Checking Antenna Resonance with a Grid Dip Meter

[KB3DKS]

Hello !
 Been awhile since my last post here and end even longer since on the air.
I am currently working up a dipole and have been using a later model solid state Millen GD meter along with a sensitive Frq counter to check out the resonance.
 If anyone has has used this method before please critique the following setup.
 First off I have a two turn link coil that slips over the plug in dip coil. This is directly
connected to a BNC connector to allow any type of interface. For the resonance testing I have placed a 50 ohm terminator in parallel with the coax cable to the untrimmed 140 ft dipole approx. 40+ ft above me strung around the insiide of the vacant fourth floor windows of this old mill building.
 The indicated dip frequencies appear to match the calculated dipole length, overlength right now, but I do not know if I am missing anything that could influence the response. Receiving is excellent and the Ant tuner also shows a slight overlength compensation but the receiver is rated for 75 ohms input. As yet I have nothing working of sufficient power to check transmitted SWR.
 So, does this testing technique appear to be usable? It worked out fine for my last station setup. The cost of a modern analyser is beyond me at this time.
 Thanks for any input!
Bill,
KB3DKS in 1 Land

[WA1GFZ]

Another thing you could try is put a 6 or 10 dB pad between the ant and RX and go into CW with a tight filter. The set the GDO up with a small antenna and TX into the RX. Tune the RX for strongest signal. The pad forces everything to 50 ohms. Don't worry anout the RX 75 ohm input of 50 ohms. There is a passive 50 ohm to 75 ohm pad made but you end up with around 5.7 dB of loss. This would be more loss than a slight missmatch at the RX.

[K1ZJH]

Should work fine for resonance, but it won't tell you the antenna's impedance.

Pete

[flintstone mop]

Frank, GFZ's approach will get you pretty close, where you won't be stressing any final amplifier components.

You mentioned that you have an antenna tuner. I think you are just about ready to start operating. It would be better to get the ant out of the barn.
Now you need a transmitter.
80 and 40M sounds like the bands for you.
160M would be better outside. Antennas need to breathe.
125 watts seem to be doing FB on 160M with the present conditions. Great propagation and quiet.

Maybe Santa needs to look you up on his list for an MFJ 259. That little box tells a pretty good story.

Fred

[WU2D]

Bill,

The GDO with the link should work fine to determine resonance as all have said. Is this antenna for receiving or is it for both receiving and transmitting?

If so, do you have a 20 dollar Lafayette SWR meter? - that will be the final authority on the match for a simple dipole.

Mike WU2D   

[KB3DKS]

Thanks for the input guys !!
 I will have to see how the impedance works out since the unusual antenna location inside a building with heating pipes and sprinkler systems having an effect as well as the ungrounded steel floor beams. It does hear real well !
 There is no option for an outside antenna within a reasonable coax run. Maybe in the summer I can find a way but... not my building.
  As far as Station gear goes, when living in PA had 2 Johnson VKIIs, Ten-Tec 238 Tuner, and a Halli SX110A or a 1970s Sylvania R1414/URR Mil receiver. An 80 and 40 mtr dipole common fed over the roof.
 Now due to a fire early last year have to go over about every piece of gear to remove the heavy smoke and water damage that really corroded the aluminum surfaces and rusted every single steel screw and washer.
  Hope to have a VKII back in operating condition before the first of the year and look forward to getting back on good old AM !!!!  I have bigger stuff too but that is another story.

 Thanks Again !!

 Bill, KB3DKS in 1 Land

[w3jn]

I have a Sylvania R-1414 also... has a crapped out power transformer.  You don't happen to have a manual for that bad boy, do you?