I'd like to get an older HT, an MT500 or maybe even an HT220, but the cost of having new crystals cut is daunting.
I can find used ham radio frequency crystals fairly easily and at reasonable prices, but I need to know whether these radios use a crystal at the working frequency or whether they use a lower fundamental and multiply to get the working frequency.
IE, to operate on 145.25 MHz, do I need a 145.25 MHz crystal or a 12.xxx MHz crystal?
Crystals for older radios?
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Re: Crystals for older radios?
okto wrote:I'd like to get an older HT, an MT500 or maybe even an HT220, but the cost of having new crystals cut is daunting.
I can find used ham radio frequency crystals fairly easily and at reasonable prices, but I need to know whether these radios use a crystal at the working frequency or whether they use a lower fundamental and multiply to get the working frequency.
IE, to operate on 145.25 MHz, do I need a 145.25 MHz crystal or a 12.xxx MHz crystal?
I haven't looked yet, but a good place to look is www.batlabs.com and the repeater builder site for information on your radio. You should be able to locate a service manual for that radio and it will answer your questions.
Re: Crystals for older radios?
One additional complication with the MT500 is that it uses channel elements so you would need to rebuild the channel elements with new crystals.
When you say the ham crystals are easily obtainable do you mean for normal ham units and not the HT220? Motorola commerical radios use different multiplications, IF frequencies and load capacitance from the typical ham unit. The crystal frequency is always multiplied, never at the working frequency.
When you say the ham crystals are easily obtainable do you mean for normal ham units and not the HT220? Motorola commerical radios use different multiplications, IF frequencies and load capacitance from the typical ham unit. The crystal frequency is always multiplied, never at the working frequency.
Re: Crystals for older radios?
Further to that, these radios require alignment at the specific frequencies desired. They are not plug-and-play. Depending on the radio you will also need specific jigs to connect the test equipment for the alignment, such as the HT220 antenna adapter box.