Nice clean used band switch removed from DTR-2000L for sale:50.00 shipped
USA..Pse contact me off list:Jim,K7RDX...
----- Original Message -----
From: "jeremy-ca" <firstname.lastname@example.org>
To: "Gary Hinson" <Gary@isect.com>; <email@example.com>
Sent: Saturday, March 15, 2008 5:14 PM
Subject: Re: [Amps] Questions about Amps/Tubes/Design
> Here is what I sent to another ZL Gary.
> Replace the horrible nylon washers between the ceramic spacers and wafer
> with a RF grade plastic or Teflon.
> Build up the junction between the wafer and the spacer & insulators with Q
> Dope or melted polystyrene. You want the switch solder lug to have
> absolutely no path to the metal screw holding the sections together. All
> ones Ive had to repair or replace arc from the lug and thru the nylon.
> Super glue or epoxy an insulating spacer between the 160M padder lug and
> ground next to it.
> Complete new bandswitches are available thru Mouser for around $230 but
> Electroswitch wont supply just a single wafer.
> Its really not an "easy fix" as it takes time to remove and disassemble
> switch but even a partially eaten away wafer can be salvaged. You also
> the option of swapping sections.
> Note that the Dentron MLA-2500 uses the identical switch and the single
> wafer in the DTR-2000L is the same. Various 160-10M 7x series Alphas use a
> similar switch. Ive mentioned those in case some "dead" ones are available
> down there.
> Of course any amp with a blown switch can be gutted and rebuilt for 6M! I
> just finished an Alpha 76CA.
> ----- Original Message -----
> From: "Gary Hinson" <Gary@isect.com>
> To: <firstname.lastname@example.org>
> Sent: Saturday, March 15, 2008 7:59 PM
> Subject: Re: [Amps] Questions about Amps/Tubes/Design
>>> Amp Supply. The LK-500 had several models and every model had its own
>>> production changes. Weak link is the bandswitch configuration
>>> that allows it
>>> to arc to the support hardware. Easy fix if you do it before
>>> it happens.
>> I'd be interested to know more about that. More below.
>> My LK550 is still going but not quite perfectly. Maintenance/repairs so
>> have involved:
>> - New set of HV supply smoothing caps and load-sharing resistors, not
>> after I got it (about 1995?)
>> - 2 or 3 replacement Jennings vacuum output relays (I guess the QSK
>> doesn't stop mine hot-switching: I use semi-QSK now)
>> - At least 3 new power switches (no slow-start installed so the PD HT
>> transformer thuds at switch on - that's another "one day" project!)
>> - Popped a padder cap in the output tuning on 160m (changed 5 paralleled
>> 100pF HV RF ceramics, I think)
>> - New valves, one due to a heater short caused by heavy-handed removal
>> people, others to restore full output after a good decade of use
>> - Recently popped a bypass cap in the anode compartment (swapped a bunch
>> bypasses and couplers while I was in there - figured they are getting
>> The LK550 has 3 x 3-500s and would need about 150W of drive, I guess, for
>> full output. My little old TS850s can't get close, and to be honest I
>> like to thrash the gear so that plus the 500W license limit here ensures
>> get long life out of the valves :-)
>> Currently I'm having trouble tuning the amp on 80m (plate and tune
>> both max out - I've changed the padder caps for 80 but that didn't help,
>> now I suspect the bandswitch) and a weird problem on topband (output
>> at 100W and takes about 5 secs to 'warm up' - no idea what's happening
>> Any clues on solving the current problems would be much appreciated.
>> Gary ZL2iFB
>> Amps mailing list
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