Tuner question

[KG4URF]

I am running a Johnson Ranger 1 to a Yaesu YS-60 SWR/Pwr meter then to a B&W  VS300a tuner, everything works as it should. If move the cable from the Ranger and plug it into a Heathkit DX-60 I have no output or sidetone in my rcvr.  If I take the tuner out of the path, I have pwr out and a sidetone in my rcvr. Anyone know why the tuner works with the Ranger but not with the DX-60??

Doyle
KG4URF

[AC5UP]

The two transmitters should be interchangeable unless you're loading to an oddball impedance through the tuner. If you have a 50 Ohm dummy load, connect it directly to either transmitter and adjust the Pi network for best match. Do the same to the other transmitter. Connect the tuner and adjust it for best match without changing anything on the transmitter.

At this point you should be able to swap transmitters without any issues as they're both set to a common impedance.

If you can't get a match to the antenna without tweaking the transmitter that tells me you're compensating for an antenna system that's well outside the range of the tuner. Back in the day a Pi network usually had enough range to match a close-but-not-perfect antenna system without a tuner, and that was the preferred setup.........

( ? )

[WB6BYU]

Here's my guess:  try reversing the coax between the transmitter and the
SWR meter.


Now, to go about things in a more logical manner...

Where does your receiver get its sidetone?  From an RF sampler, or from the
transmitted signal?

Does the DX-60 load differently when the tuner is in the line and when it isn't?

Are you using the same plug to go into the rig in both cases?  I recently had a
similar problem where some coax plugs didn't work with a particular piece of
equipment.  The reason was that the outer edge of the inner contact had been
splayed out (likely by too much solder on the tip of a plug.)  As a result, the
center conductor made contact deeper in the plug than normal.  This worked
fine until I used a crimped PL-259, because the very tip of the center pin has
a smaller diameter where it is crimped, and this was in the part of the connector
where it normally would make contact.  I'm guessing that, in the process of
taking the tuner out of the circuit, you are somehow changing around the various
plugs in such a way that the one now going into the DX-60 now makes proper
contact.

Another option I've also encountered is that there is an intermittent connection in
the coax, and in the process of swapping cables, etc. you are wiggling or bending
one of the cables differently, and that is what is causing the difference:  this often
happens when the center conductor or shield is not properly soldered.

But because the symptoms make no sense otherwise, I'd look for a poor connection
somewhere, and the output jack of the DX-60 is a good place to start.

[KG4URF]

Thanks for the replies. The antenna is resonant about a 1.3 to 1 match. I have tuned up into a dummy load, makes no difference. I have swapped out different patch cords, doesn't make a difference. If I switch the tuner out (bypass) the DX60 works like it should. It seems like the tuner is absorbing the rf when it is in line. Guess I'll just switch the tuner out when I use the DX60.

Doyle

[AC5UP]

A tube final transmitter with a Pi output section can easily match a 1.3:1 SWR to perfection.

You don't need the tuner.

[KE3WD]

A tube final transmitter with a Pi output section can easily match a 1.3:1 SWR to perfection.

You don't need the tuner.

Absolutely so. 

Back in the day, before solid state rigs and even before having an SWR bridge in the shack, we used to merrily tune those tube rigs up on everything from bedspring to Beverage, not a problem. 

An antenna that has a 10:1 "mismatch" can still be an efficient antenna...


73

[G3RZP]

'5UP

I expected you to say 'because it's a Heathkit!'