[Amps] Tentec 425 RX problem

[Peter]

Hi

I face a problem with a TenTec Titan 425 amp.

I got this amp second hand and I have this problems since then
What happens:
The amp is hook up to a K2 and give 1500W out with 70 W input that ok!
Its setup to key via PTT (no full break in)
I got a delay for 1 second when switch back to RX.
But this happens only when the amp get power out and a TX for more then  
1 sec..
When there is no drive power (or very low ( 0,1W)) or when the TX is 
very short (1-2 dids in CW) there is no delay.

I have make a small video clip to see what I mean.
Its on www.xs4all.nl/~pc2a/tentec425.mp4
Its about 2Mb of size
(maybe you need Quicktime to see it)

I do RX/TX on a carrier.
First I transmit a few short dids and get RX immediately
Then a bit longer TX and see it takes 1 sec to get full RX
Then a few sort TX and all ok.
Then reduce power to 0,1W and a longer TX with a good RX

For this video the TX input was about 5W and get about 200W out.

I have already replace the vacuum output relais but still the same 
trouble during RX.
I have looked at the manual, but can't figure out how the input is switched.

Any advise?

Peter PC2A