Re: {Collins} R388 PTO



If the spread is contracted to the typical 980-990KHz, the compensator
won't have enough tuning range to stretch it back out.
I've done 3 r388 PTO's. The only thing I've ever done is the requisite peel one turn off of L2, and replace the matchstick caps. All 3 came back to within 2kc end to end when the cover is slid on. Let it run a half hour or so with the lid on, loosen the slug and dial it in.
I think we might be getting a bit carried away.
The tuning elements have had around 60 years to stabilize. Some of the exercises being discussed are based on meeting some arctic cold to condensing humid jungle heat mil-spec tolerance. The war's over. Your 388's likely never going to leave HVAC conditions.
Cheers,
Jim WA9Z

On 1/11/2012 7:24 AM, Curt wrote:
What is the purpose of the deep freeze treatment?

Thanks

Curt
KU8L
R-390A project
www.curtsworkshop.blogspot.com



On 1/10/2012 7:18 PM, Steve Darveniza wrote:
Hi Buck, it is best to remove the pto and overhaul it on the bench if
you can.
A screw driver will do a lot of damage to the locking collar on the
band spread inductor shaft.
You need to make a special two pronged tool to lock/unlock the collar.
idealy it is best to open the can ,clean out the old hard grease and
replace with fresh.There are some others who know of the best grease.
Do not touch the linearity " spine" until you have set the bandspread
as accurately as you can.
They will go to within 30 hertz quite nicely.
When you done this you will see most of the non linear problems have
evaporated.
The closer the bandspread the more linear right across the whole range.

If the PTO has not been used for a number of years it is best to leave
the PTO running for 2 to 3 weeks prior to any alignment.

Once you have aligned , wipe the O ring with rubber grease and use a
hair dryer to heat and dry out the can and the pto itself.
Whilst still hot ,screw the can on and place straight into the deep
freezer.
Leave in there for a few hours and all is done.


For fun ,you can do a linearity plot on graph paper at every 25 KHZ
prior to and then after wards.
Hope this helps
73 from Steve VK4VN
_______________________________________________
SHARE THE FUN: JOIN THE COLLINS COLLECTORS ASSOCIATION TODAY !
http://www.collinsradio.org/membership/

NETS: Tues& Thur: 3.805 MHz-2000 Central + Fri: 3.895 MHz-2000 Pacific
SUNDAYS: 14.263 MHz-2000 UTC + AM Net: 29.050 MHz-1200 Central
1st Wednesday AM Net 3.880 MHz-2000 local (ET, CT, MT, PT)

The Collins Reflector reserves the right to refuse access to anyone.

LIST HELP? ADMIN EMAIL: collins-owner@xxxxxxxxxxxxx
This ONLY goes to the list admins and does not post to the group!


_______________________________________________
SHARE THE FUN: JOIN THE COLLINS COLLECTORS ASSOCIATION TODAY !
http://www.collinsradio.org/membership/

NETS: Tues & Thur: 3.805 MHz-2000 Central + Fri: 3.895 MHz-2000 Pacific
SUNDAYS: 14.263 MHz-2000 UTC + AM Net: 29.050 MHz-1200 Central
1st Wednesday AM Net 3.880 MHz-2000 local (ET, CT, MT, PT)

The Collins Reflector reserves the right to refuse access to anyone.

LIST HELP? ADMIN EMAIL: collins-owner@xxxxxxxxxxxxx
This ONLY goes to the list admins and does not post to the group!





This archive was generated by a fusion of Pipermail (Mailman edition) and MHonArc.