number of possibilities.  This is a cathode driven amp with low-pass filter switched on each band.  So, if the swr is high on all bands, it is not likely the low-pass filter.

The first thing to check is the input coax.  Inside the amp, I would check the 3CX800A7 tubes.  If one tube is bad, the output impedance of the low-pass filter would change - which would affect the input.  If one tube is bad, you still may be able to get 1500 watts output, but the plate tuning would shift.  So, check your plate tuning numbers with the chsrt in the manual.  

73,  Colin  K7FM


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