Belcom LS120l radio (crystal filter)

[Sparkey55]

Re: Belcom LS120l radio (crystal filter)

Would that affect the crystal vibration frequency with additional mass?

That would depend on how much was used. I would think that any lose carbon particles would try to settle on the quartz blank and cause drift.

[eccerr0r]

Re: Belcom LS120l radio (crystal filter)

Do you have the old one removed or going to wait until you get the "new" one?

[llonen]

Re: Belcom LS120l radio (crystal filter)

I have had the defective one removed for inspection, most of the time it tests out fine on a scope and rf signal gen, its an intermittent problem and not one I am inclined to attempt dismantling of the unit as it is sealed with solder. For now its back in the radio, with regards to the one from ebay most if not all those old boards were single sided non plated through holes so am hoping its not been too mangled on removal. Will test before installation, along with several USA sellers for now this is the only one i have been able to find.

[stj]

Re: Belcom LS120l radio (crystal filter)

cut the top off with a dremel?

[llonen]

Re: Belcom LS120l radio (crystal filter)

Well the crystal lattice filter has arrived and the foot print seems to match the query defective filter so will probably not need to modify the PCB. I started re capping the PA stage and re making the solder joints, looking at the general state of the radio I will probably continue the process I also have some fer-rite beads on order.

Potentially bad capacitors notwithstanding the boards in the radio appear to be a mass of bad solder joints, well the through hole links / pins anyway so will probably end up as a full and much needed service. Will most likely need re aligning as well, I fully intend to leave the VCO block well alone as this is a known pain in the ass to setup and since it appears to work well I will not be touching it unless absolutely needed.

Will update as work progresses, I have a lot of customers work in though so this keeps getting pushed back as it is one of my radios lol.

[kc8adu]

Re: Belcom LS120l radio (crystal filter)

got a pic of the whole board?
if this is an old uniden board it is easy to hack it for 10m

[llonen]

Re: Belcom LS120l radio (crystal filter)

I can put up a pic of the whole board(s) of which there are several, the unit is not a Uniden chassis and includes quite a lot of discreet logic on one of the boards. It is however a very easy mod for 10 meters, one I carried out quite some years ago when the radio was obtained. I have had quite a lot of work come through and regrettably have yet to complete work on this set.

Rf board now recapped and fer-rite beads inserted where required, remounting the board is next, then carry on with recapping the main board(s).

pics as promised although not actually pics from my boards but you get the general idea of whats inside.