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The response curve for the high band amplifiers shows gain at about 16dB from about 170MHz through to 230MHz making them perfect for 220MHz. It drops to about 10dB at 2 meters. Check the first page in this pdf. http://members.rennlist.org/warren/1kwHBfreqResponse.pdf Otherwise, the high...

Is this to be a disguise type antenna? Do you want it to remain looking like a flag pole? Would wires hanging in parallel along the side or raised radials be allowed?

Look at the components for date codes. Quite often ICs and transistors will have a manufacturing date included along with the part number. For instance, 8214 could mean 1982, week 14.

Or transmission lines entering the building and passing right by the AC entrance but not bonded. Wide copper straps going to the wrong places and in very long paths with many bends. Lots of money being spent, but done the wrong way. They always look and say it's been grounded and do not...

You'd actually be surprised by some of the dreadful installations. Tower grounded, building AC grounded, but no bonding between the two. The equipment acts a jumper between the two. It's surprising how long the gear lasts. If the system is designed and installed properly the added cost is...

Installed properly there is no need to disconnect the antenna during a storm. The feedline enters the house so the energy will be inside anyhow. With the RF side of things properly designed, installed, and bonded you could talk all the time during a lightning storm and there should be no...

If you're hoping to protect electronic equipment inside the building, you need to ensure proper bonding between the tower and AC grounds. The two grounds will often operate at different potentials, particularly during an electrical storm. Without a proper bond, any currents between the two...

It would be easier to leave grid bias on permanently. Plate and screen voltage can also be left on. Higher bias voltage will turn the tube off, or you could possibly lift the cathode return. No need to turn the power supplies on and off. There are several sockets available for the 4CX250...

The ones I'm referring to are like the channel 13 module presently there for $450. Item 271076939761 $1300 for the low band module is insane!

Has anyone tried the high band VHF Larcan modules? They should work nicely on the 220MHz band without any changes. Can they be modified for use on 2-meters? Are they worth scavenging for anything more than the MRF151 transistors? I see them on eBay and elsewhere, but not sure what they are...

It's hard to wreck the looks of a D104 mic. I've always considered them butt-ugly. Anything you could do could only improve it.

Phasing large antenna arrays with feedlines is quite common in broadcasting. Velocity factor is also important with quarter wave matching sections used in 4-element vertical dipoles. http://members.rennlist.org/warren/SplitterCableDesign.pdf

Bandwidth is dependant upon several factors such as conductor width and matching technique. More information is needed. An aluminum tower used as the antenna will have wider bandwidth than a very thin wire.

I didn't see any mention of thick conductors. Often antenna are made with a sort of cage to make them effectively very thick and increase the bandwidth. A six wire cage with 12 inch diameter makes a very wide band antenna. Even at 80 meters the entire band can be covered with less than 2:1...

The strip line sections are actually small transmission lines. They should not radiate. The only connections the makes are on the rear panel and through two clips holding it into the chassis. The sides slide along plastic channels. I'd like to take some actual measurements to find out for...

It's not my intent to gloat or brag, but what the heck. :) I can take other pictures to give ideas if it would help any. There is lots of other stuff in the cabinet that are useless. Controls to and from the TV exciter, filters, RF sample probes, etc are not much use any more. Band change...

Unloading wasn't as bad as expected. Pulled it out a bit, lowered to the ground, and then stood it up. The corner dollies really help with moving things around. The exciter was left behind. I didn't need the suspicion of putting the transmitter on air. The only failure the transmitter had...

I picked up a Larcan TV transmitter that uses a 6-transistor PA module for high band television. It's not the 6-meter version, but the modules can be fully swapped out. None of the filtering and metering circuits will be reused. From here all that is needed is a transmit/receive relay and a...

Maintaining equal phase in the cables is only part of the problem. You also need to maintain proper impedances throughout. Without proper length cables, the input impedance to the Tee connector will not be 50 ohms. You need to transform each 50 ohm input on the amplifiers to 100 ohms. To...

Cable impedance and length are both critical to make a phasing harness work properly. Perhaps the easiest 4-way splitter uses 50 ohm cable and three Tee connectors. One Tee feeds the other two with quarter wave lines. With two 50 ohm loads on the output Tee, its impedance becomes 25 ohms...