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Gates FM 2H3
- Thread starter DaveR
- Start date
Could this be a Gates TE3 exciter?
The 2.5H is essentially identical to a 2.5K--they changed exciters from the TE-3 on the H to the MS/MX-15 exciter on the "K."
I have a PDF copy of the tuning procedure here at home. Mainly, re-tuning requires replacing L4, which is a 1/2" wide strap hanging on the PA grid (or 1" for frequencies below 98.1). To go from a higher frequency to a lower frequency you need to replace the existing strap with a longer strap. Unfortunately, they don't give you any information on the length of this strap at various frequencies.
In essence, you are designing a matching network to get the grid to 50 ohms at operating frequency. The re-tune also requires fiddling with the IPA. However, I wouldn't bother with the IPA if you can come up with an exciter that can deliver at least 30 watts. You can drive the final to full power directly from an exciter with around 25 watts. It helps to "T" a quarter-wave shorted stub into the feed from the exciter to the transmitter. Then just disconnect the B+ to the IPA.
I have a PDF copy of the tuning procedure here at home. Mainly, re-tuning requires replacing L4, which is a 1/2" wide strap hanging on the PA grid (or 1" for frequencies below 98.1). To go from a higher frequency to a lower frequency you need to replace the existing strap with a longer strap. Unfortunately, they don't give you any information on the length of this strap at various frequencies.
In essence, you are designing a matching network to get the grid to 50 ohms at operating frequency. The re-tune also requires fiddling with the IPA. However, I wouldn't bother with the IPA if you can come up with an exciter that can deliver at least 30 watts. You can drive the final to full power directly from an exciter with around 25 watts. It helps to "T" a quarter-wave shorted stub into the feed from the exciter to the transmitter. Then just disconnect the B+ to the IPA.
The 2 and 2.5 are almost the same. ..there is no real procedure in the manual. ... but you are not going very far... the tuning Block on the left side. Course tune. And the tuning arm on the right. ..should near level as u can get.... tuning Block left ... bottom 88mhz top 107mhz ... not sure how to tune h3 exciter. Mine was external. ... use bird from diver to final
.... turn ipa tuning until u get a match... on final I think if arm is going up higher in frequency. ... been so long I don't remember. ... note may have to take wire off of plate cap. 5 or so wramps of super 88 to insulation. ... driver something to work into... do not remember
..sorry. .. hope this helps
.... turn ipa tuning until u get a match... on final I think if arm is going up higher in frequency. ... been so long I don't remember. ... note may have to take wire off of plate cap. 5 or so wramps of super 88 to insulation. ... driver something to work into... do not remember
..sorry. .. hope this helps
Last time I retuned one of the H-series Gates boxes, I found using a grid dip oscillator was very helpful for checking my adjustments. If you can find one and the coil that will work on the broadcast FM band, you can dial the PA and IPA's right in. Or at least you can see if you are on the right track.
I'd see about getting a modern exciter as suggested and scrap that old one. Not only would you have the opportunity to get away from a tube IPA, but you won't have to deal with a rock-bound exciter and the audio quality will be so much better.
I'd see about getting a modern exciter as suggested and scrap that old one. Not only would you have the opportunity to get away from a tube IPA, but you won't have to deal with a rock-bound exciter and the audio quality will be so much better.
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