[TenTec] K4DPK VFO drift stabilizer

[Don Rasmussen]

Hi Guys,

I installed the VFO stabilizer found at:

http://home.comcast.net/%7Ek4dpk/

in my Corsair II. It works with TenTec 580, 540,
Triton, Corsair, and Omni series.

This is a high quality board that has a look and feel
similar to the boards that are used in the Corsair II.
I mounted mine vertically along the case edge, just to
the right of the .25 filter position, using an
existing hole in the chassis. 

I have never been able to turn on the rig within 15
minutes of NET time and join the net without an
excessive amount of fiddling with the main tuning
knob. The stabilizer board fixed this.

Here are some drift comparisons with other
transceivers
for reference. Values are Hz from startup reference
frequency after 15 minutes, 30 minutes then 40
minutes. Receive only.

Drake R4C - 150/300/500
FT101EE   - 180/280/300
K2 (stock)- 110/150/170
Corsair II- 050/100/150
--- Dividing line here for acceptable ssb/cw ---
K2 w/TCXO - 30/40/No further drift after 30 minutes
C2 w/Stab - 30/50/No further drift after 30 minutes
OMNI 564 w/TCXO - Less than 20 cycles 
IC756Pro        - Less than 20 cycles 

The Corsair II with stabilizer also drifted an
additional amount (20-40 cycles approximate) when
transmitting for 5 minutes or more, then returned to
the original receive frequency after 5 or 10 minutes
of cool down time. 

I don't think this variance is from the PTO which is
controlled, it is most likely from other circuits in
the transceiver near the PA. 

This would most often not be noticeable using stock
ssb filters, but with the Inrad 2.8 filter and
receiving (example Orion transmitter on wide), you can
hear this small effect.

A note about TenTec PTO's. I had one that had a little
jump in it, 50hz every 3 minutes or so that was pretty
annoying on CW. Ten Tec worked very hard on this and
ended up fixing it after selecting parts by hand,
using trial and error for my repair. (This was on the
second trip to the factory, and they DID NOT charge me
at all for this work!) There can also be little
glitches with the PTO itself after the grease dries
up. I expect in both of these cases the stabilizer may
mask those effects. I connected the power to the
stabilizer to an RCA plug on the back of the Corsair
II. It's a great way to determine how the rig is
operating without the stabilizer helping it along.

That's the info from this qth, K4DPK (Phil) is also
very accessable and helpful. 

73,
de WB8YQJ/6 



		
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