[Hallicrafters] My First Boat Anchor Restoration: SX101 MkIII

[bonddaleena at aol.com]

Hi Jason, been following this thread with great interest.
I started restoring boatanchors quite a while back. I have a URM-25D and a 26 (the vhf/uhf version). They worked fine for a few years. I eventually replaced the 25/26 combo on the boatanchor position with the 606A. I also was able to snag the entire line of 608 HP generators, several duplicates of some models. Even have a stack of the HP 7+ GHz gems. The size / weight of these are waaay too much to buy on e-Pay, er eBay, but I was able to get them cheap with no shipping charges.

On the URM-25D, you will probably find that the mica caps in the unit are cracked and leaking oil. Mine were. I replaced all the 'leaking' (both electrical and physically!!) caps and checked the tubes.

Don't agonize over the calibration. I have seen some very lengthy debates of folks trying to get the calibration of these old gems 'perfect'.
I couldn't care less, I ALWAYS use a frequency counter / attenuator on all my sig gens...... You can get a counter for pretty cheap. Plus they are easy to 'zero beat' against WWV.

Cap testing and replacement is another discussion that can pretty opinionated. ha ha

ron
N4UE



-----Original Message-----
From: Jason Hissong <jhissong at gmail.com>
To: rbethman <rbethman at comcast.net>
Cc: hallicrafters <hallicrafters at mailman.qth.net>
Sent: Wed, Nov 16, 2011 10:31 am
Subject: Re: [Hallicrafters] My First Boat Anchor Restoration: SX101 MkIII


I won the auction for the 25D on EBay.  I paid $116.00 for it.  I know
hat what I will be getting *may* not work and will need some
estoration.  I have several hams here locally that can assist me with
his with and  they have the appropriate gear to get it
alibrated/restored.  I also have a ham that is willing to loan me an
FR 1000S for my use (and as he said, maybe a deal I cannot refuse to
urchase it later).
This weekend, I plan on testing each of the tubes in the SX101 in the
ube tester (on loan to me).
Thanks for all the assistance and advice everyone.  I have learned a
reat deal just by talking with some of you on the list and directly
hrough email.  And thanks for the receiver info resources presented
n this thread.  I do understand how receivers work conceptually, but
ow it is time to dive deeper.
73,
ason N8XE
On 11/16/11, rbethman <rbethman at comcast.net> wrote:
 I agree with your assessment of the GR-1001A, and the good results with
 the AN/URM-25(X).

 I ended up with a HP-606B for the price of come and get it.  I also
 obtained an HP-312A from the same source and price.

 I only wish it WAS an HP-606A.

 I was given mt AN/URM-25 by a brother Warrior/Ham.

 I only had to replace one tube.  I've calibrated it against WWV and
 several crystal calibrators.

 I gave Jason one piece of advice regarding one that he was looking at on
 Ebay.  When you read the ENTIRE description, it reads the ubiquitous
 "As-Is" thing.

 That always makes me VERY nervous!

 They are however, very adequate for the job he's looking at.

 He has to decide how much use this test equipment will get used.  That
 has a BIG impact on how much someone wants to put in it.

 Carl, you and I probably use this stuff MORE than the masses.  This
 could be a one=time thing for Jason, OR very infrequent.

 His call!  (Along with whatever his Elmer's have available!)

 Bob - N0DGN



 On 11/16/2011 8:45 AM, Carl wrote:
> The URM-25D hung from one of my hands for about 3 years as a USN ET and it
> did an excellent job keeping our country safe.
>
> National had the GR 1001A's and they drifted so bad we used discrete
> crystal
> oscillators to do calibration. The only thing they were good for was IF
> and
> filter alignment along with general tracking and spot sensitivity tests.
> The
> coax adaptors can get pretty pricey also and signal leakage can be a
> problem
> when doing sensitivity measurements on the better receivers.
>
> With the NCX-3/NCX-5 and HRO-500 they were useless.
>
> The HP-606A replaced them and it is still one of the best generators even
> today. I have a pair of them and save the fragile 8640B for other work.
>
> Before getting the 606A's I rebuilt a URM-25D and used that for many
> years.
> They drift a bit but certainly not as bad as the GR.
>
> A good 25D will run $50-100 unrestored and around $40-75 for a 606A from
> what Ive seen at New England hamfests and several forums. Ebay is usually
> much higher.
>
> Carl
> KM1H
>
>
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